A FEASIBILITY STUDY OF THE INSTALLATION OF A ROOF MOUNTED MICRO WIND TURBINE

AT THE NORFOLK AND NORWICH UNIVERSITY HOSPITAL

by

Haqiki Aplesiasfika

Thesis presented in part-fulfilment of the degree of Master of Science in accordance with the

regulations of the University of East Anglia

School of Environmental Sciences

University of East Anglia

University Plain

Norwich

NR4 7TJ August 2009

© 2009 Haqiki Aplesiasfika

This copy of the dissertation has been supplied on condition that anyone who consults it is

understood to recognise that its copyright rests with the author and that no quotation from

the dissertation, nor any information derived therefrom, may be published without the

author’s prior consent. Moreover, it is supplied on the understanding that it represents an

internal University document and that neither the University nor the author are responsible

for the factual or interpretative correctness of the dissertation.

i

ABSTRACT

The Norfolk and Norwich University Hospital (NNUH) is the main centre of health services in

Norfolk County, which is run under management of the National Health Service (NHS). The

NHS has set a 10% carbon reduction target to be met by 2015 (NHS, 2009), as part of the

strategy to meet the UK Government’s Climate Change Act. One of the solutions to achieve

the target is by starting to alter the current fossil fuels energy sources into low carbon forms,

such as renewable energy. A roof mounted micro wind turbine installation has been

proposed by Serco, which acts as non-medical services provider for the NNUH, as an

alternative clean renewable energy source to supply electricity in a specific area in the

NNUH. This research presents a feasibility study of the installation of a roof mounted micro

wind turbine at the NNUH. The study mainly used the Wind Yield Estimation Tool, which has

been developed by Carbon Trust and Met Office, to estimate the wind speed at the NNUH

site, and the technical and economic performance of the most suitable turbine. The results

obtained show that the installation of a roof mounted micro wind turbine is technically

feasible, shown by the ability to generate power that can supply nearly 50% of the electricity

demand of a main cafe in the NNUH. By replacing 50% of the current electricity source from

main grid, consequently, the carbon emissions attached to fossil fuels consumptions will be

reduced as well. Furthermore, the economic analysis showed that the turbine installation is

economically feasible, as the payback periods can be achieved within approximately 9 years

with the forthcoming Feed-In Tariffs scheme in April 2010.

Key words: Micro wind turbine, Carbon emissions, Renewable energy.

viii + 69 pp.; figures; appendixes; tables.

References : 81 (1992-2009)

ii

ACKNOWLEDGMENTS

Firstly, I would like to thank Allah SWT for giving me the chance to pursue an M.Sc degree in

the United Kingdom. I am also very grateful to my beloved parents and family who always

support and trust me in chasing my dream to study abroad. For you I always work hard and

for you I give my best endeavour. My sincere gratitude for Dr. Dick Cobb as my study advisor

and supervisor, who has never stopped giving me help, attention, support, valuable insights

throughout the year of the course. Further thanks go to Chris Paul, Philip Willgress and

Prabin Ranjitkar who had given me information about the Norfolk and Norwich University

Hospital (NNUH) and all the good inputs about renewable energy. More gratitude to Dr.

Stephen Dorling and Turki Habeebullah for helping me understanding the wind stream and

obtaining the wind datasets. Moreover, thank you to Dr. David Benson and Dr. Alan Bond for

all the guidance and support in studying EAM. Lastly, many thanks to Fathan, Silvi, and all of

my friends for always being there for me in good times and bad times. I would be nothing

without all of you. Once again, thank you everyone.

iii

CONTENTS

ABSTRACT ................................................................................................................................. i

ACKNOWLEDGEMENTS ............................................................................................................ ii

CONTENTS ................................................................................................................................ iii

LIST OF FIGURES ....................................................................................................................... v

LIST OF TABLES ......................................................................................................................... vi

LIST OF APPENDICES ................................................................................................................. vii

LIST OF ABBREVIATIONS ........................................................................................................... viii

CHAPTER I. INTRODUCTION ................................................................................................... 1

1.1. Background ...................................................................................................... 1

1.2. Outline .............................................................................................................. 2

CHAPTER II. LITERATURE REVIEW .......................................................................................... 3

2.1. Climate Change and the Need for Renewable Energy ..................................... 3

2.2. Renewable Energy ............................................................................................ 6

2.3. Renewable Energy Schemes in the UK ............................................................. 7

2.4. Small Scale Wind Energy .................................................................................. 10

2.4.1. Issues related to Small Scale Wind Energy ........................................... 12

2.4.1.1. Wind Power and Turbine’s Performance ............................... 12

2.4.1.2. Environmental Impacts and Planning Permission .................. 14

2.5. Norfolk and Norwich University Hospital ......................................................... 15

2.6. Objective and Aims........................................................................................... 18

CHAPTER III. RESEARCH METHODS ........................................................................................ 19

3.1. Methodology................................................................................................... 19

3.1.1. Assessment of the Proposed Turbine Site (the NNUH) ........................ 19

3.1.2. Identification of Suitable Micro Wind Turbines ................................... 22

3.1.3. Assessment of the Turbine’s Performance .......................................... 23

3.1.3.1. Estimation of Annual Energy Output and Carbon Saving ....... 24

3.1.3.2. Cost Benefit Analysis and Estimation of Payback Period ....... 26

3.1.3.3. Sensitivity Analysis .................................................................. 27

3.2. Limitations ........................................................................................................ 28

iv

CHAPTER IV. RESULTS AND DISCUSSION ............................................................................... 29

4.1. Assessment of the NNUH Site .......................................................................... 29

4.1.1. Site Profile ............................................................................................ 29

4.1.2. Roof Mounted Turbine Siting Location ................................................ 30

4.1.3. Site Wind Conditions ............................................................................ 31

4.2. Identification of Suitable Turbines ................................................................... 36

4.3. Assessment of the Turbine’s Performance ...................................................... 39

4.3.1. Estimation of Annual Energy Output and Carbon Saving .................... 39

4.3.2. Cost Benefit Analysis and Estimation of Payback Period ..................... 41

4.3.3. Sensitivity Analysis ............................................................................... 44

4.3.3.1. Varied Wind Speeds .............................................................. 44

4.3.3.2. Varied Electricity Tariff .......................................................... 47

4.4. Summary .......................................................................................................... 49

CHAPTER V. CONCLUSIONS AND RECOMMENDATIONS ..................................................... 50

5.1. Conclusions ....................................................................................................... 50

5.2. Recommendations ........................................................................................... 52

REFERENCES ............................................................................................................................. 53

APPENDIXES .............................................................................................................................. 60

v

LIST OF FIGURES

2.1. Evolution from 1971 to 2005 of world total energy consumption ........................... 4

2.2. Role of greenhouse gases in global warming process .............................................. 5

2.3. World wind power capacity 1996-2008 .................................................................... 7

2.4. Wind turbines in different sizes ................................................................................ 11

2.5(a). Roof mounted micro wind turbine ........................................................................... 11

2.5(b). Pole mounted small wind turbine ............................................................................. 11

2.6. Rotor blades designs of small wind turbines ............................................................ 14

2.7. Breakdown of NHS England Carbon Emissions 2004 ................................................ 16

2.8. Graph of the NHS England CO2 emissions baseline and Climate Change Act targets 16

3.1. Map of Colthisall Station and Norfolk and Norwich University Hospital (NNUH) .... 20

3.2. Site and turbine data input for the Wind Yield Estimation Tool (WYET) .................. 21

3.3. Decision flow chart for determining the suitable roof mounted micro wind turbines 23

3.4. Illustration of energy output calculation process in the WYET................................. 24

3.5. A graphic of measured wind speed distribution and Weibull distribution ............... 25

3.6. Energy price rise in average annual household bills from 2003-2006 ...................... 27

4.1. Aerial map of Norfolk and Norwich University Hospital (NNUH) ............................. 29

4.2. Guidelines for siting of micro wind turbines ............................................................. 30

4.3. The Norfolk and Norwich University Hospital (NNUH) building site map ................ 31

4.4. Wind rose data of Coltishall weather station 2005 and 2004 .................................. 32

4.5. The variation trends of annual and seasonal mean wind speeds measured at the

Coltishall weather station from 2001 until 2005 ...................................................... 33

4.6. Aerial map of the Coltishall weather station (according to the postcode given in the

specification sheet from BADC) ................................................................................ 34

4.7. The annual mean wind speed estimation using the WYET ....................................... 35

4.8. Power curves micro wind turbines: (a) SWIFT 1.5 kW, (b) PowerSpin TSW 2 kW,

(c) PowerSpin TSW 3 kW, (d) Cleanfield 3.5 kW .................................................... 39

4.9. Wind power generation at various wind speeds for turbine PowerSpin TSW 3000 46

4.10. Payback period time at various wind speeds for turbine PowerSpin TSW 3000 ...... 47

vi

LIST OF TABLES

2.1. Initial proposed generation tariff levels for first year of FITs (2010-2011) ................. 9

2.2. Summary of Planning Guidelines suggested by the UK Government for the installation

of micro wind turbines ................................................................................................. 15

2.3. Proposed NHS England Strategies towards Carbon Reduction Targets ...................... 17

4.1. Annual and seasonal wind speed data 2001-2005 from the Coltishall station ........... 33

4.2. Beaufort scale of wind force ........................................................................................ 36

4.3. Potential suitable roof mounted micro wind turbines for the NNUH site................... 37

4.4. The noise ambient level ............................................................................................... 38

4.5. Potential yields of the chosen turbines calculated using the WYET ............................ 40

4.6. Financial analysis results of the first scenario (with CCL) ............................................ 41

4.7. Financial analysis results of the second scenario (with CCL and FITs) ......................... 42

4.8. Total annual energy cost saving for two different scenarios ....................................... 43

4.9. Payback period in years for two different scenarios ................................................... 43

4.10. Sensitivity analysis of varied wind speed for turbine PowerSpin TSW 3000 ............... 45

4.11. Sensitivity analysis of varied electricity tariff for turbine PowerSpin TSW 3000 ......... 48

vii

LIST OF APPENDIXES

1. Diagram Process ........................................................................................................... 60

2. Specification of Coltishall Weather Station ................................................................. 63

3. Annual and Seasonal Wind Rose Data of Coltishall Weather Station 2001-2005 ....... 64

4. Annual Wind Speed Distribution Data of Coltishall Weather Station 2001-2005 ....... 69

viii

LIST OF ABBREVIATIONS

BERR Department for Business, Enterprise and Regulatory Reform

BWEA British Wind Energy Association

CCL Climate Change Levy

DCLG Department of Communities and Local Government

DECC Department of Energy and Climate Change

DEFRA Department for Environment, Food and Rural Affairs

DTI Department of Trade and Industry

FITs Feed-In Tariffs

GBP Great Britain Pound sterling

GHG Greenhouse Gases

HAWT Horizontal Axis Wind Turbine

HMRC Her Majesty’s Revenue and Customs

IEA International Environmental Agency

LCBP Low Carbon Buildings Programme

LPA Local Planning Authority

NCIC National Climate Information Centre

NHS National Health Service

NNUH Norfolk and Norwich University Hospital

PLC Public Limited Company

SSWE Small Scale Wind Energy

UK United Kingdom

VAWT Vertical Axis Wind Turbine

WMO World Meteorological Organisation

WYET Wind Yield Estimation Tool

1

CHAPTER I

INTRODUCTION

1.1. Background

Carbon_dioxide emission, it has been argued, is the main cause of raising temperature on

earth (often described as the global_warming). Many researchers have linked the recent

increase in natural disasters and the extreme weather change with the global warming

phenomenon. Thus, the challenge of reducing carbon emission is recognised as important

both nationally and globally as a_means of tackling climate_change or global_warming

impacts. Accordingly, the United Kingdom (UK) Government has passed the recent Climate

Change Act 2008, which has carbon reduction targets of at least 26% of 1990 levels by 2020

and at least 80% of 1990 levels by 2050 (The UK Parliament, 2008).

As the largest organisation within the UK, in terms of employees and publicly funded health

service, the_National_Health_Service (NHS)_should become the_public sector leader in

sustainability and carbon reduction (NHS_Sustainable_Development_Unit,_2009). Hence, it

sets a target to reduce its 2007 carbon emissions by 10% by 2015 to comply with the UK

Government’s current Climate Change Act (NHS Sustainable Development Unit, 2009).

One of the main NHS strategies to achieve the target is by starting to reduce their onsite

building energy dependence on fossil fuel, and relying more on low carbon energy sources,

such as renewable energy (NHS Sustainable Development Unit, 2009). Renewable energy is

perceived as a key to future low carbon energy (BERR,_2008a). It can generate energy

without combustion reaction and emitting greenhouse gases particularly carbon dioxide. It

acts as a clean source of energy, hence it can help to reduce carbon emissions of the NHS

and meet the UK Government’s target for carbon reduction. Additionally, renewable energy

can save energy cost and ensure the security of energy supply in the future. Using a clean

energy source will also be in line with the core principle of the NHS, which is to provide good

healthcare for all people.

