Kurnitski Clima2010 plenary


Published on

Jarek Kurnitski's presentation at 10th anniversary REHVA seminar Clima2010 in Antalya, Turkey on 9-12 May 2010
Accounting CO2 emissions for electricity and district heat

  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Kurnitski Clima2010 plenary

  1. 1. Accounting CO2 emissions forelectricity and district heat usedin buildings – a scientific methodto define energy carrier factors Jarek Kurnitski Senior Lead, Built Environment Sitra, the Finnish Innovation Fund Adjunct Professor, Aalto University 11.5.2010 CLIMA 2010
  2. 2. Assessment of emissions caused by energy used inbuildings• Buildings use energy measured or calculated in kWh-s• The use of 1 kWh energy can cause very different emissions or primary energy use, depending on production sources• This is usually taken into account with energy carrier factors in energy performance regulationTwo main purposes of this assessment:• Estimate actual CO2-emissions or primary energy use caused by energy production – can be calculated from energy statistics• Regulative purpose, derivation of energy carrier factors used in energy performance requirements of building codes• Regulation has to take into account demand and capacity changes in the market and direct construction according to energy policy Jarek Kurnitski 11.5.2010 © Sitra 2010
  3. 3. EN 15603 – General framework for the assessment ofenergy performance (EP) of buildings • EP-rating sums up all delivered energy (electricity, district heat/cooling, fuels) into a single rating with relevant weighting factors (EN 15603) • Relevant weighting factors for energy sources (energy carriers) are the key issue for accountable energy performance requirements Delivered energy Building A Building B Electricity, kWh/(m2 a) 100 50 District heat, kWh/(m2 a) 50 100 Total, kWh/(m2 a) 150 150 • With weighting factors based on CO2 emissions (example): Delivered energy Building A Building B Electricity, kWh/(m2 a) 100*2 50*2 District heat, kWh/(m2 a) 50*0.8 100*0.8 Total, kWh/(m2 a) 240 180 EP ≤ 200 Jarek Kurnitski 11.5.2010 © Sitra 2010
  4. 4. Energy ratings • EN 15603: calculation of energy ratings in terms of primary energy, CO2 emissions or parameters defined by national energy policy Other services cause often confusion as they are not included in the rating in all countries • Based on net delivered energy (by all energy carriers), weighted energy rating (primary energy or CO2 emission) is calculated (used in majority of member states) Jarek Kurnitski 11.5.2010 © Sitra 2010
  5. 5. Calculation of CO2 emissions and primary energyEmissions [kgCO2] =energy flow [MWh] x specific emission factor [kgCO2/MWh]Primary energy = energy flow [MWh] x primary energy factor [-]Weighted energy rating = energy flow [MWh] x energy carrier factor [-]• Example house with 18 MWh natural gas and 7 MWh electricity use: 18 MWh * 200 kgCO2/MWh = 3600 kgCO2 = 3,6 tCO2 (natural gas) 7 MWh * 300 kgCO2/MWh = 2100 kgCO2 = 2,1 tCO2 (electricity) in total 5,7 tCO2 per year• Alternatively this calculation can be done with relative energy carrier factors defined in relation to some reference (gas), i.e. 1.0 for gas and 1.5 for electricity, to use kWh-units Jarek Kurnitski 11.5.2010 © Sitra 2010
  6. 6. Primary energy• Primary energy use refers to the use of natural resources1• Primary energy factor for fossil fuels is 1.0 if extraction, refinery, transport etc. are not taken into account• 1/0.4=2.5 for electricity generated from fossil fuel with efficiency of 40%• Usually, only non-renewable primary energy is considered (i.e. the factor is close to zero for hydropower, wind, solar)• Nuclear energy is difficult to treat within primary energy concept: - Primary energy factor depends on the selection, which energy (thermal or electrical) is used as the primary energy form - Thermal efficiency of 33% leads to primary energy factor of 3.0 (IEA, Eurostat) and if electricity is used as the first energy form, primary energy factor will be 1.0 (UNSD)1Definition (for a building): Non-renewable primary energy is the non-renewable energy used toproduced the energy delivered to the building. It is calculated from delivered energy amounts of energycarriers, using conversion factors (EN 15603:2008). Jarek Kurnitski 11.5.2010 © Sitra 2010
