Introduction to Combined Heat and Power 22nd Sept 09 North …research.ncl.ac.uk/pro-tem/components/pdfs/material... · 2012-06-21 · Introduction to Combined Heat and Power 27th

1

27 Oct 11 Combined Heat and Power

Introduction to Combined Heat and Power

27th Oct 11 Newcastle

Rob Gwillim Energy Consultant


Topics

• Background

• What is Combined Heat & Power (CHP)?

• Types of CHP

• Fuels

• CHP Policy & Quality Assurance

• Case Studies (Large Scale CHP)

• Micro CHP

• Conclusions

2


What is Combined Heat & Power?

• Combined Heat & Power (CHP) - recovery of

heat produced when generating electricity

(usually wasted)

• The fuel can be natural gas, LPG, biomass, gas

derived from anaerobic digestion or land fill and

oils

• Most CHP schemes in the UK use natural gas


CHP Energy Balance

Source GPG 388

80%

40% 80%

3


Power to Heat Ratio

In practice

• Power to heat ratio and efficiency changes with

scale and technology

• Heat output follows electrical output

• Best systems operate close to 90%

• Technology and load profile all have an effect


CHP Cost Benefit

Source GPG 388

80%

40% 80% X 3p

=£3

X 3p =£1.68

X 10p =

£3.50 Potential Saving =£2.18

4


CHP Costs

• CHP can save money

• The CHP has to be operating for savings to be

achieved

• Both heat and electricity will have to be used

• Operational reliability needs to be maximised

• Maintenance costs will need to be minimised


CHP CO2 Benefit

Source GPG 388

80%

40% 80% X 0.19

=19kg

X 0.19 =10.6kg

X 0.56

= 19.6kg

Potential Saving =11.2kg

5


CHP CO2 Savings

• CHP can save CO2

• The CHP has to be operating for savings to be

achieved

• Both heat and electricity will have to be used

• As carbon intensity of electricity falls savings will

decrease.

• If boiler efficiency is higher than 80% then

savings will be less.


CHP Technologies

• With the exception of fuel cells all system are

made up of a prime mover

• Either an engine or a turbine which drives-

• A generator to produce electricity

• A heat recovery system

6


Large Scale Steam Turbine 2MWe +

• Heat can be recovered

from steam turbines

• Electrical efficiency

typically 20-25%

• Compromised due to the

high output temperature

of steam 150-180oC

• Larger scale improves

efficiency

4-500oC

60oC 150oC


Sheffield Waste to Energy

• Sheffield Energy from

Waste

• 19MWe -39MWth

• Consumes 225,000

tonnes of waste

• Feeds into a 44km

district heating network

• With 140 buildings

connected

7


Gas turbines >2 MWe

• Large scale

• High exhaust gas temperature can be used to

raise steam

• Electrical efficiency 25-35%

• Poor part load efficiency

450-500oC


Gas turbines Nestle York

• Natural Gas fire turbine

• Typically 12 MWe

• 25% electrical efficiency

• 45% thermal efficiency

• H:P 1.8:1

8


Internal Combustion Engines

• Uses a conventional spark or

diesel ignition engine

• Any liquid or gaseous fuel

typically natural gas

• Electrical efficiency decreases

with smaller scale

• Good modulation and part load

efficiency down to 50%

• Can potentially be used as

standby generation

• Require regular maintenance

30% Electrical

25% Jacket Cooling

25% Exhaust Cooling


SAS Radisson Hotel Liverpool

• 206kWe=30%

• 324kWth =50%

• H:P=1.6:1

• Provides heat for

swimming pool,

space and water

heating

• Roof mounted

(Courtesy of Ener-G and Radisson)

9


Huntingdon Leisure Centre

• 70kWe=31%

• 104kWth=46%

• H:P=1.5:1

• Provides space and water

for leisure centre heating

• 1 boiler removed in plant

room to make space


Micro Gas Turbine

• Typically 30-1000kWe

• 20-27% electrical

efficiency

• Heat : power=1.5-3:1

• Power turndown so

multiple units used

• Require gas at 5bar so

gas booster required

• Long service intervals

Source Capstone

10


Foot Print

Table of typical sizes and weights for packaged CHP units

Gas-engine CHP Small-scale gas

turbine CHP

Electrical output (kW)