Micro wind turbines are being considered as one of microgeneration_renewable_energy

technologies that can potentially become clean energy sources for houses and buildings.

They are relatively easy to install and maintain,_comparatively cheap, low_cost in

maintenance,_simple and portable_(Hopkins,_1999;_Peacock_et_al,_2008;_Tavner,_2008).

2

Moreover,_they generally have harmless emissions and can be a reliable source if the

suitable wind resource is available within the proposed site (Carbon_Trust,_2008).

As the main healthcare services provider in the Norfolk County under the NHS management,

the Norfolk and Norwich University Hospital_(NNUH)_has_considered to install a roof

mounted micro wind turbine to reduce carbon emissions generated by the hospital’s

electricity use. Therefore, the_objective of this research is to study the feasibility of the

installation, whether it will be technically and economically viable for the NNUH, considering

the site characteristics and wind power resources in the hospital area.

1.2. Outline

Following on from this introduction, chapter two will review literature related to climate

change and the need for renewable energy, definition of renewable energy, and renewable

energy schemes in the UK. Furthermore, it will discuss about the micro scale wind energy

and the NNUH. At the end, it will outline the objective and aims of this research. In chapter

three, the methodology of this research will be described in detail. Chapter four will present

the results and discussion of the findings. Lastly, chapter five will cover the conclusions and

recommendations.

3

CHAPTER II

LITERATURE REVIEW

2.1. Climate Change and the Need for Renewable Energy

According_to the World_Meteorological_Organization_(WMO)_(Harrabin,_2008)_and_Met

Office (2009), the decade from 1998 to 2007 has been recorded as the warmest temperature

on the earth. Furthermore, the record shows that the global average surface temperature

has_risen by 0.74°C_over_the_last_decade. Climate_scientists at the Met_Office and_the

University of East Anglia predicted that the global temperature will continue to increase and

is expected to rise by between 1.8–4.0°C above 2005 levels by 2100, depending on future

greenhouse gases emissions (Met_Office,_2009).

Many researchers have argued that raising temperature on earth (or referred to as the

climate change phenomenon) and the rapid increase in natural disasters that has happened

globally over the last 30 years, are primarily caused by the increase in carbon dioxide

concentration in the atmosphere_(BWEA,_2007a;_Freris_and_Infield,_2008). Although,

carbon dioxide is not the most potent greenhouse gas, compared with methane and other

gases, it has enormous amount of significance in the atmosphere, due to multiple human

activities in consuming fossil fuel (Karl and Trenberth, 2003; Freris and Infield, 2008).

Carbon dioxide emissions are generated from combustion process of fossil fuel like coal and

oil, which contain carbon_(BWEA,_2007a)._Fossil_fuels have played important_roles in

providing energy globally for more than a century (Freris_and_Infield,_2008). Most recently,

global_economic_growth and_continuously_increasing population_coinciding, have_driven

energy demand to grow excessively (Freris_and_Infield,_2008). In_1973, world_total

consumption_of_energy_was_4,700_Mtoe (Million Tonnes of Oil Equivalent) or equivalent

to around 55000_TWh_(Tera_watt_hour) or 5.5 x 1016

_Wh_(Watt hour), where energy

conversion for 1_TWh is equal to 0.086_Mtoe and T for tera denoting 1012

(IEA,_2007).

In_2005, the total world energy consumption was 7,912_Mtoe or equivalent to about

92000_TWh or 9.2 x 1016

_Wh. There is an increased number of 3.7 x 1016

_Wh or equivalent

to 67.3% between 1973_and_2005._Freris_and_Infield (2008) predicted that the energy

demand worldwide will_still_grow due to explosion in customer electronics,_associated

industrial activities and widening access to consumers in the developing world. The

4

increasing world energy consumption is shown by the statistical data from the International

Energy Agency (IEA) Key World Energy Statistic 2007 in figure 2.1.

Source:_International Energy Agency (IEA) (2007), page 28.

Figure 2.1._Evolution from 1971 to 2005 of world total energy consumption

As global energy consumption is continuously growing,_consequently carbon dioxide

emission is also increasing._Carbon_dioxide is one of greenhouse gases which act like the

outside covering of a greenhouse, trapping outgoing radiation from the Earth to space (Karl

and_Trenberth,_2003;_IPCC,_2007). Outgoing heat radiation from the Earth’s surface to the

atmosphere is in the form of infrared energy or longwave radiation (Garratt_et_al,_1999;

IPCC,_2007). Longwave radiation is absorbed by greenhouse gases, hence, the concentration

of these gases is very important in determining how much energy the atmosphere absorbs.

On the other hand, incoming solar radiation, such as ultraviolet ray from the sun, is primarily

shortwave radiation which is transparent to greenhouse gases (Garratt et al, 1999; IPCC,

2007). Greenhouse gases do not absorb shortwave radiation. Thus, incoming solar radiation

passes through these gases, and is absorbed by the Earth and atmosphere. Figure 2.2

illustrates the role of greenhouse gases in global warming process.

An increasing amount of greenhouse gases in the atmosphere not only warm the Earth, but

also heat it up at a faster rate than ever before (Freris_and_Infield,_2008). Many scientists

believe that if the global community do not change the way they consume fossil fuel energy,

then_in the coming years natural catastrophes may become more severe_(and_more

frequent), and may completely disrupt the global economy along with countless lives (BWEA,

2007a). As a response to this menace, in 1997, the United_Nations (UN) agreed the Kyoto

Protocol in Japan_(UNFCC,_2009)._The protocol sets binding_targets for 37_industrialized

5

countries and the European community for reducing greenhouse gas (GHG) emissions by 5%

of 1990 levels over the five-year period 2008-2012 (UN, 1998; BWEA, 2007a; UNFCC, 2009).

Source:_IPCC (2007), page 115.

Figure 2.2._Role of greenhouse gases in global warming process

Reducing carbon emissions and meeting the Kyoto Protocol’s target are huge tasks for every

assigned country. One of main strategies to tackle carbon emission impacts is by starting to

replace the current dependence on fossil fuel energy sources with low carbon forms, such as

renewable energy. Renewable energy can generate clean energy without burning fossil fuel

and emitting carbon dioxide. Hence, it can reduce the amount of carbon dioxide and other

greenhouse gases in the atmosphere._Additionally, renewable energy can ensure energy

supply in the future when fossil fuels resources are predicted to last only for one hundred

more_years_(EIA,_2008)._According_to_a_new report from_the_Renewable_Energy_Policy

Network for the 21st

Century (REN21, 2009), renewable energy must play a major role in the

global energy supply to offset the possibility of worse environmental and economic threats

of climate change. The following section will discuss renewable energy in greater detail.

6

2.2. Renewable Energy

Renewable_energy is seen_as “essential contributors to the energy supply portfolio”_(IEA,

2007, p. 3) as they can contribute to secure future world energy supply, reduce dependence

on fossil fuel resources and mitigate greenhouse gases emissions (IEA,_2007)._Twidell_and

Weir (2006) define renewable energy as “energy obtained from natural and persistent flows

of energy occurring in the immediate environment” (p. 7). Furthermore, IEA (2002) explains

that:

Renewable energy is derived from natural processes that are replenished

constantly. In its various forms, it derives directly from the sun, or from heat

generated deep within the earth. Included in the definition is electricity and

heat generated from solar, wind, ocean, hydropower, biomass, geothermal

resources, and_biofuels_and hydrogen derived from renewable_resources.

(p.9).

According to EU Directive 2001/77/EC (EC, 2001),

Renewable energy sources shall mean renewable non-fossil energy sources,

which include wind,_solar, geothermal, wave,_tidal, hydropower,_biomass,

landfill gas, sewage treatment plant gas and biogases. (p. 3).

There are three renewable energy primary sources available on the earth, which are sun,

geothermal heat and gravitational forces. Solar radiation can be accessed directly using

solar thermal and photovoltaic technology, or indirectly in the form of wind, wave, hydro,

biomass and biofuels (Twidell_and_Weir,_2006). The average rate of solar radiation that

potentially can be exploited into energy is about 8000 times as large as the average rate of

world main energy consumption (Freris_and_Infield,_2008). Thus, the sun is by far the main

renewable energy source on earth.

On the other hand, the average available power from two other energy sources, which are

geothermal energy and gravitational forces, is much less of those from the sun (Freris_and

Infield,_2008)._Geothermal energy comes from the heat of the earth’s core which can be

extracted through thermal phenomena such as hot springs, volcanoes, geezers or boreholes

(Fridleifsson,_2001). Another main renewable energy source is energy in the tides formed

from the gravitational_fields of the_moon and the_sun which can be tapped using tidal

barrages or tidal stream technology (Twidell and Weir, 2006).

7

Renewable energy has grown significantly worldwide since 2004 (REN 21, 2009). Within four

years, from 2004 to 2008, solar photovoltaic (PV) capacity increased sixfold to more than 16

gigawatt (GW), wind power capacity increased 250% to 121 GW, and total power capacity

from new renewable energy technologies, such as small hydro, geothermal and biomass,

increased to 75% to 280_GW (REN 21,_2009). Wind power is leading the growth by 250%

increase in power capacity, as shown in figure 2.3. This trend is expected to continue with

falling costs of wind energy and increase in energy cost.

Source:_REN 21 (2009), page 11.

Figure 2.3._World wind power capacity 1996-2008

2.3. Renewable Energy Schemes in the UK

Energy supplies from renewable_sources have become_essential components of every

nation’s energy strategy due to environmental and sustainability energy concerns. In the UK

Government’s current energy policy, which was set out in the Energy White Paper of May

2007, renewable electricity is stated as the key_strategy to_tackle climate_change_and

implement cleaner sources of energy (DTI, 2007). The policy sets target to generate 10% of

the UK’s energy requirements from renewable sources by the end of 2010 and then 20% by

2020. It is expected that this target can deliver the UK to achieve its carbon reduction targets

of at least 26% of 1990 levels by 2020 and at least 80% of 1990 levels by 2050, in compliance

with the Kyoto Protocol on climate change (DTI, 2007).

In order to meet the Kyoto Protocol carbon reduction targets, the UK Government has also

decided to increase the rates of the energy tax, known as Climate Change Levy (CCL), to be in

line with inflation starting by April 2009 (HMRC, 2008). The Climate Change Levy is a tax on

8

the use of energy in industry,_commerce and the public_sector,_which was introduced in

2001_to encourage these sectors to reduce energy_use_and greenhouse_gases_emissions

(DEFRA, 2008). It exempts energy generated by renewable sources, so that businesses will

be encouraged to use renewable energy supplies (DEFRA, 2008).

According to energy statistics in 2007 from BERR (Department_for Business, Enterprise and

Regulatory_Reform)_(2008b),_only 2% of UK energy and under 5% of UK electricity comes

from renewable sources._Therefore, in order to be able to meet the UK renewable energy

target, the Energy White Paper has developed microgeneration strategy to encourage the

use_of_renewable_energy, particularly in individual households, communities_and small

businesses (DTI, 2007).

Microgeneration strategy was first established in 2006 by the UK Government with the aim

to create conditions where microgeneration could become_“a realistic alternative or

supplementary energy generation source” for individual households, communities and small

business (BERR,_2008c,_p. 1)._The term of microgeneration refers to small scale energy

generation, up to 50 kilowatt, from low carbon sources (EC, 2004; DTI, 2005). According to a

study conducted by Energy_Saving_Trust (EST), it is estimated that microgeneration has the

potential to supply 30-40% of the_UK’s_electricity needs and reduce annual household

carbon emission by approximately 15% (DTI, 2007).

The microgeneration strategy is supported by the Low_Carbon_Buildings_Programme

(LCBP), where_the government_provides grants to fund microgeneration_installations in

homes, communities, public_and private_sectors (DTI, 2005)._Furthermore, to provide

better support for this small scale renewable electricity generation within residential and

businesses sector, in April 2010, the UK Government will introduce a Feed-In Tariffs (FITs)

scheme, which might replace the current LCBP_scheme_(DECC,_2009a)._The FITs will

incentivise the electricity by microgeneration with a maximum limit of 5 megawatts (MW)

capacity, or equal to 50 kilowatts_(kW),_up to 20 years lifetimes of the technologies (DECC,

2009a)._The proposed financial incentives_are_listed in Table_2.1._For new projects, this

proposed tariff levels will be decreased by predetermined rates each year_(“degression”),

following expected falling costs of the technologies in the future_(DECC,_2009a)._At_the

moment,_the consultation is undertaken by the DECC_(Department of Energy and Climate

Change) to gain consultants and public opinion on the financial incentives schemes.

9

Various small scale renewable energy technologies are available for microgenerations. These

include_small wind turbines,_micro hydroelectric plants,_small scale photovoltaic solar

systems, and micro combined heat and power (The_UK_Parliament,_2004;_DTI,_2005;_DTI,

2007). In the UK, small scale wind turbines have been considered as a promising

microgeneration_technology, due to the potential of wind resources present in the UK. The

subsequent section will discuss small scale wind energy further.