  7. 7. Primary Energy Factors of Electricity Generation in Europe in 2006 source: Eurostat 2009 (Eurostat primary energy conventions), non-renewable only Norway 0,0 Austria 0,7Finland, Sweden, Norway 1,0 Switzerland 1,3 Luxemburg 1,4 Sweden 1,5 Portugal 1,5 Latvia 1,5 Italy 1,7 Denmark 1,9 Spain 1,9 Ireland 1,9 Finland 2,0 Netherlands 2,1 United Kingdom 2,2 EU-27 2,2 Germany 2,3 Slovenia 2,4 Romania 2,5 Slovakia 2,5 Belgium 2,5 France 2,6 Greece 2,7 Hungary 2,7 Cyprus 2,8 Estonia 2,8 Poland 2,8 Lithuania 2,9 Bulgaria 3,0 Czech Republic 3,0 Malta 3,4 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 Jarek Kurnitski 11.5.2010 4,0 primary energy factor MWh primary/MWhgross_electricity © Sitra 2010
  8. 8. Specific CO2-emissions of Electricity Generation in Europe in 2006 sources: Eurostat 2009 (IPCC default emission factors) Norway 3 Switzerland 6 Sweden 27 France 81Finland, Sweden, Norway 88 Lithuania 182 Austria 206 Belgium 228 Slovakia 283 Luxemburg 292 Latvia 324 Finland 352 Spain 388 Portugal 417 EU-27 436 Italy 448 Hungary 456 Slovenia 463 United Kingdom 498 Ireland 502 Netherlands 519 Germany 571 Denmark 601 Romania 714 Bulgaria 747 Cyprus 771 Czech Republic 816 Malta 941 Greece 943 Poland 1 051 Estonia 1 163 0 200 400 600 800 1000 1200 Jarek Kurnitski 11.5.2010 1400 specific CO2-emissions kg(CO2)/MWhnet © Sitra 2010
  9. 9. CO2-emissions vs. primary energy concept• Assessment of emissions vs. use of energy sources (primary energy)• Nuclear energy causes the major difference, as the primary energy factor depends on the definition by factor 3• For other energy carriers, weighting factors are very similar independently of the use of primary energy or CO2 approach (if calculated as relative to some reference, e.g. oil)• ⇒ somewhat higher weighting factor for electricity if primary energy approach is used• Use of CO2 emissions makes it more complicated to determine weighting factors for mix of many production sources, as shown in the following Jarek Kurnitski 11.5.2010 © Sitra 2010
  10. 10. Variation of primary energy factorsFour possible definitions:A. total primary energy and nuclear energy with 33% efficiency (IEA & Eurostat definition)B. non-renewable primary energy and nuclear energy with 33% efficiency (IEA & Eurostat definition)C. total primary energy and nuclear energy with 100% efficiency (UNSD definition)D. non-renewable primary energy and nuclear energy with 100% efficiency (UNSD definition) Jarek Kurnitski 11.5.2010 © Sitra 2010
  11. 11. Primary energy factors for electricity generation inFinland, definitions A to D Jarek Kurnitski 11.5.2010 © Sitra 2010
  12. 12. Primary energy factors for district heat in Finland,definitions A to D Jarek Kurnitski 11.5.2010 © Sitra 2010
  13. 13. Non-renewable primary energy factors (definition B) inFinland (blue electricity and red district heat) Jarek Kurnitski 11.5.2010 © Sitra 2010
  14. 14. Why primary energy factors are almost constant inthe long run?• Major changes in Finnish energy production until 2030: - Significantly increased share of nuclear energy - CHP is used as much as today, almost constant district heat production - Increased use of renewables (wind, bio, solar), as much as technically feasible, but still less dominating than nuclear or CHP• With IEA and Eurostat definition, primary energy equivalent of nuclear and conventional condensing power very similar, so, the compensating of condensing power will even slightly increase primary energy factor (40% vs. 33% efficiency)• ⇒ cutting emissions with nuclear energy has no effect on primary energy factor… Jarek Kurnitski 11.5.2010 © Sitra 2010
  15. 15. Regulatory aspectsEnergy performance regulation:• Controlling and directing the demand change• How much and which energy is used in buildings• Straightforward for new buildings, more complicated for existing• Regulation is often not directly linked to policies for energy production, however the both are important: - Regulation generates demand change in the existing market with consequences for developments in the production side - Obviously to be fitted together so that emissions can be reduced most efficiently• Buildings account for 41% of primary energy use in EU (Eurostat) being the largest single potential for energy savings Jarek Kurnitski 11.5.2010 © Sitra 2010