60 100 300 600 1,000 60 100

Heat output (kW)

115 130 430

880

1,300 100 150

Fuel consumption (kW)

215 310

990

1,950

3,000

280

350

Length (m) 2.9 2.9 4.0 6.5 8.0 2.0 2.9

Width (m) 0.8 1.3 2.0 3.5 4.0 0.9 0.9

Height (m) 1.8 1.95 2.4 2.6 3.5 1.6 1.9

Package weight (t)

2.5 4.0 8.0 12.0 16.0 1.0 2.0

Source DEFRA


Relative Efficiency

Source DEFRA

11


Fuel Cells

• Early system now coming to market

• Require a hydrogen fuel usually derived from

natural gas

• Potentially higher electrical efficiency than other

CHP systems.

• Electrical efficiencies of 50% theoretically

possible

• Very low NOx

• Have to be brought up to temperature before

generation begins


Fuel Cells http://www.fueleconomy.gov/feg/fcv_pem.shtml

12


Phosphoric Acid Fuel Cell in Woking

• 200kWe

• Used to heat part of

district heating scheme

• Electrical Efficiency 37%

• Overall efficiency 85%

• Availability 90%

• Degradation of the fuel

cell has been observed


Phosphoric Acid Fuel Cell in London

• 200kWe

• 263kWth

• Used provide heat for

space heating and

cooling for Transport

for London

• High electrical

efficiency 36%

13


Conclusions

• CHP can give significant financial and CO2

savings.

• Sizing and system selection will be critical

• Maintenance has a significant impact on

operation


Micro CHP

14


Micro CHP – A Developing Technology

• Usually fuelled by gas

• Two major types of engines used:

• Reciprocating engines – electrical output typically

starts at 5kW with 10-12kW thermal output. -

Development continuing - market leader in the UK is

Baxi Dachs

• Stirling Engine – external combustion engine with a

sealed system using an inert working fluid, usually

helium or hydrogen. From 0.5kWe upwards – leading

brand WhisperGen – lower electrical efficiencies, but

quieter

• Micro fuel cell coming to market


MSR2 Controller

Exhaust heat

exchanger

Single cylinder

4-stroke engine Water cooled

asynchronous

generator

Main components of micro-CHP

720 mm 1070 mm

Gas inlet

Illustration courtesy of Baxi-SenerTec

15


Stirling Engine

• Working gas is heated

and cooled cyclically

• Exhaust heat used for

heating

• Theoretical high efficiency

but difficult to achieve.

• Seals require regular

replacement

Source Wikipedia


Principal Differences from Large Scale

• Uses an asynchronous generator so unsuitable

for standby generation

• Lower electrical efficiency due to scale

Source CTC 727 Micro CHP Accelerator

16


WisperGen

• 1 kW Stirling Engine micro CHP

• 46db at full power

• Field trials since 2004 – developed

in conjunction with E.ON UK –

report from E.ON in May 2006

states:

• Average CO2 savings for the

sample homes were 16% and up

to 19%

• Family homes, typical of target

market, save 1.1-1.5 tonnes of

CO2 p.a.

• Unit could pay for itself in 3 years


• Domestic, wall hung CHP unit

• Stirling engine, operates to

6kWth (1kWe)

• Supplementary heat exchanger,

operated to 18kWth

• Spool valve air control

• Preferred distributor British Gas

Flue outlet Supplementary

burner

Engine

Supplementary

Heat Exchanger

Engine burner

Electronic

control

Spool

Valve

Baxi Ecogen

C:/Documents and Settings/GibsonC/shawd/Baxi-SenerTec desktop files_3.9.08/lucask/My Documents/KLucas/Full res with compression.mov

17


Baxi Innotec PEM Fuel Cell –

Electrical power: 1.0 kWe net

Thermal power: ~ 1.7 kWth

Additional heat

generator: 15 kWth

Total efficiency: > 80%

Fuel pressure: 20-45 mbar

Grid connection: 230 Volt / 50 Hz

Dimensions: ~ 0.6 x 0.7 x 1.6 m

Noise: < 55 dB(A)