Table 2.1._Initial proposed generation tariff levels for first year of FITs (2010-2011)

Source:_DECC (2009a), page 83.

10

2.4. Small Scale Wind Energy

Small wind power systems have a huge potential to be developed as clean energy sources

for houses and buildings within rural or urban area in the UK, due to the extensive wind

resources available in the UK (Sinden, 2005; Dale et al, 2003)._According to DECC (2009b),

the UK has the most intense wind energy resource in Europe, accounting of 40% of Europe’s

total wind energy. However, this potential resource is still mostly untapped and currently,

only 0.5% has been used to contribute to the UK’s electricity requirements (DECC, 2009b).

BWEA (2009) reported that since 2005, over 10,000 small wind turbines have been installed

in the UK_(p. 8)._It_is estimated that by 2020, over 600,000 small wind turbines will be

generating energy in the UK, based on the potential wind power resources,_future

technology cost reductions and increase in utility price (BWEA, 2009).

Wind is formed as a result of uneven heating of the Earth’s atmosphere by the sun (Twidell

and Weir, 2006). Wind can generate electricity by changing its kinetic energy into electrical

form using wind turbines (Gipe, 2004). Wind energy from wind turbines can produce clean

energy without pollution, once the turbine has built and installed (Carbon Trust, 2008). Thus,

wind turbines have strong potential to decrease carbon emissions associated with energy

use.

Previously, the development of wind turbines was focused, in the main, on the large scale

turbines with more than 50 kilowatt energy capacity, and rotor that can reach nearly 100

meters in diameter (Gipe, 2004). However, more recently small scale wind turbines have

been developed and their use is expanding in the UK as a result of increasing

microgeneration_demands in the domestic,_small industry and public sectors (Bahaj et al,

2007;_Peacock et al, 2008). Figure 2.4 illustrates wind turbines of different sizes.

Small scale wind energy (SSWE) covers generation of electricity by small wind turbines that

have rated power capacity up to 50 kilowatt (Bahaj et_al,_2007;_Carbon Trust, 2008). This

category is often subdivided into ‘micro’ and ‘small’ wind turbines (Carbon Trust,_2008).

Micro wind turbines cover turbines that have rated power capacity up to four kilowatt, while

‘small’ refers to turbines which have power rating above that threshold (Carbon Trust, 2008;

DTI, 2007).

11

Source:_Gipe (2004), page 9.

Figure 2.4._Wind turbines in different sizes

SSWE has more advantages than the larger ones in light of their “compactness, portability,

simple structure and low noise level in driving” (Hirahara et al, 2005, p. 1280). Hence, it can

be applied in various areas, such as urban areas, rural sites, and different types of buildings.

Small wind turbine is generally mounted on a pole and positioned in the backyard or on

rooftop of a house or building, to supply their electricity (Carbon_Trust,_2008;_EN,_2008).

Micro wind turbines are usually mounted 3 to 4 m above the ridge line a house or building,

or up to approximately 16 m in height with a free-standing pole (BWEA,_2009)._Figure 2.5

shows examples of a roof mounted micro wind turbine and a pole mounted small wind

turbine.

(a) (b)

Sources: (a) Renewable Devices Swift Turbines Ltd (2008); (b) Renewable Devices

Energy Solutions Ltd (2009).

Figure 2.5._(a) Roof mounted micro wind turbine; (b) Pole mounted small wind turbine

12

According to Carbon Trust (2008),_“In theory, SSWE has the potential to generate 41.3 TWh

of electricity and save 17.8 Mt [million_tonne] carbon_dioxide in the UK annually” (p._2).

However, given current high costs of small wind turbines and comparatively cheaper grid

electricity tariff, the installations of these turbines are still relatively low within householders

and businesses. Accordingly, although SSWE is technically feasible to reduce carbon emission

and pollution in those areas within the UK, yet the success of the economic outcomes is still

questionable._Additionally, environmental impacts, such as noise and visual impacts, and

difficulties in gaining planning permission are also factors that have hampered further

development of SSWE installation in the UK._The next section will discuss these issues in

more detail.

2.4.1. Issues related to Small Scale Wind Energy

There are four main issues which are often correlated to SSWE. They are wind power and

turbine’s performance, environmental impacts and planning permission of the installation.

Each of these matters will be discussed in following sections.

2.4.1.1. Wind Power and Turbine’s Performance

The suitability of SSWE in one particular area or building is principally determined by the

wind characteristics within the proposed site._Freris_and_Infield (2008) stated that “the

power in the wind that can be extracted by a wind turbine is proportional to the cube of the

wind speed” (p. 30), and is given in watts by wind power equation below:

P_=_1/2_ρ_A_V3_

Cp (1)

where_ρ is the air_density_(normally_1.225_measured_in_kg/m3 at average atmospheric

pressure_at_sea_level_at_15°C), A is the rotor swept area, V is the wind speed and Cp is the

power coefficient that represents the efficiency of the wind turbine.

The equation above shows that the energy content in wind will vary with the cube (the third

power) of the_wind speed. For_instance,_if the wind speed doubles_then the_estimated

energy generated will be approximately 23 or eight times as much energy as the previous

wind speed (Gipe, 2004). In further explanation, if the first wind speed is 4 m/s, where the

power output will be 43_(equal_to_64_watt),_and then the doubling of the wind speed to 8

m/s means power output will be 83_(equal_to_512_watt)._Both of these outputs_will_be

13

differentiated by exact eight times. As wind power is a cube function of the wind speed, a

10% increase in wind speed will result in approximately a 37% increase in the wind power

available from the wind (Gipe, 2004)._Hence,_the wind_speed_is very important for_the

amount of energy that will be produced by a wind turbine.

Nevertheless, wind is an intermittent source of energy which is determined by

meteorological_conditions and topographic factors,_for instance location_(longitude and

latitude),_terrain_shape, surface roughness, and local obstacles such as buildings and trees

(Mihelić-Bogdanić and Budin,_1992; Gipe,_2004;_and Met Office,_2008). Thus, it can only

generate power when the wind is blowing strongly enough._Obstacles like buildings and

trees can cause turbulence and will decrease the wind speed (Met Office, 2008).

Amongst other European countries, the UK has the most intense wind energy resources due

to its western location that is subjected to the main Atlantic weather fronts (Bahaj et al,

2007)._According_to Bahaj_et_al (2007),_the measured mean wind speeds at 50m above

ground level are around 6.5–7.5 m/s over a large area of the UK._However, SSWE is unlikely

to benefit from those favourable wind speeds as it is commonly placed in low altitude

location and possibly in dense urban terrain,_which_potentially experience significant

turbulence_(Bahaj et al, 2007).

Another substantial factor that will affect the power generation by wind turbine, as written

in the wind_power_equation_(1), is swept area._In accordance with the equation, power is

directly proportional to “the area of the wind stream swept by a wind turbine rotor”_(Gipe,

2004,_p. 485). To generate electricity, the rotor blades of wind turbine will catch the wind

that blows through them and use it to rotate the rotor (Hau, 2006). The rotor is connected to

generator, which will convert the kinetic energy in the wind into electricity (Hau, 2006).

Swept area of a turbine can be calculated using formula for the area that is suitable with the

turbine design._For a conventional wind turbine,_or commonly termed as horizontal axis

wind turbine (HAWT), the swept area is calculated using formula area of a circle which is A =

πR2, where R is the radius of the blade. For an H-rotor, the swept area’s formula using area

of a rectangle which is A = DH, where D is diameter and H is height of the blade. Lastly, for

Darrieus rotors, the formula that is used is A = 0.65 DH, which is a formula area of an ellipse

(Gipe, 2004)._H-rotor_and Darrieus rotors designs are also known as vertical axis wind

14

turbines (VAWT)._Figure 2.6 shows different rotor designs of small wind turbines that are

available in the current market.

Source:_Gipe (2004), page 61.

Figure 2.6._Rotor blades designs of small wind turbines

As swept area depends on the blades’ length and design, and power generated is directly

proportional to the swept area,_consequently, small wind turbines that have very small

diameter of blades will capture less wind power and hence generate lower electricity._Lower

energy_output_per_swept area from SSWE will eventually_result_higher energy cost_per

installed kilowatt and elongate the payback period time (Clausen and Wood, 1999; Hopkins,

1999).

2.4.1.2. Environmental Impacts and Planning Permission

One of the main barriers to the wider application of SSWE would appear to be related with

planning permission and its environmental impacts. At the moment, all installations of small

wind turbines still need consultation with the local authority regarding planning permission

(DECC,_2009c;_Planning_Portal,_2009)._However, it is expected that amended planning

legislation will be passed in the near future to permit installations of certain micro wind

turbines,_without the need to apply for planning permission (DECC,_2009c)._The proposed

guidelines for the permitted installation of micro wind turbines are listed in table 2.2.

There_are_a wide range of environmental impacts that need to be considered in the

installation of SSWE._From a planning perspective,_several issues that need to be looked at

include:

mounting_method, vibration, noise, colour and reflectivity, shadows and

reflections, access for installation and_maintenance,_electromagnetic and

electrical interference, physical damage, wakes [turbulences], driver

distraction, and bird and animal (bat) strike._(Peacock et al, 2008, p. 1325).

15

Among those impacts, the most significant ones that should be further considered are noise

and vibration, visual impacts, and animal strike. Small wind turbines are unlikely to have any

damaging impacts on electromagnetic and electrical interference, such as on aviation radar

or navigation systems,_television,_radio reception,_mobile phone reception or microwave

communications links, as they are usually mounted not higher than twenty metres (BWEA,

2007c; Peacock et al, 2008).

Table 2.2. Summary of Planning Guidelines suggested by the UK Government for the

installation of micro wind turbines

Rooftop Mounted Turbines Stand Alone Turbines

Wind Turbines on normal buildings permitted if: Wind Turbines on normal buildings permitted if:

• < 3 m above ridge (including the blade) and diameter

of blades < 2 m

• < 11 m (including the blade) high and diameter of

blades < 2 m

• internal noise < 30 dB • at least 12 m from a boundary

• external noise < 40 dB • internal noise < 30 dB

• "garden" noise < 40 dB • external noise < 40 dB

• up to 4 turbines on buildings > 15 (as with antennas) • "garden" noise < 40 dB

• vibration < 0.5 mm/s • vibration < 0.5 mm/s

No roof top mounted turbines will be permitted on

buildings in conservation areas or world heritage sites.

Stand alone turbines will be permitted besode buildings

in world heritage sites or conservation areas as normal

except in front of principal elevation.

Source:_Peacock et al (2008), p. 1325, adapted from DCLG (2007)

The main concerns of the public towards installation of small wind turbine are commonly

related to the sound emission_(AWEA,_2003;_Gipe,_2003;_Gipe,_2004)._They tend not to

oppose it, as they perceive the benefits of turbines to reduce their electricity bills and help

the environment (Gipe, 2004). However, if the noise has constituted nuisance and exceeded

permissible levels, where standard permitted levels is usually not more than 40 decibel, they

will complain to the local council and the council will order the owners to turn off their

turbines (Gipe,_2004;_Brooke, 2009). Thus, neighbourhood reaction towards small turbines’

noise will potentially affect how or when owners use their turbines (Gipe, 2004).

2.5. Norfolk and Norwich University Hospital

Norfolk and Norwich University Hospital (NNUH) is located to the south west of Norwich,

about four miles from the city centre. It has become the main centre of health services for

the_Norfolk_County’s_residences_since_2001,_and run under management of_the National

Health Service (NHS) Foundation Trust (NNUH, 2008).

16

The NHS is the main healthcare services provider for UK residents (more than sixty million

people),_and_one of the largest publicly funded health services in the world_(NHS, 2009).

Therefore,_to ensure effectiveness and efficiency of healthcare_services,_it uses a large

amount of resources which consequently causes significant environmental impacts,

especially in terms of carbon emissions (NHS England Carbon Emissions, 2008).

According to NHS England Carbon Emissions report (2008) as shown in figure 2.7,_the NHS

England in 2004 had carbon emissions of 18.6 million tonnes carbon dioxide, where 22% of it

has come from building energy, 60% from procurement and 18% from travel.

Source:_NHS Sustainable Development Unit (2009), page 30.

Figure 2.7._Breakdown of NHS England Carbon Emissions 2004

As the largest organization in the UK, the NHS should become the public sector leader in

sustainability and carbon reduction (NHS Sustainable Development Unit, 2009). Accordingly,

the NHS has set a target to reduce its 2007 carbon emissions by 10% by 2015 as part of the

strategy to meet the UK Government’s Climate Change Act targets (NHS_Sustainable

Development_Unit,_2009)._Figure 2.8 shows the NHS England projected emissions to 2020

with the NHS and governmental targets.

Source:_NHS Sustainable Development Unit (2009), page 9.