  16. 16. Finnish case study to determine emission basedenergy carrier factors including demand-capacitycoupling effects• CO2-emissions from electricity generation and district heat production: - Hourly data of specific emissions from 2000-2007 - Demand change analyses for electricity use - Demand change analyses for district heating use - Coupling with new capacity – scenarios - Derivation of energy carrier weighting factors based on energy system scenario calculations to show how much one energy carrier is causing more emissions than another Jarek Kurnitski 11.5.2010 © Sitra 2010
  17. 17. Electricity generation in Finland Electricity generation in Finland 2007 (GWh), in total 78 TWh (Statistics Finland) Industrial CHP CHP electricity electricity 15330 11430 Electricity generation, 20 % 15 % average specific 439 220 emission 2000-2007: kg(CO2)/MWh kg(CO2)/MWh 273 kg(CO2)/MWh Hydro power Separate 0 kg(CO2)/MWh 13991 District heat production, conventional 894 18 % average specific kg(CO2)/MWh thermal power emission 2000-2007: 14377 217 kg(CO2)/MWh 18 % Wind power 0 kg(CO2)/MWh 188 0% Nuclear energy 22501 29 % Jarek Kurnitski 11.5.2010 © Sitra 2010
  18. 18. Emissions of heat and power production (calculated with benefit allocation method) • Electricity generation in Finland 2007: 78 TWh • District heat and industrial steam production 2007: 95 TWhTotal emissions of electricity generation 2007 (milj.t CO2), Total emissions of electricity and district heat production 2007 (milj.t CO2), in total 21.7 milj.t CO2 in total 34.9 milj.t CO2 (Statistics Finland) (Statistics Finland) CHP electricity 6.7 Total production of 31 % industrial steam 5.9 17 % Industrial CHP electricity 2.2 Total production of Total generation of 10 % district heat conventional thermal 7.3 power Separate conventional 21 % 21.7 thermal power 62 % 12.8 59 % Jarek Kurnitski 11.5.2010 © Sitra 2010
  19. 19. Specific CO2 emissions of total electricity generation asa function of conventional thermal power 2006–2008 450 400 Specific CO2 emissions, kg(CO2)/MWh 350 300 250 200 150 100 50 0 0 500 1000 1500 2000 2500 3000 3500 4000 Separate conventional thermal power, MWe Kurnitski Jarek 11.5.2010 © Sitra 2010 Specific emissions calculated with benefit allocation method (Energy Statistics Finland 2008)
  20. 20. Just use average specific emission factors?• Average specific CO2-emissions 2000-2007: - 273 kg(CO2)/MWh) for electricity - 217 kg(CO2)/MWh) for district heat• Or average relative energy carrier factors (previous ones divided by reference specific emission of oil 267 kg(CO2)/MWh)): - 1.0 for electricity - 0.8 for district heat - (reference: 1.0 for oil)• These average factors would probably lead to increased use of electricity in buildings (electrical heating etc.) as 1.0 is very low compared to common primary energy factor of 2.5 for electricity• What was not taken into account? Jarek Kurnitski 11.5.2010 © Sitra 2010
  21. 21. Higher factor for electricity in winter?• Hypotheses: peak loads cause higher specific emissions in the production• Can be easily tested with hourly data Jarek Kurnitski 11.5.2010 © Sitra 2010
  22. 22. Specific CO2 emissions of total electricity generationas a function of outdoor temperature 2006–2008 450 Specific CO2 emissions, kg(CO2)/MWh 400 350 300 250 200 150 100 50 0 -26 -22 -18 -14 -10 -6 -2 2 6 10 14 18 22 26 30 Outdoor temperature at Helsinki, °C • Generation of separate conventional thermal power in Finland can be high in summer period due to shortage of hydro power and lack of CHP which is generated against heat load of district heating + service breaks of nuclear power plants Jarek Kurnitski 11.5.2010 © Sitra 2010
  23. 23. Demand change analyses (emissions response to astep change in the demand) + or – step change in Change in electricity or emissions ? district heat • In the electricity production especially carbon-neutral capacity is limited • District heat CHP is produced against heat load without similar lack of capacity (demand change has no effect on the specific emission) • Construction of new buildings or renovation of existing ones means changes in the demand responded by electricity market • To account emissions of the step change we need to know a link between a new or non-appearing energy use in a building and energy production source (i.e. which type of plant will generate or is cutting down this energy production) Jarek Kurnitski 11.5.2010 © Sitra 2010