Modulates down to 30% of full load

Source Baxi


Micro CHP – Dachs • 20,000 systems worldwide

• 5.5 kWe depending on fuel

• 12.5 to 15.5 kWth heat

output

• Overall efficiency 79% to

92%

• Noise levels 52 dB(A) at 1m

• 80,000 hours design life

• Service interval 3500 hours

• Up to 10 DACHS can be

installed in a multi module

arrangement

• Integrated modem for off-

site monitoring and control

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Micro CHP Ener-G

3 Units:

• Miller cycle engine

• 3.8-10-25kWe

• 8.4-17.3-38.4kWth

Electrical efficiency

• 27.7-30.7-33.5%

• Overall efficiency 85%

• 10,000 hour service interval


Commercially Available (?) Systems

• For your home: WhisperGen

http://www.whispergen.com/main/contact/ &

Baxi Ecogen http://www.baxi.co.uk/ecogen

• For very large homes (with swimming pools),

small hotels, schools etc.:

Baxi-SenerTec UK (Dachs) (http://www.baxitech.co.uk/)

EC Power (www.ecpower.co.uk),

Ener-G (http://www.energ.co.uk/)

http://www.microchap.info/external_combustion_engines.htm

http://www.whispergen.com/main/contact/

http://www.baxi.co.uk/ecogen

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Costs

• Installed cost approx £5,500

(EST)

• Savings approx £150 p.a.

compared to a conventional

gas fired boiler (EST)

• £13,000 for 5.5kWe

(12.5kWth) plus flue,

installation and

commissioning


Carbon Trust Micro CHP accelerator report • Extensive field trial of domestic and small scale

CHP and condensing boiler units . Key findings

• Additional training of occupiers and installers

required

• Micro CHP show little benefit in modern well

insulated or smaller buildings with heat

demands of less than 20,000kWh

• Condensing boilers operate 4-5% lower than

SEDBUK rating

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Conclusion

• Micro schemes are technically possible

• The match between heating and electrical

demand is critical.

• Domestic applications can lack running hours

required to make projects economic.

• Probably suit small industrial/ commercial

projects better.


System Design

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Energy

• The ability to do work


Power

• The rate that we do use or produce energy.

22


Gross and Net Calorific Value

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

0 20 40 60 80 100 120

kJ

/kg

Moisture Content

Calorific Value of Wood

Net CV Wet Matter Basis Gross CV Wet Matter Basis


Calorific Values of Fuels

Fuel

Gross

Energy

Content

Net Energy

Content Units Comment

GAS 10.75 9.6 kWh/m3

OIL(35 sec) 10.74 10.08 kWh/litre Heating Oil

OIL(28 sec) 10.35 9.72 kWh/litre Kerosene

COAL 8.33 8.08 kWh/kg

ANTHRACITE 9.1 8.97 kWh/kg

LPG 7.14 kWh/litre

Wood Pellets 4.8 kWh/kg

Wood Chips 3.2 kWh/kg

@ 30%

moisture content

Wood Logs 3.8 kWh/kg

@20% moisture

content

23


Heating Systems

• A heating system needs to

• Deliver enough energy over a period of time to

meet the total demand, this is what you pay for

in your fuel bill

• Deliver the energy at a rate that is required to

maintain comfort level (power).

• The rate will be dependant on weather

conditions and the temperature at which the

comfort level is set


Heating Systems

• Loads vary

throughout the day

and the year.

• The base load is the

minimum demand

• Peak load is the

maximum demand Base Load

Peak load

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Months Winter Summer

1 2 3 4 5 6 7 8 9 10 11 12

50%

100%

Heat demand

Heating

Heating

Base load - e.g.. hot water, swimming pool

Winter

Heating Systems


Heating System Loads

Base Load

Peak Load

25


System Design

To achieve CO2 saving, economic viability and CHPQA we

need to ensure:

• Electrical efficiency over 20%

• Most of the heat that the plant produces is consumed

• Low gas price

• High electricity price

• Minimise electricity export as value is usually lower


System Design

To achieve this

• Maximise heat load

• Smooth heat load on CHP to remove peaks

• Size plant to meet base loads

• Design for a minimum of 5000 operating hours

p.a.