Figure 2.8. Graph of the NHS England CO2 emissions baseline and Climate Change Act targets

17

According to the NHS_England_Carbon_Emissions report,_procurement contributes the

highest percentage_(60%) in carbon emissions._However, a strategy to reduce carbon

emissions in the procurement sector poses considerable difficulties for implementation as it

comprises many different aspects,_such as the manufacture and transportation of NHS

purchased goods and services._Energy,_on the other hand, is less complex._Nonetheless, it

does not mean energy is an easy task to be dealt with, in order to meet the carbon reduction

target._Table_2.3 shows proposed NHS England strategies towards achieving carbon

reduction targets.

Table 2.3._Proposed NHS England Strategies towards Carbon Reduction Targets

Emission Sector Proposed NHS Strategy

Procurement Reduced unused pharmaceuticals

Smart/lean procurement of medical equipment

Smart/lean procurement of other expenditure

Building energy Onsite renewable electricity

Widespread measures to reduce electricity consumption

Increase Combine Heat and Power (CHP) to maximum potential by 2020

Travel Full implementation of smart travel plans across NHS estates

Source:_NHS Sustainable Development Unit (2009), page 34.

One of the main NHS England strategies to reduce carbon emissions is by starting to switch

onsite building energy dependence on fossil fuel to renewable energy. Renewable energy is

perceived as a key to future low carbon energy (BERR, 2008). It acts as a clean source of

energy (DTI, 2007), and hence can help the NHS to reduce carbon emissions and meet the

UK’s carbon reduction target._Furthermore,_renewable energy can save energy cost_and

ensure the security of energy supply in the future. Using a clean energy source will also be in

line with the core principle of the NHS that is to provide good healthcare for all people.

SERCO, plc (Norwich) which acts as non-medical services provider in support of the NNUH, in

areas such as grounds maintenance,_energy and utilities,_has proposed to install a micro

wind turbine on the rooftop of the hospital as one of energy solutions to produce clean

energy and reduce carbon emissions._They consider installation of a micro wind turbine as

relatively easy to install and maintain, comparatively cheap and low cost in maintenance._ _

For these reasons, this research will evaluate the potential of the installation of a micro wind

turbine at the hospital, whether or not the site is suitable for the installation, accounting for

18

factors such as the characteristics of the site and available wind sources. Furthermore, it will

estimate turbine’s performance in terms of energy_output,_carbon_saving,_and_financial

payback period. If the installation is likely to be feasible and consented by Local_Planning

Authority_(LPA),_it can benefit the hospital by saving its electricity costs and reducing the

carbon emission. Moreover, it could potentially encourage other businesses and houses in

the Norwich area to apply the turbines on their sites. Accordingly, developing more use of

renewable energy and helping the UK Government to achieve carbon reduction target. The

objective and aims of this research will be explained in the next section.

2.6. Objective and Aims

The objective of this research is to study feasibility of the installation of a roof mounted

micro wind turbine at the NNUH. The installation is proposed to directly supply the electrical

grid of a particular individual area rather than whole hospital area. The justification is

because it will be unreasonable for a micro wind turbine, which can only produce electricity

up to 50 kilowatt, to supply total hospital’s electricity consumption.

The objective of this research will be attempted by the following sub-aims:

� to assess the suitability of the proposed site for the installation

� to identify and choose the most suitable micro wind turbines to be installed

� to estimate annual energy yields and carbon saving of the chosen turbines

� to analyse cost-benefit and financial payback period of installing the selected turbines

The_proposed site locations and the performance of wind turbines are principal factors in

determining power output of the turbines._Thus, these two aspects are the main

justifications for this feasibility study.

19

CHAPTER III

RESEARCH METHODS

3.1. Methodology

A_roof mounted micro_wind_turbine has been proposed by SERCO, plc_(Norwich) to be

installed on_the rooftop of the NNUH._Hence,_the_research_was conducted to assess the

feasibility of the turbine’s installation at the NNUH. The feasibility study includes:

1. Assessment of the proposed site, including site survey, wind characteristics analysis and

determining the best position location for the installation,

2. Identification of the most suitable turbines to be roof mounted, with taking into account

the environmental impacts attached,

3. Estimation_of_annual energy_output of_the chosen turbines_and consequent_potential

saving in carbon emissions, and

4. Cost_benefit_analysis and estimation_of_payback_period, including sensitivity analysis of

the turbine’s performance,

The diagram of research process can be seen in appendix 1.

In order to estimate the local annual mean wind speed and the turbine’s performance, this

study is supported by wind estimator software called Wind Yield Estimation Tool (WYET),

which has been developed by the Carbon Trust and Met Office (Carbon Trust, 2009).

3.1.1. Assessment of the Proposed Turbine Site (the NNUH)

As Celik (2003) argued that, “If an autonomous wind system is to supply reliable electricity at

a reasonable cost in a given location, an accurate wind potential and wind energy

assessment_have to be carried out beforehand”_(p._694)._Assessment_of the proposed

turbine site was conducted to determine the wind power resources on the site and the site

suitability for a micro wind turbine installation. Activities that were carried out to achieve

these aims are site survey, building map analysis, and wind data collection from one of Met

Office weather station in_Coltishall_(BADC,_2009;_Habeebullah,_2009)._Additionally,_the

local annual mean wind speed was estimated using a wind estimator tool (the WYET).

20

10 mil

20 km

The_Coltishall_station was_located approximately_11.5 miles or 18.5_kilometres from the

NNUH,_see_figure_3.1._The station had measured weather various data since 1962 until it

closed down in February 2006. Coltishall station was considered to best represent the wind

condition in the NNUH as it was the closest anemometer station that measured the wind

hourly_at the standard_height of 10 metres in open terrain._Detailed specification of the

station can be seen in appendix 2.

Source:_Google Maps UK (2009).

Figure 3.1._Map of Colthisall Station and Norfolk and Norwich University Hospital (NNUH)

In this study, wind data from Coltishall station was collected from the year 2001 until 2005 (5

years measurement). The data is used for identifying annual and seasonal mean wind speed

and determining wind rose, a diagram showing the frequency and strength of winds from

different directions (Gipe, 2004), in the proposed location.

In order to estimate actual wind performance at the proposed site for installation of micro

wind turbines, the study also used the WYET from Carbon Trust (2009). The WYET uses wind

speed data from the Met Office National Climate Information Centre (NCIC), which consist of

long-term annual mean wind speed estimates for each one kilometre grid square area of the

UK, at the elevation of 10m above ground level and higher (Carbon Trust, 2008). As Carbon

Trust (2008) reported that “...NCIC takes into account 30 years of reading between 1971 and

2000 for approximately 220 sites.” (p. 12). Coltishall station is one of the Met Office weather

stations which had been included in the measurement long-term wind speed (BADC, 2009).

©2009 Google – Map data ©2009 Tele Atlas

Coltishall

NNUH

21

It is expected that by using NCIC data from the longer time period and the higher number of

stations,_more accurate_and_reliable prediction of actual wind measurements could_be

acquired (Carbon Trust, 2008).

Site and turbine details are required by the WYAT to estimate the local annual mean wind

speed. The site data needed are postcode or grid reference of the proposed turbine location

and the characteristic type of the site, such as open countryside, woodland, or high density

urban_(Carbon_Trust,_2009)._The ground roughness of the local site is derived from the

Centre for Ecology and Hydrology (CEH) and International Geosphere-Biosphere Programme

(IGBP) land cover maps (Carbon Trust, 2009). Furthermore, the tool will automatically select

the canopy height based on the selected site type, or the estimation can be input in the

canopy height box. “The_canopy is an area above the ground in which the wind will be

affected significantly by the height of obstructions such as trees and buildings”_(Carbon

Trust, 2009, p.4). Additionally, the mid rotor height from the ground or the canopy layer is

required to enable the tool estimating the wind speed data. In the WYET, the wind speed

data is corrected for terrain roughness,_the_canopy and the mid rotor heights using the

Prandtl aerodynamic boundary layer (Burton_et_al,_2001; Carbon Trust, 2009)._Figure 3.2

shows the input data needed for the tool.

Source:_Carbon Trust (2009).

Figure 3.2._Site and turbine data input for the Wind Yield Estimation Tool (WYET)

22

In this research, hospital site survey, aerial map and building map analysis were conducted

to identify the site characteristics, elevation of the buildings, the highest terrain and possible

obstacles in the surrounding areas. In addition, they were also used along with the Carbon

Trust’s turbine siting guidelines (2008) to determine the most suitable rooftop to install the

turbine. The best siting location should be on a strong constructed rooftop which has open

exposure to the strongest wind direction. Within this study, individual area of the NNUH that

will be supplied by the installed turbine should also be designated.

3.1.2. Identification of Suitable Turbines

At the moment, there are approximately 317 small wind turbines from 134 manufacturers

available in current_markets (Gipe,_2004; All_small_wind_turbines,_2009). From these

numerous products,_the_research had to select the proper micro wind turbines for

application in the NNUH.

There are several main aspects that should be considered in choosing suitable roof mounted

micro wind turbines._Firstly, the turbines must have rated power less than four kilowatt, in

accordance with the description of micro wind turbine in the White Paper on Energy (DTI,

2007),_and the amount of energy output should be appropriate to supply the electrical

consumption of_proposed individual area in the NNUH._Secondly,_the_turbine_should_be

suitable_for_roof_mounting._Not_all_turbines can be roof mounted due to weight and the

vibration impacts to building structure. Moreover, there are limited micro turbines that are

suitable to be roof mounted due to newly developed technology. Thirdly, the start-up wind

speed of the turbine should be lower than the annual and seasonal mean wind speed of the

local area._Otherwise, there will be some time, potentially in summer, at which the wind

turbine cannot work due to low wind speed_condition at_the turbine’s_site._This_will

significantly affect the energy output and consequently,_the economic performance of the

turbine._The last main aspect that needs to be considered is the significant environmental

impacts,_particularly related to noise emission,_which has to be less than 40 decibel,_and

visual impacts of the turbine installation._All of this_information,_including_the_turbines’

power_curve and estimated investment cost (cost of turbine, installation, maintenance and

operation), was obtained from the manufacturers’ websites and by contacting them by email

or phone. The decision flow chat process in determining the suitable turbines is shown in

figure 3.3.

23

Figure 3.3._Decision flow chart for determining the suitable roof mounted micro wind turbines

3.1.3. Assessment of the Turbine’s Performance

The essential factors affecting the decision whether to install a micro wind turbine are the

technical suitability and economic viability (techno-economic_feasibility) of the_turbines

in the proposed site._The_micro_wind_system is_determined_as_feasible,_if_it_generates

24

reliable electricity at a reasonable cost. Hence, over or under-estimated the turbine’s

performance should be avoided,_if the feasibility analysis of the installation is to be

conducted properly. Turbine’s performance was assessed by calculating and evaluating the

annual energy output, carbon saving and payback period.

3.1.3.1. Estimation of Annual Energy Output and Carbon Saving

The WYET was used to estimate the annual energy output and carbon saving. Firstly, the tool

needs the input data of the site’s characteristics and the planned height of the proposed

turbine to measure the wind resource in the local site, as explained in section_3.1.1

paragraph five. Furthermore, the tool also requires the power curve data, which is a graph of

the turbine power output at a range of wind speeds, of the chosen turbines (Carbon Trust,

2009).

In order to calculate the potential annual energy output from chosen turbines, the_WYET

uses a combination of data from wind_speed_distribution Weibull_model_and the power

curve from the selected turbine (Carbon Trust, 2009). This is the common method used by

meteorologists to determine the potential generation from a wind turbine in a commercial

wind_power_plant_(Gipe,_2004)._Essentially, the wind speed distribution, usually in unit of

hour per year, is matched with the power curve to find the number of hours per year the

turbine will be generating at various power levels (see figure 3.4).

Source: Carbon Trust (2008), page 28.

Figure 3.4. Illustration of energy output calculation process in the WYET

Turbine Power Curve

25

In the figure 3.4, the numbers figures above the bars show the number of hours in the year

of wind occurrence at that particular wind speed. For instance, shown in light blue colour is

the number of hours at 7 m/s. From the power curve, it can be seen that the turbine would

produce 0.17 kW at this speed. This_is_the combination methodology, of the Weibull wind

distribution model and the turbine’s power curve, that is used by the WYET to calculate the

energy output of a turbine (Carbon Trust, 2008).

Kreith and Goswami (2007) stated that the amount of energy that can be generated by a

wind_turbine_depends on_“the_average_amount of power available in the wind over a

specified period of time, commonly one year” (p. 19.37). Accordingly, potential wind power

resource and annual wind turbines’ energy yield will be relative to the frequency of wind

occurrence_at_various_speeds throughout one_year_(Celik,_2003;_Gipe,_2004;_Kreith_and

Goswami,_2007). The wind speed frequency distribution will vary at different places, hence,

the site wind speed distribution (the relative frequency of occurrences for each wind speed)

is very important in determining the available wind resource and the feasibility of the wind

turbine installation at the proposed site (Celik, 2003; Gipe, 2004; Kreith and Goswami, 2007).