  24. 24. Demand change of electricity: allocation according tovariable cost• The change in the demand is allocated typically to the production source with highest variable cost as production sources have limited generation capacity and different variable cost• Similar order of variable costs for the whole EU and Finland• Hourly calculation: if enough generation capacity with lower variable cost is available, then the demand change will be allocated to that capacity (CHP or hydro). Jarek Kurnitski 11.5.2010 © Sitra 2010
  25. 25. Results for current situation (2007)Specific CO2 emissions by new or non-appearing electricity use (demand change)for current situationCurrent situation (year 2007) Total Separate CHP electricity Industrial Weighted electricity conventional generation CHP average specific generation thermal power emission Specific emission 279 893 439 190 814 kg(CO2)/MWh Share of the demand change 90 % 2% 0% • Results show that during 90% of the time of the year the demand change will be allocated to the separate conventional thermal power, 2% to CHP and the rest for carbon-neutral production (not shown in the Table). • This means that an hourly weighted specific emissions by new or non- appearing electricity use is as high as 814 kg(CO2)/MWh that is average emission of total generation by factor 3. Jarek Kurnitski 11.5.2010 © Sitra 2010
  26. 26. Scenario of 1600 MW new nuclear energy • We calculated a simple scenario, where new 1600 MW of nuclear energy will replace only separate conventional thermal power with no changes in energy demand structure (calculated with 2007 data)Specific CO2-emissions of the demand change for the scenario where 1600 MWnew nuclear energy replaces only separate conventional thermal power 1600 MW new nuclear Total Separate CHP electricity Industrial Weightedpower replaces only separate electricity conventional generation CHP average specificconventional thermal power generation thermal power emission Specific emission 137 893 439 190 466 kg(CO2)/MWhShare of the demand change 24 % 57 % 0% • 1600 MW new nuclear power decreased an average specific emission by almost of factor 2, but the ratio of the demand change and average specific emission values even increased to 3.4. Jarek Kurnitski 11.5.2010 © Sitra 2010
  27. 27. Energy carrier factors for demand change relative to specific CO2-emission of oilSpecific CO2-emissions of district heating and electricity (weighted average)relative to light fuel oil (heating fuel oil) CO2-emission factor Light fuel oil Electricity District (heating fuel oil) (weighted average heating specific emission) Specific emission 267 814 219 kg(CO2)/MWh Current situation (year 2007) Energy carrier factor 1 3.0 0.8 Specific emission 267 466 219 1600 MW new nuclear power kg(CO2)/MWh replaces only separate conventional thermal power Energy carrier factor 1 1.7 0.8 • When calculated with 2006 data, the emissions are slightly higher for electricity, leading to factor of 2.1 instead of 1.7 (and 3.2 instead of 3.0) Jarek Kurnitski 11.5.2010 © Sitra 2010
  28. 28. Energy carrier factors for selected scenarios 900 800 Specific emission, kgCO2/MWh 700 600 500 400 300 200 100 0 2005 2010 2015 2020 2025 2030 Electricity, basic scenario Electricity, "less nuclear" Electricity, "more nuclear" District heat estimate Demand change of electricity How to quantify the factors between average and demand change values? Jarek Kurnitski 11.5.2010 © Sitra 2010
  29. 29. Demand change in district heating energy use• The total CO2 emissions of Finnish electricity generation and district heating production if electricity use is kept constant, but district heating is reduced (e.g. additional insulation of existing multi-storey buildings) or increased• ⇒ Due to CHP, the total emissions do not depend on the amount of district heat used Total emissions of electricity and district heat 30 25 production, milj. t CO2 20 15 10 5 0 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.295 1.3 1.4 1.5 Ratio of the district heat demand change (1 = current situation, 0.5 = 50% reduction, 1.5 = 50% increase) Jarek Kurnitski 11.5.2010 Electricity generation District heat production © Sitra 2010