26


System Design

• Electrically led 300kWe

Heat demand and CHP supply Electrical demand and supply

Waste Heat


System Design

• Heat led

Heat demand and CHP supply Electrical demand and supply

27


System Design

• CHP can be sized to meet heat demand

• Use demand side management to smooth load

• i.e. heat Service Hot Water off peak heating

demand include buffer storage

• Increase the heat load by connecting more than

one building

• Increase diversity by connecting to more than

one type of user


Systems Connections

• CHP should be lead boiler

• Ideally into common header with other boilers

• But can be in series with higher losses

Source GPG388

28


District Energy (Heating)

• District Energy is the

piping of heat (&

potentially cooling) to a

number of buildings from

a CHP generation plant or

central boiler

• Heat losses 1°C per km


District heating Steel or Pex pipe? PEX

• Easier to lay goes around bends

• Can be compression or thermally

joined

• Operational life up to 50 years

depending on pressure

Steel

• Available in larger sizes

• More robust but suffers from

corrosion

• Steel higher installed cost

• Both can be fitted with leak

detection systems

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District Heating losses Consider a load of 100kW at a distance of

200m

• Head loss needs to be no more than 1

bar (10kpa) or 200pa/m

• Assuming 30oC drop flow -return

• Then 50/48 DN 40 pipe required

• Assuming an average operating

temperature of 70oC heat loss is

11.2W/m or 400x 11.2=4.48kW

(<5%)

• If system runs at a capacity factor of

25% then heat delivered in year

=100*8760*0.25/1000=245MWh

• Loss =4.48*8760/1000=39MWh

=16%


Heat Losses Conclusions

• Modern housing with its low heating loads will have a very

low capacity factor making losses more significant

• Summer Service hot water loads will present the operator

with very high losses, consider alternative means of

provision

• Design system to run at high temperature drop,

encourage LT emitters

• Try to have different types of load spread through the

network

• Solution is to turn the network off during low load periods

• Could be achieved with local heat sources and storage

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Electrical Connection

• Must comply with ER G59/2

• Or G3/1 below 16A/phase

• Defines voltage and frequency limits

• Requires detection and disconnection during loss of mains

• Contact DNO to discuss requirements

G59 relay

Source GPG60


Design tools

• CHP Sizer from

http://chp.defra.gov.uk/c

ms/tools

• Termis/ Heat map

network design tool

• Energy pro

http://chp.defra.gov.uk/cms/tools

http://chp.defra.gov.uk/cms/tools

31


Design Conclusions

• Systems need to be heat led

• Either meeting base load or high percentile load

• Careful modelling required to accurately predict

performance

• Mixed load profiles help smooth load

• Modern housing presents potential challenges


Heat Reclaim Tri-generation CHP

32


Covered during this session

• Heat reclaim

• Trigeneration

• Conclusions


Heat reclaim

• Some sites have significant amounts of waste

heat which could potentially used to generate

electricity.

• E.g. refineries ,ovens, paper mills.

• If the waste heat is at temperatures in excess of

approximately 400oC there may be an

opportunity for CHP.

• There are a number of potentially suitable

technologies.

33


Combustion - Rankine (steam) cycle

Heat Circuit

Power Output

ORC Unit


Rankine cycle properties

Typical Size Input temperature Electrical

Efficiency

Modulation O&M

Rankine Cycle Steam -2MWe+ 400-600 20-30% Yes High pressure

steam requires

continuous

staff

ORC – 0.05-

2.2MWe

80-400 10-20% Yes

• Performance related to input and output temperature drop

• An ORC with an input temperature of 80oC will need a

condenser at a lower temperature and have a poor efficiency

• If there is a requirement to reclaim some heat for a process

such as space heating this may reduce the potential

temperature drop and hence efficiency

34


Combustion - Hot air turbine

Flue Gas

Hot Air Turbine

Cold air inlet Hot air exhaust

Compressor stage Turbine Stage

Generator

Air to air heat exchanger Thermal

Output

Power Output

Heat Exchanger


Hot air turbine properties

Expensive for output – waste wood use most economic fuel.

High input temperature makes it an unlikely candidate for heat reclaim

Typical Size Input

temperature

Electrical

Efficiency

Modulation Maintenance

Hot air

turbine

0.1 MWe 800 1015% Yes but

limited

Higher

35


Combustion - Stirling engine

35 kWe

1.5 -3 kWe


Stirling Engine properties

Few commercial suppliers

High input temperature to achieve reasonable efficiency

Typical Size Input

temperature

Electrical

Efficiency

Modulation Maintenance

Stirling

Engine

0.0.35-100 kWe 600 10-20% Yes Seals can be

an issue

36


Heat Reclaim Considerations

• If temperatures and scale are high enough then heat

reclaim to electricity is possible.

• ORC is probably the best candidate unless scale is very

large.

• Long operating hours will be required to achieve financial

return.

• Ensure that there is sufficient electrical load to absorb the

resulting generation

• Great care is required to ensure the existing process is not

affected e.g. cooling flue gasses will reduce buoyancy and

draught of a chimney


Alternative Fuels - Standard engines

37


Standard engines

Typical

Size

Heat to

Power

Ratio

Electrical

Efficiency

Modul

ation

Fuel

Quality

Maintenance NOx

Standard

engines

0.05-2 MWe 2.5-3 : 1 25-30% Yes Intolerant Higher Higher

Fuels can be vegetable oil derived fuels for diesel engines,

bio-ethanol and biogas from anaerobic digestion for spark

ignition engines

Relatively low capital cost – simple process

Relatively high fuel cost (liquid biofuels)

Small foot print and store size – liquid fuels are very energy dense – fewer vehicle movements

Fuel quality must be assured or operational problems will result


Bio oils

• Sources such as

• Rape, sunflowers, jatrophia, palm oil

• Can be used directly in converted diesel

engines

• Or transesterified to create biodiesels

38


Seed Oils – General Considerations

• Can be used unrefined, transesterified into Fatty Acid

Methyl Esters – FAME, also referred to as Rape Methyl

Ester- RME commonly termed biodiesel

• New or used oil can be transesterified

• Have high viscosity in ‘raw’ form due to the presence of

glycerol/glycerine compared to fossil fuels

• Transesterification reduces viscosity by removing

glycerine

• Oxygen is present on the molecules of both triglycerides

and FAME giving good combustion

• Glycerine has toxic HT breakdown products and tends to

polymerise with heat


Transesterification

200ml Methyl Alcohol

3.5grams Sodium Hydroxide

1000ml of rape seed oil

Glycerine

Biodiesel

39


Seed Oils – General Considerations cont’

• Glycerine has toxic HT breakdown products and tends to

polymerise with heat

• Biodiesel can be used in ‘unconverted’ diesel engines,

heating plant and gas turbines but the oxygen is

corrosive so fuel lines/containers must be resistant. Has

a calorific value of 37 MJ/kg

• ‘Straight’ vegetable oil can be used in converted

engines, either two tank or Elsbett conversions, can be

used in converted heating plant with emulsifying

atomisers, cannot be used in gas turbines? Used oil is

not suitable due to presence of salt. Calorific value of

rapeseed oil 39 MJ/kg


Bio Oils

• Bio-Oils can be used to drive IC engines .

• Maintenance load on engine will be much

greater than when using NG.

• Will compete with road fuel as an end use.

• The sustainability of using bio oils needs careful

consideration before investment is made.

40


Trigeneration (CCHP) Absorption/adsorption chillers use heat from hot water to produce chilled water

Most common technology is the Lithium Bromide absorption chiller

Efficiency is around 50% - 120% efficiency is improved at higher hot water supply temps (minimum is 85ºC)

Produce chilled water at around 6ºC (returning at around 12 ºC)

Can be used to cool buildings with a chilled water circuit

1 MW absorption chiller


Coolth Generators

• Absorption chillers

use heat as the

driving force. Can be

used with a wide

range of heat

sources

41


Single and Double Effect Chillers

Single Effect

• Low input temperature

90-130oC

• CoP 0.6-0.8

• 70kW-5MW

Double Effect

• Higher input

temperature 180oC

• CoP 1.0-1.4

• 223kW

• High capital and maintenance costs require log

running hours for payback

• Large amounts of low grade heat have to be

ejected


Teufelburger Wells Austria

• Tri-generation plant

for plastic factor

• 4.2MW biomass boiler

• 0.5MW ORC

• 2.35 MW single stage

chiller

42


Pfaffenhofen Bavaria

http://www.eta-energieberatung.de/biomasse-e/M_wk/wk.html

80,000 t of fuel

Saves 65,000t of CO2

7.5 MVA Steam Turbine

26.7MWt

€41million

District Heating and Cooling


Conclusions

• The most reliable/least risk approach (Rankine) is suited

to high energy use developments.

• Careful consideration of load and process required to

ensure a successful conclusion.

43


CHP Cost, Maintenance, Policy & Quality Assurance


CHP Capital Costs

• Typically around £1000/kWe

Source GPG 388 2004, CT 2008 , DECC 2011

44


Maintenance for IC Engine Dailey Checks

Daily

• Performance monitoring Check

• Visual Inspection


Maintenance-Monthly -500-700hours • Check fluid levels

• Check running records for plant performance trends

• Check starter battery condition

• Change oil filter and gas inlet filter

• Send oil sample for analysis

• Check cylinder compression

• Adjust-valve clearance-spark plug gap-ignition timing

• Clean distributor cap

• Check exhaust back pressure and emissions

• Check gas pressure .adjust gas/air ratio

• Check auxiliary equipment pumps etc.

45


Maintenance Bi-monthly –1000-1500hours

• Change oil (sooner if fuelled with diesel)

• Check and renew spark plugs

• Check and reset valve clearances

• Renew air filter

• Examine alternator air intake filter

• Check condition and tension of belts

• Check starter motor operation

• Check operation of monitoring system


Maintenance six monthly or 4000hours

• Check condition and performance of engine

enclosure ventilation system

• Check condition of alternator pumps and fan

bearing condition monitoring

• Inspect heat dump radiator

46


Maintenance Four Annual or 30,000hours

• Inspect ,overhaul and replace engine major

mechanical parts: cylinder heads, valves,

pistons, cylinder liners

• Inspect auxiliary pumps fans and equipment

overhaul if required

• Inspect alternator bearings

• Dismantle and thoroughly clean alternator


Maintenance Cost

• Increases for smaller units

Source GPG 388 2004

47


CHP Policy

• A new EC directive to promote CHP and district

heating as the default position for new

developments. Locating developments near to

sources of waste heat. Source http://www.chpa.co.uk/efficiency-directive-

to-capture-waste-heat-opportunity_585.html

• The UK government has published heat load

maps of the UK.


Good Quality CHP

• CHPQA (quality assurance scheme) aims to

promote ‘good quality CHP’

• The methodology determines how much heat

should be used – larger schemes require less heat

to be used

• See

https://www.chpqa.com/guidance_notes/document

s/CHPQA_Standard_Issue3.pdf for the latest (Jan

2009) guidance on the scheme

• Necessary if LEC financial benefits are to be claimed

http://www.chpa.co.uk/efficiency-directive-to-capture-waste-heat-opportunity_585.html













https://www.chpqa.com/guidance_notes/documents/CHPQA_Standard_Issue3.pdf

https://www.chpqa.com/guidance_notes/documents/CHPQA_Standard_Issue3.pdf

48


CHP QA Residential

• Has special arrangements for residential user

• Referred to as Residential Community Heating

• Can be based over heating season or annually

• Heating season is defined by user


CHPQA One of the following has to be met:

• The proportion of CHP Qualifying Heat Output (CHPQHO) in Annual

Operation provided for Residential Use is >60%.

• The proportion of CHP Qualifying Heat Output (CHPQHO) during the

Heating Season provided for Residential Use is >70%.

• The proportion of CHP Qualifying Heat Output (CHPQHO) at MaxHeat

provided for Residential Use is >60%.

• Residential Users out-number institutional, commercial and

industrial customers by at least 50:1 and the proportion of CHPQHO

in Annual Operation supplied for Residential Use is ≥10%.

• In the case of proposed, new Schemes, Schemes in Initial Operation

and Schemes that are developing as defined in the CHPQA Guidance

Notes, the proportion of CHPQHC for Residential Use is >60%.

49


CHPQA Max heat output

Must be maintained for at least

• Industrial, commercial or institutional 1000

hours (<10% CHPQHO to Residential Users)

• Mixed residential, institutional, commercial or

industrial 750 hours (≥10% residential)

• Residential Community Heating 500 hours


CHP QA

• Small scale scheme<2MW

• Initial Period has lower threshold criteria

• Project must meet quality index targets

• A Scheme that qualifies as Good Quality CHP for its entire

annual energy inputs is one where the Power Efficiency

equals or exceeds 20%.

Operating Regime QI>

1 Entire annual energy or agreed output period 100

2 Initial operation of 1 95

3 At its Maximum Heat Output under Normal Operating Conditions.

100

4 New schemes at design, specification, tendering and approvals stages,

105

50


CHPQA QI

• QI = (X x ηpower) + (Y x ηheat) where

• ηpower= electrical efficiency

• ηheat = thermal efficiency

• ηpower = CHPTPO/CHPTFI

• ηheat = CHPQHO/CHPTFI


CHPQA QI

• Table applies

from 2010

• Lots of fine print

to get right

Size Of Scheme

(CHPTPC)

QI Definition

CONVENTIONAL FOSSIL FUELS SCHEMES

Natural gas (inc. Reciprocating Engines)

≤1MWe QI = 249 x ηpower + 115 x ηheat

>1 to ≤10MWe QI = 195 x ηpower + 115 x ηheat

Oil


SPECIAL CASES

FUEL CELL SCHEMES QI = 180 x ηpower + 120 x ηheat

ALTERNATIVE FUEL SCHEMES3

By-Product Gases



>25MWe QI = 193 x ηpower + 120 x ηheat

Biogas

<=1MWe QI = 285 x ηpower + 120 x ηheat


Waste Gas or Heat



Liquid Biofuels



Liquid Waste



Biomass or Solid Waste



Wood Fuels



51


Financial Incentives

• Schemes that are Good Quality are awarded financial

benefits:

• Enhanced Capital Allowances (ECAs) on approved plant

capital costs allowing 100% right off in first year

• Levy Exemption Certificates on electrical output sold to

LEC commercial clients whether on or off site (all fuels)

(£4.85/MWh)

• Micro (below 2kW) receive a feed in tariff of 10.5p/kWh

• Product and installer must be MCS certified

• Total numbers limited to 30,000


Financial Incentives

• Plant fuelled by bio-liquids and waste can claim

Renewable Obligation Certificates (ROC)

• CHP from waste plants which haven’t registered

for ROC will be able to claim the Renewable

Heat Incentive (RHI).

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Regulation

• Local Authority Air Quality Control permit system

0.4MWt-3MWt

• IPPC – Environment Agency permits systems > 3MWt

• Distribution Network Operator (DNO) involvement

required for grid connection

• Ofgem rules require private electricity users are given

the right to terminate power supply contracts with 28

days notice

• Ofgem generators license required for power outputs

over 5MW

• Planning for plant house inc noise assessment


Barriers to Take Up

• Retrofitting difficult due to high capital costs and the

complexity of projects.

• A suitable heat load is needed, which means dense energy

usage and mixed load curves.

• Invasive and expensive to install the heat networks and

customers are not guaranteed to connect even when you

do.

• A lack of understanding of the technology and its potential

has caused many opportunities to be missed.

• More widespread in Norway, Denmark, the Netherlands,

Germany and Finland.

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Conclusion.

• CHP QA is critical to claiming most benefits.

• Small domestic projects can claim FIT.

• Great care is required to ensure eligibility

• All projects require a significant reporting

regime


Case Studies

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Southampton District Energy Scheme


& from the Outside

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Birmingham District Energy Company


Central Milton Keynes

• CHP plant room housing a 3MW Jenbacher gas engine (a second

3MW engine to be added).

• 17MW gas boiler.

• Three thermal stores and flue.

• District heating main and power cables.

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Industrial Uses

• Gas CHP plant at Immingham

supplies up to 734 MWe to the

grid plus steam (used for oil

refining).

• 2.5MWe biomass CHP plant at

Balcas Timber in Enniskillen –

fuelled by wood pellets

manufactured by the company.

• Scottish & Newcastle Brewery is

installing a 4.7MW biomass

(partly spent grain) CHP plant

in Manchester.


Conclusions

• There is a CHP unit suitable for every scale of

development

• To ensure most beneficial carbon and cost savings, the

CHP unit needs to be working at maximum output with

minimal cycling on and off

• Sites with dense energy usage and mixed loads work best

• Micro CHP systems offer good carbon savings if correctly

sized,

• No grants available for gas fired CHP

http://www.modernpowersystems.com/graphic.asp?sc=2027061&seq=8

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Thank you for your attention?

Rob Gwillim

[email protected]

Sandra Hayes

[email protected]