The WYET uses the Weibull distribution model to estimate a wind speed frequency

distribution at the proposed turbine site,_where in this case is the NNUH. This method has

extensively been used to characterise wind resources for many decades_(Celik,_2003).

Research_conducted_by_Celik_(2003) shows_that_the Weibull wind distribution model_can

estimate wind energy output very accurately, with a calculated error of 2.79%, compared to

the_method_of measured wind data in time-series format._An example of measured wind

speed distribution and Weibull distribution are shown in figure 3.5.

Source:_EMSD Hong Kong (2006).

Figure 3.5._A graphic of measured wind speed distribution and Weibull distribution

26

To calculate the potential annual carbon dioxide saving from the installation of the turbine,

the_WYET assumes that the energy generated by the turbine displaces electricity from the

national grid (Carbon Trust, 2009)._Thus, the tool calculates carbon dioxide saving based on

emission conversion factor of_0.537_kgCO2/kWh, in accordance with the Defra’s GHG

conversion factor for the national electrical grid (DEFRA, 2007; Carbon Trust, 2009).

3.1.3.2. Cost Benefit Analysis and Estimation of Payback Period

Having obtained the annual energy yield using the WYET and the estimated investment cost

from the turbines’ manufacturers, it is possible to make an_economic_assessment_of_the

turbine installation. To estimate economic performance, information about electrical

consumption in the proposed area and the current electricity cost per kilowatt hour (kWh)

were also required._With_all_this information obtained,_annual energy cost saving and

payback period of the installation were calculated with the equations below.

Annual Energy Cost Saving (in £) = (3)

Annual Energy Output (in kWh) x Electricity Tariff (in £/kWh)

Total Annual Energy Cost Saving (in GBP) = (4)

(Annual Energy Cost Saving (in £)) + (Annual Energy Output (in kWh) x 0.00470 £/kWh*)

*) The rate of Climate Change Levy for electricity per kWh per 1 April 2009, based on the

inflation rate in April 2009.

Payback Period = Investment Cost (in £) (5)

Total Annual Energy Cost Saving (in £)

Subsequently, assessment on whether the installation would be economically viable or not,

was made based on_these_calculations._At the end,_the proposed FITs (table 2.1, page 9)

were also included in the calculation of total annual energy cost saving and payback period,

to see the economic performance of the turbine after the FITs scheme comes into effect in

April 2010.

27

3.1.3.3. Sensitivity Analysis

Sensitivity analysis was conducted to study the performance of the potential turbine if the

variables of wind speeds and electricity tariff (per kWh) are modified as below:

1. Wind speed was varied from 3.0-7.0 m/s. Wind speed will affect the power resulted by

the turbine significantly, as the wind energy will vary with the third power (cube) of the

wind speed (Burton et al, 2001; Gipe, 2004; Freris and Infield, 2008). Thus, sensitivity

analysis of turbine’s performance was conducted towards varied wind speeds, to see the

annual energy output in different wind speed.

2. Electricity tariff (per kWh) of main grid was varied from £0.10_(the current NNUH

electricity_tariff); £0.11 (10% increase); £0.14 (40% increase); £0.16 (60% increase); £0.18

(80% increase);_and_£0.20_(100% increase)._As oil prices continue to rise,_it is

predicted_that the electricity_bills in the UK will continuously increase_(Sharman and

Constable, 2008). In 2008 itself, electricity increases happened twice in a year with a total

increase_of_30% in monthly electrical bill_(UPW, 2008)._It was reported that for every

£100 spent on an electricity bill in January of this year, £130 was needed by October.

Furthermore, the increase of households’ annual bills from 2003 until 2006 is also

reported by the BBC News (2007), as can be seen in figure 3.6.

Source:_BBC News (2007).

Figure 3.6._Energy price rise in average annual household bills from 2003-2006

Previous feasibility studies on the wind turbine installation have demonstrated that the

increase in electricity tariff will make wind turbines perform better economically in the

higher_electricity_price_(Gipe,_2004;_Bahaj_et_al,_2008). Therefore, this study also

conducted the sensitivity analysis using varied electricity tariff, to see the implication of

increased electricity price on the turbine’s performance.

28

3.2. Limitations

The main limitation within this project would be the accuracy of wind data. Unless, there is

an actual wind speed measurement in the proposed site (which will require at least five to

ten years to collect), it is very possible that that the actual wind speed at the NNUH will be

different,_either_higher or lower,_with the wind speed estimated by WYET and Coltishall

weather station._However, this limitation was tried to be reduced by conducting sensitivity

analysis with_varied_wind speeds to estimate energy output in different wind conditions.

Additionally,_the turbine’s power curve data, which is the key to estimate annual energy

output, was only able to be obtained from the manufacturers. Consequently, there is a

possibility that they might exaggerate the turbines’ information sheets to sell their products

easier._Accordingly,_the research had to select accredited manufacturers which produce

accredited turbines products and provide warranty.

29

1000 ft

200 m

CHAPTER IV

RESULTS AND DISCUSSION

4.1. Assessment of the NNUH Site

Site survey, wind characteristics assessment, aerial map and building map analysis have been

conducted to determine the site suitability for a micro wind turbine installation. Results will

be presented and discussed in the following sections.

4.1.1. Site Profile

Site survey and aerial map analysis have been done to assess the NNUH’s site profile. NNUH

is located on the southern outskirts of Norwich. According to the site description in the

WYET (Carbon_Trust, 2009), the character of the NNUH’s site can be described as an open

countryside, as it is mainly surrounded by open lands with a few trees, see figure 4.1. The

WYET define an open countryside as a site where buildings and trees are widely spaced with

little urban infringement on the natural landscape. Locations that can be classified as an

open countryside are such as farms, small holdings and isolated buildings.

Source:_Google Maps UK (2009).

Figure 4.1._Aerial map of Norfolk and Norwich University Hospital (NNUH)

NNUH

30

4.1.2. Roof Mounted Turbine Siting Location

In_order to be in line with the NHS strategies on reducing carbon emissions, micro wind

turbine is proposed to be installed on the rooftop of the NNUH as an alternative renewable

energy source. It is obvious that a micro wind turbine, which defined by the DTI (2007) as

wind power system with rated power capacity less than 4 kW, will not have the capacity to

supply electricity for all hospital facilities, which annually need approximately 16 MW (mega

watt) (Serco, 2009a). Thus, Deli Cafe, which is located on Level 1 of the East Atrium Building

(see_figure_4.3), was proposed as the area in which the electricity will be supplied directly

by the turbine. The justification is because this area has its own electricity grid that can be

directly connected to the turbine power grid. Moreover, it is estimated that the electricity

demand of this small cafe (239.7m2) will still be possible to be supplied by the energy output

from the micro wind turbine, if the required wind resource is available within the NNUH site.

The annual mean electrical consumption of this cafe is approximately 6238.5 kWh (Serco,

2009a),_with electrical appliances used such as_refrigerators, freezers, electric_ovens,_a

dishwasher,_a microwave,_coffee machines,_a blender,_a cashier machine and lamps.

Subsequently,_further site survey and building maps analysis were conducted to determine

a suitable rooftop for the turbine’s installation, along with the turbine siting guidelines from

Carbon Trust (2008).

According to Carbon_Trust’s guidelines_(2008),_turbine should be mounted on a strong

constructed flat rooftop, preferably on concrete, which has an open exposure to wind from

all directions, particularly the prevailing wind. Additionally, it should be placed at the highest

point as practicably possible or allowed. Furthermore, it should be positioned above the

height of nearby trees, buildings or anything that could cause obstructions and turbulence to

the wind stream, at least higher 1 to 1½ times than the obstacle heights._Figure 4.2.

illustrates the guidelines that have explained above.

*) The arrows indicate wind direction

Source:_Carbon Trust (2008), page 23.

Figure 4.2._Guidelines for siting of micro wind turbines

Turbulence

effect of the air

stream caused

by the building

structure.

31

Based on the building site plan map from Serco (2009b), the highest building of the NNUH is

located in the centre block of the NNUH (see figure 4.3), with a height of approximately 13

metres above the ground level._The rooftop of this building is flat concrete with open

exposure to all wind directions. Moreover, this rooftop is close to the electrical grid of Deli

Cafe; they are in the same level but in different buildings and separated by a distance of

approximately 200_metres (see_figure_4.3)._Accordingly,_the_cable_installation_from_the

turbine grid to the cafe’s grid will be much easier and cheaper, and expected will not affect

the_hospital’s_activities under the rooftop._Therefore,_this rooftop was determined as a

suitable location to install the chosen micro wind turbine.

Source:_Adapted from the NNUH building site plan map (Serco, 2009b).

Figure 4.3._The Norfolk and Norwich University Hospital (NNUH) building site map

4.1.3. Site Wind Conditions

Wind conditions of the site should be assessed after determining the character of the

NNUH’s site and the suitable rooftop to mount the turbine. Wind speed and wind direction

Electricity grid

for the Deli Cafe

(Deli Cafe)

(The rooftop of the highest building)

32

are two essential factors in assessing the site suitability for the micro wind turbine

installation (Burton et al, 2001; Gipe, 2004; Bahaj et al, 2007; Carbon Trust, 2008). Ideally,

the actual wind speed and directions should be measured at the exact proposed turbine

location, as this will enable the most accurate energy output and carbon saving estimates to

be made (Gipe, 2004; Carbon Trust, 2008). However, it will need a considerable amount of

money and time, ideally ten years, to determine the wind speed distribution and wind rose

(direction) in the proposed location. Alternatively, the wind speed distribution and wind rose

can be estimated by existing sources of wind speed datasets, typically containing annual

mean wind speeds data. This study uses 5 years of wind speed datasets (2001-2005) from

Met Office weather station in Coltishall,_and the NCIC wind speed datasets from WYET.

These two methods have been further explained in section 3.1.1.

Firstly, the wind prevailing direction was determined from the Coltishall station’s wind

dataset. The 5 years annual and seasonal wind rose datasets were collected, and they show

that wind predominant direction mainly comes from the direction of west to southwest.

Figure 4.4 shows the examples of wind rose data from the two latest years, 2005 and 2004.

More data on annual and seasonal wind rose from 2001 until 2005 can be seen in the

appendix 3. The southwest direction is typical prevailing wind direction in the UK (Carbon

Trust, 2008). Based on this finding, the proposed rooftop should have an open exposure to

this prevailing wind direction, preferably to all wind directions. Site survey to this part of

NNUH’s rooftop was conducted, and the visual inspection confirmed that the proposed

rooftop has exposure to the predominant wind direction, see figure 4.3.

2005

Source:_Habeebulah (2009).

Figure 4.4._Wind rose data of Coltishall weather station 2005 and 2004

2004

33

Having obtained the wind rose, subsequently, wind speed within the site was also assessed

using datasets from the Coltishall weather station. Table 4.1 shows the annual and seasonal

mean wind speed data of the year 2001 until 2005 from the Coltishall station, and figure 4.5

shows the variation trends. Both table and figure show that during summer the wind speeds

were the lowest, while the highest were within winter months.

Table 4.1._Annual and seasonal wind speed data 2001-2005 from the Coltishall station

Year

Average Wind Speed (m/s)

Annual Winter Spring Summer Autumn

2001 4.4 4.9 4.6 3.8 4.7

2002 4.6 5.7 4.9 3.7 4.0

2003 4.2 4.7 4.4 3.6 4.0

2004 4.5 5.1 4.1 3.9 4.8

2005 4.4 5.4 4.4 3.6 4.2

Mean 4.4 5.1 4.5 3.7 4.3

*) Winter: December – February, Spring: March – May, Summer: June – August, and

Autumn: September – November.

Figure 4.5. The variation trends of annual and seasonal mean wind speeds measured at the

Coltishall weather station from 2001 until 2005

From Coltishall’s wind datasheets in table 4.1, the annual mean wind speed from five years

was measured at 4.4 m/s, with wind speed frequency distribution shown in appendix 4.

Although, the Coltishall_weather_station_measured the wind performance at the similar

type of location as the NNUH, which is an open countryside (see figure 4.6), it might not

actually represent the actual wind speed at the NNUH, as the measurement did not account

34

the presence of buildings as obstacles. The NNUH has several buildings within its complex

(see_figure_4.3), which can cause turbulence and hence will decrease the wind speed.

Furthermore, the turbine at the NNUH will be installed at the mid rotor height of 3 metres

above the building, in accordance with the proposed planning guidelines of micro wind

turbines installation in table 2.2 (page_15). Hence, in total the turbine will have mid rotor

height at 16 metres above the ground. While, the wind measurement at the Coltishall

station was done at the elevation of 10 metres above the ground. Consequently, there is 6

metres different between the measurement heights in the Coltishall station and proposed

mid turbine elevation at the NNUH. This will affect the accuracy of the estimated wind speed

at the actual conditions in the NNUH. Therefore, the second measurement using the WYET

was used to obtain more accurate wind speed data in the proposed turbine site.

Source:_Google Maps (2009).