  30. 30. District heat replacing electricity use or vice versa• The total use of electricity and district heat is kept constant: - The ratio of 1 corresponds to the current situation, the ratio 0.5 means that half of current district heating energy used is replaced by electricity use and 2 that the current district heating use is doubled and electricity use reduced correspondingly• ⇒ Replacing district heat by electrical heating drastically increases total emissions Jarek Kurnitski 11.5.2010 © Sitra 2010
  31. 31. Demand change analyses with flexible capacity • Main principle: energy system model allowing both changes in the demand and production capacities, annual balance calculation 1. Select reference electricity and district heat production (e.g. 90 TWh el. and 33 TWh DH, repeat the calculation for other relevant values) 2. Define rules for production sources/capacities allowing to introduce new capacity to cover increased demand: - production sources with fixed capacity, hydro and nuclear (fixed capacity can be selected as input parameter) - production sources with flexible capacity, in this case condensing power and CHP - limits for district heat produced by CHP, 70…80% in this case - wind power and solar electricity fixed in this case, but can be treated with similar rules if considered flexible 3. Introduce a step change of heat and electricity demand (+3 TWh in this case) and solve energy production balance by minimizing emissions or production cost 4. Results: emissions and cost caused by +3 TWh electricity or heat production ≡ specific emission factors of the studied scenario Jarek Kurnitski 11.5.2010 © Sitra 2010
  32. 32. Finnish case study• +3 TWh step change of heat or electricity demand• 80 and 90 TWh reference electricity production and 33 TWh district heat production• Flexible capacity of separate condensing power and CHP• Nuclear energy capacity fixed, several capacity values calculated• Hydropower and wind power fixed• Limits for district heat produced by CHP, to be between 70 and 80%Specific emission (energy method) and cost data used:Production source Fuel cost Specific emission milj. EUR/TWh kgCO2/MWhNuclear energy 5 0Separate condensing power 25 900CHP electricity 15 300CHP district heat 18 300Separate district heat 22 225 Jarek Kurnitski 11.5.2010 © Sitra 2010
  33. 33. Emissions by + 3 TWh with flexible capacity 50 +3 TWh El. +3 TWh DH DH 33 TWh El. 90 TWh 45 40 +3 TWh El. DH 33 TWh +3 TWh DH El. 90 TWh 35 CO2-emissions, Mt 30 25 20 15 10 5 0 22,5 TWh nuclear energy 35,5 TWh nuclear energy • + 3 TWh electricity increased emissions by factor of 4,0 relative to + 3 TWH district heat (0.68 Mt vs. 2.7 Mt) • This factor of 4 would change to 3, if separate district heat production is not used • Results confirm that relevant selection of energy carrier factor for electricity should be close to the demand change values, not average values of specific emissions Jarek Kurnitski 11.5.2010 © Sitra 2010
  34. 34. Conclusions 1/2• Energy carrier factors may be based on CO2-emissions, primary energy (usually non-renewable) or on energy policy considerations• Primary energy factors are relevant for fuels, but for nuclear energy depend by factor 3 on the definition used• Specific CO2-emissions factors are scientifically sound (independent on definitions), but average factors cannot be used for regulative purposes, because they may guide to increased electricity use, which will consequently increase emissions as shown in the Finnish case study• Finnish average specific emission based factors (2000-2007): - electricity 1.0 - district heat 0.8 - oil 1.0 (reference)• Average factors for electricity and district heat are very close, but replacing district heat by electrical heating drastically increased total emissions in the Finnish case study and vice versa Jarek Kurnitski 11.5.2010 © Sitra 2010
  35. 35. Conclusions 1/2• Hourly demand change allocation increased electricity factor from 1.0 to 3.0 and analyses both with fixed and flexible capacity showed that the factor caused by demand change is 3 to 4 times higher than the average one• