Gemini Center Energy and Climatization Energy and Environment (1) Professor Vojislav Novakovic, PhD Department for Energy and Process Engineering Norwegian

Gemini Center Energy and Climatization

Energy and Environment(1)

Professor Vojislav Novakovic, PhD

Department for Energy and Process EngineeringNorwegian University of Science and Technology

PhD Program “Sustainable Energy and Environment in Western Balkans”

Third joint seminar: Energy and Environment

Faculty of Mechanical Engineering, East Sarajevo, Bosnia and Herzegovina, 21-24 May 2007


Energy and EnvironmentOutline

World energy challenge Demands for energy Forms of energy

Quality of energy Energy conversion Coefficients of efficiency

Holistic approach to energy efficiency in buildings


Challenges the World Is Facing Today

To secure enough Food and Energy

For rapidly increasing population Reduce the environmental impact


Demand for Energy = Demand for Energy Services

Energy covers our requirements

Basic needs

Preparation of food

Heating Personal hygiene Light Work

Needs of the industrial society

Production Transportation

Goods Commodities


Losses

Energy Use and Its Impact on the Environment

Sources of energy

Sun Water Oil Gas Coal Nuclear Bio Wind Ocean

Energy services

Heating

Cooling

Work

Light

Emissions of

CO2, NOx, SO2,...



Heat Balance for the Earth (TW)Solar irradiation

is more than 10.000 times larger

than the energyutilized by people

on the Earth

Photosynthesis utilize

10 times more energy

than people on the Earth use

Moon andplanet

motion

Plants

Fossil fuel Uranium Geothermalheat

Reflectedsolar radiation

53.000

Heatradiation

83.000

41.000

Rivers 5

3

Tide

Wind, waves, ocean streams 370

100Photosynthesis Degradation 35

Heat losNuclear power

0,5Exploitation

sensible heat in air, waterand earth

Ice, watermoisture

CondensationFreezing

EvaporationMelting

7,5

Solar radiation178.000


Forms of Energy

Potential Kinetic Mechanical

Electric Heat

Internal Chemical Nuclear

Electromagnetic radiation


Renewable Energy Resources

Solar radiation Hydro Wind Ocean related energy

Wave, tidal, thermal gradient, salinity gradient

Chemical energy Crops, wood, forest residues, waste

Geothermal Internal


Non-Renewable Energy Resources

Chemical energy Fossil fuels

coal, oil, gas, peat, tarf, oil shale, marlstone, tar sand

Nuclear energy Uranium


RelationResources - Reserves

When resources are: Exactly proven and Exploitation is profitable

Resources become reserves

Reserves

Proven Not discovered

Profitable

Not profitable Resources


The Basic Laws of Thermodynamics

The First Law of Thermodynamics

Law of energy conservation

Energy and materials are always conserved

They can be neither created or destroyed

Only converted from one state or form to another


Conversion of Energy

Heat production

Solar Geothermal Combustion Electricity Heat pumps Nuclear

Electricity production

Solar Hydro Wind Wave Tidewater Geothermal Combustion Nuclear Fission


Conversion of Energy Electricity Production

Heat power plants

Solar energy Photosynthesis Carbonization Combustion Heat Mechanical work Electricity

Hydro power plants

Solar energy Evaporation Condensation Elevation Motion Mechanical work Electricity


Water Cycle in the Nature


Hydro Power Station

Headwaterlevel

Turbine

Water tunnel

Generator

Tailwaterlevel



The Second Law of Thermodynamics

Law of energy quality

Explain to which extent the conversion from one form of energy to an other is possible

Quality of energy – there are three grades of energy quality

Mechanical energy is the energy form with higher quality than heat energy


Quality of Energy

Maximum Achievable Amount of Mechanical Work

EQ = -----------------------------------Supplied Energy

Wmax

EQ = -------- Q


Three Grades of Energy

Energy of 1.Grade

might be converted to any other form of energy without any limitations

Mechanical: work, potential, kinetic, pressure Electrical: electromagnetic (sun), electrostatic Chemical: fuels Nuclear: fission, fusion