Figure 4.6._Aerial map of the Coltishall weather station (according to the postcode given in

the specification sheet from BADC)

The WYET can give better estimation of wind speed data, because it can measure the wind

performance at any proposed turbine height, with also taken into account the site

characteristics and the canopy or obstacles heights in the surrounding. The tool estimated

the annual mean wind speed at the NNUH is 4.1 m/s, based on the input data of grid

reference or postcode, character of the proposed site, the canopy height (13 metres, which

is the height of the building), and the mid rotor turbine height (3 metres) (see figure 4.7).

500 ft

100 m

Coltishall Met Office

weather station

35

The result given by the WYET is different by 0.3 m/s, lower than the wind speed measured

by the Coltishall station. This might due to the factors of ground roughness and

obstacles/canopy heights which are accounted in the WYET’s wind speed calculation.

Source:_Carbon Trust (2009).

Figure 4.7._The annual mean wind speed estimation using the WYET

Wind speed of 4.4 m/s (Colthisall station’s measurement) or 4.1 m/s (the WYET’s calculation)

can be classified as low-moderate wind speed according to the Beaufort scale of wind force

(see table 4.2). Many researchers have studied that wind turbines usually need wind speed

of at least 4-5_m/s to start rotating, and 7_m/s average annual wind speed to generate

energy effectively (Burton_et_al,_2001;_Gipe,_2004;_BWEA,_2007c;_Carbon_Trust,_2008).

Nevertheless, as time passes, technology grows and develops. At the moment, there has

been some improvement in wind microgeneration technologies to develop roof mounted

turbines that are suitable for installation in the sub-urban and urban environment, which

36

generally has low wind speed. The following section will discuss the identification process of

selecting the most suitable micro wind turbines to be roof mounted at the NNUH.

Table 4.2._Beaufort scale of wind force

Wind speed (m/s) Beaufort description

0-1 Calm

2-4 Low

7-9 Moderate

12-14 High

Source:_Adapted from Gipe (2004), page 446.

4.2. Identification of Suitable Turbines

From the “All_small_wind_turbines” website_(2009), there are 317 small wind turbines

available on the current market. However, only turbines with rated power capacity less than

4 kW were selected, in accordance with the definition of micro wind turbines by DTI (2007).

Furthermore,_based on the power curve data obtained from the manufacturers, it was

estimated that only micro wind turbines with rated power capacity of 1.5 until 3.5 kW that

would be suitable to supply the electricity demand of the Deli_Cafe_NNUH (approximately

6238.5 kWh per year).

After the micro wind turbines with rated power capacity of 1.5 until 3.5 kW were selected,

their specifications were assessed further based on the start-up wind speed, weight,

vibration impact, noise emission, product design, maintenance requirements, life span, and

whether they are manufactured according to the wind turbine manufacturing standards

such as BS EN 61400-25 (BSI, 2009). Finally, only four most qualified turbines were chosen

from 52 micro wind turbines with rated power capacity 1.5-3.5 kW. They were selected

because they can be roof mounted on the top of the building; have start up wind speed less

than 4 m/s (estimated wind speed at NNUH site is around 4.1-4.4 m/s); free or have very low

vibration impacts; unlikely to have significant environmental impacts, according to the

proposed guidelines for the installation of micro wind turbines (DCLG, 2007, Peacock et al

2008); and meet the international standards of turbine manufacture. The four potential

suitable micro wind turbines that have been successfully determined using the methodology

in the section 3.1.2 are SWIFT 1500 watt (1.5 kW), PowerSpin TSW 2000 watt (2 kW),

37

PowerSpin TSW 3000 watt (3 kW), and Cleanfield 3500 watt (3.5 kW). The specifications of

these turbines are described in table 4.3.

Table 4.3._Potential suitable roof mounted micro wind turbines for the NNUH site

As the micro wind turbine will be mounted on the rooftop of hospital, the main aspects that

have to be considered from the installation are vibration and noise impacts to the sensitive

receptors, which in this case are the patients of the NNUH. According to the specification

sheets given by the turbines’ manufacturers, those four turbines are vibration free in low

and moderate wind speed. This is because they are equipped with anti vibration mounting

Turbine 1 2 3 4

Turbine name SWIFT 1.5 TSW 2000 TSW 3000 Cleanfield 3.5

Manufacturer Renewable Devices Technospin Inc. Technospin Inc. Cleanfield Energy

Energy Solutions Ltd

Type HAWT HAWT HAWT VAWT

Mounting system Roof/pole Roof/pole Roof/pole Roof/pole

Rated power 1500 watt 2000 watt 3000 watt 3500 watt

Capacity

Start-up 2.3 m/s 2.5 m/s 2.5 m/s 3 m/s

wind speed

Survival N/A 51 m/s 51 m/s 40 m/s

wind speed

Rotor diameter 2.1 m 3 m 3.8 m 2.75 m

Swept area 3.47 m2 7.07 m

2 11.34 m

2 8.25 m

2

Weight approx. 150 kg Approx. 100 kg Approx. 160 kg Approx. 130 kg

Noise emissions

<35 dB (across low to

strong wind speeds)

<40 dB (across low to

strong wind speeds)

<40 dB (across low to

strong wind speeds)

<40 dB (across low to

strong wind speeds)

Standard colour Black Green and White Green and White White

Temperature

range N/A -40C to +70C -40C to +70C N/A

Maintenance No No No Yes, but low

Poduct life 20 years Up to 30 years Up to 30 years 25 – 30 years

Warranty 5 years 5 years 5 years 5 years

Estimated cost £13,000 £7,000 £9,000 £11,000

Certification and BS EN 61000, BS EN IEC 61400-2 IEC 61400-2 CSA 22.2 No. 107,

standards 61400-2, BE 7671, IEC 61400-2, UL

and BS 5760-7. 1741, IEEE 1547.

Pictures

Specification

sheet or URL

website

http://www.renewable

devices.com/swift/

index.htm

http://www.allsmall

windturbines.com/

files/TechnoSpin_

ComSpin_C_2000.pdf

http://www.digital

guru.co.il/technospin/

images/stories/pdf/

Products/technospin_

powerspin_tsw2000_

3000_4000.pdf

http://www.clean

fieldenergy.com/

site/pdfs/CFSS0808-

1(s).pdf

38

system. However, this research predicted that the vibration attenuator might not work at

wind speed above the strong one (> 14 m/s) (the wind speed scale can be seen in table 4.2).

Nevertheless, as the wind datasets from the Coltishall station show that the NNUH site has

averagely low to moderate wind speed and some strong ones (but_less_than_14_m/s)

especially in the winter, it is predicted that the vibration impact of a micro wind turbine will

not be significant, either to the building structures or to the patients of the NNUH as the

sensitive receptors.

The noise emission is another main impact that has to be concerned from the roof mounted

micro wind turbine installation at the NNUH. Noise is defined by Therivel and Breslin (2001)

as “unwanted sound”. There are two types of sounds that are generated by wind turbines

(Rogers and Manwell, 2004; GEC, 2005). First is the aerodynamic sound which is produced

when the turning blades cut through the air, making a “whoosh” sound. Second is the

mechanical sound which is created by the movement of the gears and other mechanical

components._Nevertheless, as technology improves, the noise emissions of wind turbines

have been reduced significantly._For instance, the size, rotation speed and direction of

turbines’ blades have been modified to reduce aerodynamic sounds (GEC,_2005).

Additionally, better_acoustic_insulation has been used to reduce mechanical sounds (GEC,

2005). The noise ambient level for wind turbines can be seen in table 4.4.

Table 4.4._The noise ambient level

Source/Activity Indicative Noise Level (dB)

Threshold of hearing 0

Rural night-time background 20-40

Quiet bedroom 35

Wind farm at 350m 35-45

Car at 40 mph at 100m 55

Busy general office 60

Truck at 30mph at 100m 65

Pneumatic drill at 7m 95

Jet aircraft at 250m 105

Threshold of pain 140

Source:_BWEA (2000), page 1;_Rogers and Manwell (2004), page 6.

The turbines’_specifications, in_the_table_4.3, show that the four turbines have acoustic

emission levels less than 40 decibel (dB) at low until strong wind speed. Accordingly, based

on the noise ambient level shown in table 4.4, their sound is actually less than normal road

39

traffic or an office. For this justification, it is presumed that the installation of a micro wind

turbine at the NNUH will not have significant noise impacts to the patients, visitors and

people who work there.

4.3. Assessment of the Turbine’s Performance

The turbine’s performance in terms of energy output, carbon saving, and payback period,

were analysed using the WYET to assess the feasibility of the roof mounted micro wind

turbine installation at the NNUH.

4.3.1. Estimation of Annual Energy Output and Carbon Saving

Annual energy output and carbon saving from the four chosen turbines were estimated by

the WYET, using the input data of the site and turbine details (see figure 4.7). Power curve of

each turbine was applied to the measured local wind speed to calculate the annual

performance of the potential turbines. Power curve of each turbine are shown by figure 4.8.

Figure 4.8. Power curves micro wind turbines: (a) SWIFT 1.5 kW, (b) PowerSpin TSW 2 kW,

(c) PowerSpin TSW 3 kW, (d) Cleanfield 3.5 kW.

(a) (b)

(c) (d)

40

As shown in figure 4.8, although the Cleanfield (d) has the largest capacity of rated power

(3.5 kW), the TSW 3 kW (c) power curve’s shows the highest power output, where the

maximum output exceeds 4 kW at the rated wind speed 16 m/s. This is most likely to be

caused by the swept area of the turbines. The turbines’ specifications in the table 4.3 show

that PowerSpin TSW 3000 has a swept area of 11.34 m2, while Cleanfield’s has a smaller area

which is 8.25 m2. According to the wind power equation (page 12), the power generated by

wind turbine is directly proportional to the swept area. Thus, the larger the rotor blades (or

the swept area), the more power the turbine will generate (Burton et al, 2001; Gipe, 2004).

After the site details, turbine’s height and the power curve data have been inputted (see

figure 4.7), the WYET can estimate annual energy output and potential carbon dioxide that

can be displaced by the turbine. The potential yields of each of the turbines are shown in

table 4.5.

Table 4.5._Potential yields of the chosen turbines calculated using the WYET

Turbine 1 2 3 4

Turbine capacity (watt) 1500 2000 3000 3500

Site wind speed (m/s) 4.1 4.1 4.1 4.1

Annual energy output (kWh) 1,180 2,243 3,118 2,394

Annual Deli Cafe electrical consumption (kWh) 6,238.50 6,238.50 6,238.50 6,238.50

Percentage of energy saving (%) 18.91 35.95 49.98 38.37

Annual carbon saving (kg CO2) 634 1,204 1,674 1,285

Annual Deli Cafe carbon emission (kg CO2) 3350.075 3350.075 3350.075 3350.075

Percentage of carbon saving (%) 18.92 37.01 49.97 38.36

The results in table 4.5 show that turbine 3 (TSW 3000) gives the most significant annual

energy output. It can replace nearly 50% of the current dependence electricity on the main

grid and, consequently, reduce the carbon emissions attached. If the output is compared

with the total NNUH’s electricity consumption, which is approximately 16 MW per year, the

wind turbine will not affect significantly as it can only save approximately 0.02%, for both

energy demands and carbon emissions of the total hospital. However, as the focus of the

turbine’s installation is to supply one of the facilities in the NNUH (the Deli Cafe), and it can

potentially reduce 50% of electricity demand and carbon emission of the cafe, hence the

installation can be seen as a potential renewable energy source for the NNUH. Subsequently,

the economic feasibility of the installation of PowerSpin TSW 3000 will be analysed in the

following section.

41

4.3.2. Cost Benefit Analysis and Estimation of Payback Period

Having obtained the estimation of annual energy yield using the WYET, the economic

assessment of the potential turbine installation could be analysed. This was done by

calculating the financial indicators below (using equations in page 26):

1. Annual energy cost saving in GBP (£),

2. Total annual energy cost saving in GBP (£), and

3. Payback period in years.

The payback period estimation accounts for the investment cost (cost of turbine,

installation, maintenance and operation) and the performance of annual energy output of

the turbine. Turbines’ specifications in table 4.3 show that most manufacturers indicate the

turbines are maintenance free. However, a minimal 1% of the installed cost per annum has

been considered in the investment cost for breakdown cover including parts (Peacock et al,

2008). Furthermore, the total annual energy cost saving and payback period were assessed

based on two scenarios. The first scenario only accounted the sum of annual energy cost

saving and the Climate Change Levy (CCL) based on the inflation rate of April 2009. In the

second one, the proposed Feed-In Tariffs (FITs) (table 2.1, page 9) which will be prevailed in

April 2010, was added up in the total saving of the first scenario. The second scenario will

enable to see how this government grants scheme will affect the economic performance of

the micro wind turbine installation in the forthcoming years. The current NNUH’s electricity

tariff of £0.10 per kWh was used in the calculation of both scenarios. The results of financial

feasibility analysis of the first and second scenarios are demonstrated in table 4.6 and 4.7.

Table 4.6._Financial analysis results of the first scenario (with CCL)

Turbine 1 2 3 4

Turbine name SWIFT 1.5 TSW 2000 TSW 3000 Cleanfield 3.5

Annual energy output (kWh) 1,180 2,243 3,118 2,394

Annual energy cost saving (GBP) £118.00 £224.30 £311.80 £239.40

Exemption of CCL (GBP) £5.55 £10.54 £14.65 £11.25

Total annual energy cost saving (GBP) £123.55 £234.84 £326.45 £250.65

Annual Deli Cafe electrical bill (GBP) £623.85 £623.85 £623.85 £623.85

Percentage of annual energy saving cost (%) 19.80 37.64 52.33 40.18

Estimated investment cost (GBP) £13,000 £7,000 £9,000 £11,000

Payback period (years) 105.22 29.81 27.57 43.89

42

The results of the first scenario (table 4.6) show that only turbine 2 and 3 that could be

economically feasible, due to their estimated payback period which is less than their

expected lifetimes_(product_life time can be seen in turbines’_specifications in table 4.3).

However, turbine 3 was found to offer the lowest payback period amongst others. This

economic performance is consistent with the annual energy output and carbon saving

results that had been shown in previous section, where turbine 3 demonstrated the best

outcome by the potential to reduce approximately 50% of annual energy demand and

carbon emissions of the Deli Cafe in the NNUH.

Nevertheless, payback period of 27.5 years is still risky with an estimated turbine’s lifetime

stated by the manufacturer of “up to 30 years”. This statement indicates a possibility that

the turbine will stop working before 30 years. If it stops before the payback period (27.5

years), it means that the turbine installation will not be economically feasible, as the

buyer/user’s turbine still needs to pay for the rest of the investment cost without any output

generated from the turbine. Furthermore, there is a possibility that the estimated wind

speed will be different, either higher or lower, with the actual wind speed in the proposed

location. If the actual wind speed is lower than the estimated one, accordingly the turbine

will generate less electricity. As a consequence, it will make the payback period longer than

the estimated one.

Table 4.7._Financial analysis results of the second scenario (with CCL and FITs)

Turbine 1 2 3 4

Turbine name SWIFT 1.5 TSW 2000 TSW 3000 Cleanfield 3.5

Annual energy output (kWh) 1,180 2,243 3,118 2,394

Annual energy cost saving (GBP) £118.00 £224.30 £311.80 £239.40

Exemption of CCL (GBP) £5.55 £10.54 £14.65 £11.25

Initial proposed FIT (per kWh) *) £0.305 £0.230 £0.230 £0.230

Total FITs (GBP) £359.90 £515.89 £717.14 £550.62

Total annual energy cost saving (GBP) £483.45 £750.73 £1,043.59 £801.27

Annual Deli Cafe electrical bill (GBP) £623.85 £623.85 £623.85 £623.85

Percentage of annual energy saving cost (%) 77.49 120.34 167.28 128.44

Estimated investment cost (GBP) £13,000 £7,000 £9,000 £11,000

Payback period (years) 26.89 9.32 8.62 13.73

*) Proposed FITs for wind systems that generate electricity less than 1.5 kW is 30.5 pence

per kWh, and 23 pence per kWh for those which generate electricity between 1.5-15 kW

(see table 2.1, page 29). The FITs will only be paid up to 20 years lifetimes of the system.

43

The financial calculation of the second scenario (table 4.7) shows that the economic

performances of the turbines are significantly improved by the implementation of FITs as

financial incentives for the small scale low-carbon electricity generation (microgeneration).

As shown in table 4.8, with the inclusion of FITs, the total annual energy cost saving will

increase by 291.3% for the turbine that produce electricity less than 1.5 kW, and by 219.7%

for turbines that generate electricity between 1.5-15 kW. Moreover, table 4.9 shows that

the FITs will shorten the payback period by 74.4% for turbine less than 1.5 kW, and by 68.7%

for turbine with power output 1.5-15 kW. The difference outcome between turbine 1 and

the others is caused by the different FITs applied for the turbines with the electricity output

of 1.5 kW and turbines with output 1.5-15 kW.

Table 4.8._Total annual energy cost saving for two different scenarios

Turbine 1 2 3 4

Scenario 1 (CCL) £123.55 £234.84 £326.45 £250.65

Scenario 2 (CCL + FITs) £483.45 £750.73 £1,043.59 £801.27

Percentage of increase (%) 291.3 219.7 219.7 219.7

Table 4.9._Payback period in years for two different scenarios

Turbine 1 2 3 4

Scenario 1 (CCL) 105.22 29.81 27.57 43.89

Scenario 2 (CCL + FITs) 26.89 9.32 8.62 13.73

Percentage of reduction (%) 74.4 68.7 68.7 68.7

The findings from this feasibility analysis confirm Peacock et al (2008) and Martin’s (2006)

argument that “attaining a payback of 20 years for roof mounted turbines is impossible

without substantial grants” (Peacock et al, 2008, p. 1332). Martin (2006) also inferred that

expected payback period from the roof mounted turbine installation within 3 years are

unreasonable, unless the turbine is free of cost. With the FITs inclusion in the economic

assessment, most turbines, except turbine 1, become economically feasible to be installed.

This is because the FITs will subsidise the investment cost of the turbine by rewarding the

clean electricity that it generates. Accordingly, shorten payback period, and consequently

higher returns can be obtained.

Amongst other turbines, turbine 3 is still consistent showing the best performance. With the

inclusion of FITs, the turbine’s payback period becomes 8.62_years, which is the shortest

44

payback period compared to the other turbines. After the investment cost of the turbine is

paid off, the electricity that it generates will be free. Nevertheless, the electricity generated

will still be paid by the FITs until the first 20 years of the turbine operation, and be exempted

from the CCL. As a result, the free energy from the wind turbine can save the money for

paying electricity bills and generate profits. With the installation of turbine 3, it is expected

that the renewable electricity generated can gain annual revenue of £1,043.59 for

approximately 11 years. However, this estimated amount has not considered the inflation

factor, which is predicted to rise in forthcoming years. The inflation effect to the economic

performance of the turbine is difficult to be determined, due to the inflation rate that

changes every year; it can decline or increase. Most economic analysts predicted that the

inflation rate tends to increase, especially during recession that is happening at the moment.

Accordingly, as the CCL_value and electricity_tariff are in line with the inflation rate, it is

predicted that either the inflation factor will have no effect to the turbine’s economic

performance or it can bring more income to the installation of turbine.

4.3.3. Sensitivity Analysis

Based on the economic feasibility study that had been conducted, the income derived from

the wind turbine is affected by two essential factors, which are the annual energy output

and the value of the electricity generated. If it is assumed that electricity generated by the

turbine will displace the electricity that will be bought from the energy supplier, then the

value of the electricity generated by the turbine will be equal with the supplier’s electricity

retail rate (Gipe, 2004). In other words, the value of the clean electricity generated by the

turbine depends on the tariff of electricity. Moreover, the revenue that can be earned by the

turbine is also depends on the annual electricity generated by the turbine. The annual

energy output is mainly determined by the wind speed, because of the cube law in the wind

power equation (equation 1, page 12). Therefore, the sensitivity analysis on the wind speed

and electricity tariff was conducted to further assess the performance of the turbine. The

following sections will discuss the findings of the sensitivity analysis.

4.3.3.1. Varied Wind Speeds

The performance of the turbine will be mainly influenced by the amount of power that it

generates. In accordance with the wind power equation, the wind power that can be

45

converted into electricity by a wind turbine is proportional to the cube of the wind speed.

Hence, it is estimated that annual energy output will increase in cubic power proportion with

the higher wind speed. The sensitivity analysis on varied wind speeds was conducted to see

the annual energy output generated by the most favorable turbine (turbine 3, the PowerSpin

TSW 3000) in different wind speed conditions. Furthermore, it also estimated the economic

performance of the turbine using the scenario 2, accounting the FITs scheme which will be

implied momentarily in April 2010. The result of this analysis is shown in table 4.10.

Table 4.10._Sensitivity analysis of varied wind speed for turbine PowerSpin TSW 3000

Wind Annual CO2 Annual CCL FITs Total annual Payback

speed energy output saving energy cost exemption energy cost period

(m/s) (kWh) (kg) saving saving (years)

3.0 1,100 590 £110.00 £5.17 £253.00 £368.17 24.45

3.1 1,247 670 £124.70 £5.86 £286.81 £417.37 21.56

3.2 1,458 783 £145.80 £6.85 £335.34 £487.99 18.44

3.3 1,522 817 £152.20 £7.15 £350.06 £509.41 17.67

3.4 1,670 897 £167.00 £7.85 £384.10 £558.95 16.10

3.5 1,879 1,009 £187.90 £8.83 £432.17 £628.90 14.31

3.6 2,085 1,120 £208.50 £9.80 £479.55 £697.85 12.90

3.7 2,287 1,228 £228.70 £10.75 £526.01 £765.46 11.76

3.8 2,486 1,335 £248.60 £11.68 £571.78 £832.06 10.82

3.9 2,679 1,439 £267.90 £12.59 £616.17 £896.66 10.04

4.0 2,868 1,540 £286.80 £13.48 £659.64 £959.92 9.38

4.1 3,118 1,674 £311.80 £14.65 £717.14 £1,043.59 8.62

4.2 3,345 2,062 £334.50 £15.72 £769.35 £1,119.57 8.04

4.3 3,554 1,796 £355.40 £16.70 £817.42 £1,189.52 7.57

4.4 3,653 1,909 £365.30 £17.17 £840.19 £1,222.66 7.36

4.5 3,840 1,962 £384.00 £18.05 £883.20 £1,285.25 7.00

4.6 4,255 2,285 £425.50 £20.00 £978.65 £1,424.15 6.32

4.7 4,404 2,365 £440.40 £20.70 £1,012.92 £1,474.02 6.11

4.8 4,612 2,477 £461.20 £21.68 £1,060.76 £1,543.64 5.83

4.9 4,927 2,646 £492.70 £23.16 £1,133.21 £1,649.07 5.46

5.0 5,235 2,811 £523.50 £24.60 £1,204.05 £1,752.15 5.14

5.1 5,425 2,913 £542.50 £25.50 £1,247.75 £1,815.75 4.96

5.2 5,856 3,144 £585.60 £27.52 £1,346.88 £1,960.00 4.59

5.3 6,013 3,229 £601.30 £28.26 £1,382.99 £2,012.55 4.47

5.4 6,234 3,348 £623.40 £29.30 £1,433.82 £2,086.52 4.31

5.5 6,441 3,459 £644.10 £30.27 £1,481.43 £2,155.80 4.17

5.6 6,697 3,596 £669.70 £31.48 £1,540.31 £2,241.49 4.02

5.7 7,045 3,783 £704.50 £33.11 £1,620.35 £2,357.96 3.82

5.8 7,405 3,976 £740.50 £34.80 £1,703.15 £2,478.45 3.63

5.9 7,637 4,161 £763.70 £35.89 £1,756.51 £2,556.10 3.52

6.0 7,853 4,217 £785.30 £36.91 £1,806.19 £2,628.40 3.42

6.1 8,241 4,425 £824.10 £38.73 £1,895.43 £2,758.26 3.26

6.2 8,416 4,579 £841.60 £39.56 £1,935.68 £2,816.84 3.20

6.3 8,737 4,692 £873.70 £41.06 £2,009.51 £2,924.27 3.08

6.4 9,024 4,846 £902.40 £42.41 £2,075.52 £3,020.33 2.98

6.5 9,404 5,050 £940.40 £44.20 £2,162.92 £3,147.52 2.86

6.6 9,629 5,171 £962.90 £45.26 £2,214.67 £3,222.83 2.79

6.7 9,934 5,335 £993.40 £46.69 £2,284.82 £3,324.91 2.71

6.8 10,205 5,480 £1,020.50 £47.96 £2,347.15 £3,415.61 2.63

6.9 10,371 5,569 £1,037.10 £48.74 £2,385.33 £3,471.17 2.59

7.0 10,525 5,652 £1,052.50 £49.47 £2,420.75 £3,522.72 2.55

46

As seen in table 4.10 and figure 4.9, annual energy output increases with the increasing wind

speed, following the wind power equation that turbine’s power output equals to cubic

power of wind speed (Poutput V3

wind). The electrical consumption of the Deli Cafe in the

NNUH is averagely 6,238.5 kWh per year. If the NNUH wants the turbine to supply the total

electrical demands of the_Deli_Cafe, so that it does not need to depend on the energy

supplier at all, the minimum wind speed required is 5.5 m/s with expected annual energy

output is 6,441 kWh. With this amount of energy output, the turbine can fulfil the electricity

needs of the cafe, and the excess can be exported to other electricity grids to supply other

areas within the NNUH. However, according to the WYET calculation, to obtain wind speed

of 5.5 m/s in the NNUH site, the turbine should be mounted in the elevation of 40 metre

above the building, which is impracticable to be done.