Pure Exergy



Energy of 2.Grade

might be converted to other forms of energy but only to a limited extent

Thermal: heat Internal: temperature, state change

Mixture of Exergy and Anergi



Energy of 3.Grade

can not be converted to any other form of energy

Internal energy in surroundings

Pure Anergi



1.Law Energy = Exergy + Anergi

2.Law Portions of either Exergy or Anergi might be equal

to zero

Exergy high quality energy which could be converted to

useful work Anergi

low quality energy which is not possible to convert to exergy


Quality of Thermal Energy

Exergy

Anergi

Energy0

50

100

150

200

250

300

350

400

Entropy, S [kJ /K]

Tem

peratu

re,

T [

K] Tr – The

temperature at which the heat is delivered

To – The temperature of the surroundings


Quality of Energy for Heat Source

Wmax Tsource- Tsurroundings

EQ = ------- = ---------------- Q Tsource

Absolute temperature

T [K] = t [C] + 273,16


Quality of Energy for Heat Source

Temperature of the heat source [C]

Quality of Energy

2000 0,880

1500 0,856

1000 0,786

500 0,646

250 0,478

100 0,268

50 0,155

20 0,068

0 0,000


Example: Gas fired power plant

Combustion products 1500 - 2000 C EK = 0,88

Limitation of material 1200 - 1300 C EK = 0,60

Energy loss in cooling water t = 20 C EK = 0,10


Quality of Energy for Heat Supply

What temperature demand do we have for the heat that is supplied

Tneed

Wmin Tneed - Tsurroundings

EQ = ------- = --------------- Q Tneed


Quality of Energy for Heat Supply

Temperature demand [C] Quality of Energy

1000 0,786

500 0,646

250 0,478

100 0,268

80 0,227

60 0,180

40 0,128

20 0,068

0 0,000


Quality of Energy for Space Heating

Energy: Q = Exergy + Anergi = 100%

Exergy: E = Q (Tr-To) / Tr

E = 100% (295-273)/295 = 7,5%

Anergi: B = Q To / Tr

E = 100% 273/295 = 92,5%


Utilization of Energy

Efficiency of energy utilization

Useful energy versus energy input Coefficient of efficiency Commercial coefficient

Useful energy versus theoretically achievable Coefficient of performance Environmental coefficient


Coefficient of Efficiency

Useful energy Qin-Qloss

= --------------- = ---------

Energy input Qin

tot = a b c d ...


Coefficient of Efficiency for Hydro Power Production in Norway

All figures are in TWh

Storage = 120 / 131 = 0,92

Production = 104 / 120 = 0,87

Distribution = 95 / 104 = 0,91

Total = 0,920,870,91= 0,72


Coefficients of Efficiency for Energy Conversion

Wood-burning stove 75 %

Kerosene stove 80 %

Central domestic heating 80 %

Thermal power plant (coal) 45 %

Thermal power plant (gas) 52 %

Hydro-electric power station 87 %

Electricity generator 98 %

Photovoltaic cell 16 %


Why Do We Build Buildings ?

To protect our selves and our private property against: The external climate – rain, snow, wind, sun etc Disturbances from other peoples

To create good and safe conditions for all our indoor activities in: Houses:

Preparing food, eating, catering for personal hygiene requirements, sleeping, doing hobbies, etc

Commercial, industrial or service buildings: Working, or receiving various types of services


Net End Use of Energy inOnshore Norway in 2005: 225 TWh

Energy sourcesTransportation

Industry

Buildings


Demands That We Place on Our Buildings

To provide a healthy and comfortable indoor environment

To be economical regarding investments and operational expenses

To be reliable and safe without negative impacts on the outdoor environment


Energy Efficiency in Buildings

Outdoor environment

Building envelope

Technical installations

Building owners and users

Outdoor temperature

Basic designEnergy supply/transformation

BehaviorHabits

Solar radiationThermal

insulationHeating/Cooling

VentilationActivity

Working hours

Wind Air tightnessAir handling

Heat recoverySundry gains

Moisture Heat capacityLighting

Automatic controls

Operation Maintenance

Surroundings FenestrationDom.hot water

SanitaryManagementDevelopment

ENERGY CONSUMPTION - INDOOR ENVIRONMENT COSTS OF OPERATION


Energy and EnvironmentSummary

World energy challenge Demands for energy Forms of energy

Quality of energy Energy conversion Coefficients of efficiency

Holistic approach to energy efficiency in buildings


Energy and Environment

*The End

*Fin*

Konec*

Slutt*

Kraj*

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Gemini Center Energy and Climatization Energy and Environment (1) Professor Vojislav Novakovic, PhD Department for Energy and Process Engineering Norwegian