Figure 4.9._Wind power generation at various wind speeds for turbine PowerSpin TSW 3000

Nevertheless,_in order to be feasible,_a turbine does not have to have the capability to

supply the total demand of the electricity._As long as it is able to generate reliable clean

electricity to reduce carbon_emissions attached to the use of fossil fuels and its payback

period is less than its expected lifetimes, the installation turbine can be considered as

feasible. For turbine PowerSpin TSW 3000 that has estimated lifetimes up to 30 years, wind

speed_condition that can be regarded as feasible_for its installation are those which are

capable of achieving payback within less than its life span. As shown in figure 4.10, the wind

Annual electrical consumption of the Deli Cafe 6238.5

47

speed as low as 3 m/s in the NNUH site can still be feasible for the installation turbine with

scenario 2 (the economic assessment which accounts for exemption of CCL and FITs

incentive), because its estimated payback period is less than 25 years. The higher the wind

speed, the more electricity could be generated, and accordingly the shorter payback period

of the turbine installation.

Figure 4.10._Payback period time at various wind speeds for turbine PowerSpin TSW 3000

4.3.3.2. Varied Electricity Tariff

Another factor that has been argued to play a major role in determining the performance of

the turbine, particularly economic, is the electricity tariff (Gipe, 2004; Bahaj et al 2008). The

electricity rate will influence the value of the electricity that turbine produces and

consequently the payback period of the turbine installation (Gipe, 2004).

The rising price of electricity has been intensely debated since nearly forty years ago, when

the utility rates escalated sharply in the 1970s because of the two oil embargoes (Gipe,

2004). Analysts believe that the energy price will continue to increase due to the diminishing

of fossil fuel resources (oil in particular), and the increasing global energy demand as the

impact of the continuous growth of human population (IEA, 2007; Freris and Infield 2008).

Accordingly, as the electricity rate is subject to the oil price, it is predicted that the electricity

PowerSpin TSW 3000 Life Span

48

tariff will continuously increase in line with the rising of oil prices (Freris and Infield, 2008;

Sharman and Constable,_2008). Additionally, another main factor of electricity rate

escalation is its relationship to inflation (Gipe,_2004)._Economic analysts generally define

inflation as a rise in the general level of prices of goods and services in an economy over a

period of time (Schwartz, 2009). OECD (2009) has predicted that with the inflation rates tend

to increase, especially during current recession time, the electricity price will increase as

well.

In order to see the effect of the predicted increased electricity cost on the turbine’s

economic performance, a sensitivity analysis using various electricity tariffs was conducted

within this research. It used the economic calculation using scenario 2 at the estimated wind

speed of the NNUH site (4.1_m/s), along with five different tariffs which are £0.10

(represents the current NNUH electricity tariff); £0.12 (20% increase); £0.14 (40% increase);

£0.16 (60% increase); £0.18 (80% increase) and £0.20 (100% increase). The analysis result is

shown in table 4.11.

Table 4.11._Sensitivity analysis of varied electricity tariff for turbine PowerSpin TSW 3000

Electricity Increase AOE (*) Annual CCL FITs Total Annual Increase Payback

Tariff Electricity (kWh) Energy Cost Exempt

Energy Cost Saving Period

per kWh Tariff

Saving

Saving

(years)

£0.10 0% 3,118 £311.80 £14.65 £717.14 £1,043.59 0% 8.62

£0.12 20% 3,118 £374.16 £14.65 £717.14 £1,105.95 6% 8.14

£0.14 40% 3,118 £436.52 £14.65 £717.14 £1,168.31 12% 7.70

£0.16 60% 3,118 £498.88 £14.65 £717.14 £1,230.67 18% 7.31

£0.18 80% 3,118 £561.24 £14.65 £717.14 £1,293.03 24% 6.96

£0.20 100% 3,118 £623.60 £14.65 £717.14 £1,355.39 30% 6.64

(*) AOE: Annual Energy Output

As seen in table 4.11, with the increase of electricity tariff, the value of the electricity

generated by the turbine will rise as well. The calculation shows that every increase of the

electricity tariff by_20% will increase the annual energy cost saving by 6%. Consequently,

higher returns can be obtained and shortens the payback period of the installation.

In this calculation, the value of the Climate Change Levy (CCL) exemption was used based on

the UK inflation rate in April_2009, which is 2.5% according to the UK National Statistics

Online (NSO,_2009). In accordance with the UK Government’s amended legislation in the

49

Finance Bill 2008, the rates of CCL will be revised annually in line with the inflation (HMRC,

2008). As the future annual inflation rate always changes and hardly to be estimated

precisely, this research only accounted the CCL exemption based on the UK inflation rates in

April 2009. Nevertheless, this study has demonstrated the implication of the increase

electricity tariff to the value of the electricity generated by the turbine and to the overall

turbine’s economic performance.

4.4. Summary

The results of the_feasibility analysis of a proposed roof mounted micro wind turbine

installation at the NNUH have been presented and discussed in this chapter. The research

had successfully determined the potential wind resource at the NNUH site, and the technical

and economic performance of the most suitable turbine by using the WYET software, which

has been developed by the Carbon Trust and Met Office. Subsequently, the final chapter will

summarise the entire findings of this feasibility study and state the conclusion reached, as

well as propose recommendations for the further study.

50

CHAPTER V

CONCLUSIONS AND RECOMMENDATIONS

5.1. Conclusions

A feasibility study of the installation of micro wind turbine on the rooftop of the NNUH has

been presented in this research. Site survey and wind characteristics assessment, as well as

building site and aerial map analysis had been conducted to assess the suitability of the

NNUH as the proposed site for roof mounted micro wind turbine installation. Additionally,

the most suitable turbine to be installed had been selected. Its performance and economic

viability have been determined using Wind Yield Estimation Tool (WYET), which has been

developed by the Carbon Trust and Met Office (Carbon Trust, 2009). The results obtained

indicated that the installation of a roof mounted micro wind turbine will be appropriate for

the NNUH, when the proposed FITs scheme is applied in April 2010 (DECC, 2009a).

The research presented here has highlighted some key issues which are likely affecting the

feasibility of the micro wind turbine installation. The principal factor that should be

considered is the availability of sufficient wind resource at the proposed site, which will be

converted by the turbine to produce power. In other words, the wind speed is the main

factor affecting the amounts of electricity generated and carbon saved by wind turbines.

Annual mean wind speed at the NNUH site is estimated to be 4.4_m/s, according to

measurement of five_years (2001-2005) wind datasets from Coltishall weather station, and

4.1_m/s,_based on the WYET estimation. According to the Beaufort wind force scale, this

range of wind speed is classified as low to moderate wind speed. Previously, wind turbines

usually required wind speed of at least 4-5 m/s to start rotating, and 7 m/s average annual

wind speed to generate energy effectively. Nevertheless, today, with the rapid improvement

in wind turbine technologies, better design of micro wind turbines have been developed to

produce energy at low wind speed. For instance, PowerSpin TSW 3000, which was selected

in this research as the most suitable micro wind turbine to be installed on the rooftop of the

NNUH building, requires low wind speed at 2.5 m/s to start rotating. With the wind speed

condition at the NNUH site, which is estimated at 4.1 m/s by the WYET, the WYET calculated

that the turbine is capable to generate power that can supply nearly 50% of the electricity

required by a main cafe at the NNUH. Consequently, the turbine has the potential to reduce

51

50% of carbon dioxide emission generated by the current_electricity_source, which is

obtained from the main grid.

The improvement in the small wind turbine technology has happened because there are

increasing demands to develop rooftop installations that are suitable for buildings in the

urban environment, which generally has low wind speed (Peacock et al, 2008). Furthermore,

as technology improves, the size, rotation speed and direction of turbines’ blades have been

modified to reduce aerodynamic sounds (GEC, 2005). Additionally, better acoustic insulation

has been developed and equipped in the micro wind turbine. Accordingly, the vibration and

noise emissions of wind turbines have been reduced significantly. Moreover, as time passes,

the costs of wind technologies have become cheaper, and hence, the turbines can perform

better economically.

After calculating the turbine energy yields using the_WYET, another key parameter in

determining the feasibility of the wind turbine installation is the economic performance of

the chosen turbine. In this study, the economic performance of the turbine is mainly

determined by the payback periods of the chosen micro wind turbine. Calculating the

payback period, or the time required for an investment to pay for itself, is an easy method to

appraise the economic viability of the turbine installation (Gipe, 2004). Simply divide the

investment cost (cost of turbine, installation, maintenance and operation) of the micro wind

turbine by its estimated revenue. If the payback period is less than the turbine’s lifespan, the

turbine can be considered as feasible_economically. Therefore,_the_shortest_payback is

preferred, to maximise the economic benefits of wind energy system installation.

With only Climate Change Levy (CCL) exemption was taken into account, the payback period

of the chosen turbine (PowerSpin TSW 3000), which has 30 years life time, is nearly 28 years.

However, with the CCL exemption and the proposed FITs scheme, which will be introduced

in April 2010, the turbine’s payback period becomes 8.62 years. The results show shorter

payback period will be obtained with the implementation of the FITs scheme. Thus, the roof

mounted micro wind turbine is more appropriate to be installed at the NNUH, when the FITs

scheme has come into effect next year.

Another essential factor affecting the feasibility of the wind turbine installation is increasing

electricity tariff, which has been influenced by the fluctuation of oil price and the inflation.

52

According_to Gipe (2004), utility rates influence the_value of the electricity that turbine

produces, and consequently the economic performance of the turbine installation. The same

outcome as Gipe’s_theory was obtained in this research, where the higher_utility_price

increases the annual energy cost saving, and accordingly shortens the payback period of the

wind turbine installation.

In summary, the study has demonstrated that the proposed micro wind turbine installation

on the rooftop of the NNUH is technically feasible and economically viable as an alternative

renewable energy source to generate clean energy and mitigate carbon emissions, as well as

reduce energy bills. Better performance of the turbine installation can be achieved by

advances in wind_turbines_design, increasing energy prices and the financial incentives

provided by the government.

5.2. Recommendations

The WYET that had been used in this research only provides initial qualitative estimations of

the NNUH site’s potential. To obtain the greatest degree of certainty about potential yields

and carbon savings, actual wind measurement using anemometry equipment for at least one

year duration should be conducted. If the actual measurement shows the similar wind trend

as the estimated ones, then the project could be proceed forward. Nevertheless, if the costs

of the actual wind measurement (including hiring a consultant) are about the same cost as

the turbine’s, buying and installing turbine will be better opted. With this way, the user can

monitor the turbine’s actual energy generated and wind regime at the site, while in the

meantime the power generated can be used to supply the electricity of the site, and hence

can reduce cost for energy bills, and importantly decrease the carbon emission attached to

the fossil fuels consumption. In addition, the impact of wind turbine on technical aspects,

such as the stability of the wind turbine, the quality of power generated, and the efficiency

of turbine should be monitored thoroughly. These services are commonly provided by the

turbines’ manufacturers, included in their warranty offer. Finally, the environmental impacts

of the turbine on sounds, vibrations, public safety and visibility should also be checked

regularly after finished installation.

53

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APPENDIX

Appendix 1. Diagram Process

Figure 1. Diagram research process of the feasibility study

Figure 2. Diagram process to achieve objective 1 (the suitability of the proposed site)

Figure 3. Diagram process to achieve objective 2 (choosing the suitable turbines)

61

Figure 4. Diagram process to achieve objective 3 (annual energy output and carbon saving)

Figure 5. Diagram process to achieve objective 4 (annual energy cost saving and payback

period)

62

Figure 6. Diagram process to achieve objective 5 (sensitivity analysis of turbine’s performance)

63

Appendix 2. Specification of Coltishall Weather Station

Title Coltishall

Location Coltishall

Easting 626200

Northing 322900

Grid Reference TG 262229

Postcode NR10 5

Elevation 10 m

Type Synoptic

Owner Met Office

Start Date 01/01/1962

End Date 01/02/2006

Measurement Hourly

*) Sypnotic weather observation means a surface weather observation made at periodic

times, usually at three hourly and six hourly intervals.

Source: http://badc.nerc.ac.uk/cgi-in/midas_stations/search_by_name.cgi.py?name=coltishall

64

Appendix 3. Annual and Seasonal Wind Rose Data of Coltishall Weather Station 2001-2005

Annual 2005 Autumn 2005

Spring 2005 Summer 2005

Winter 2005

65

Annual 2004 Autumn 2004

Spring 2004 Summer 2004

Winter 2004

66

Annual 2003 Autumn 2003

Spring 2003 Summer 2003

Winter 2003

67

Annual 2002 Autumn 2002

Spring 2002 Summer 2002

Winter 2002

68

Annual 2001 Autumn 2001

Spring 2001 Summer 2001

Source: Habeebullah, 2009.

Winter 2001

69

Appendix 4. Annual Wind Speed Distribution Data of Coltishall Weather Station 2001-2005

2005 2004

Source: Habeebullah, 2009.

2001

2003 2002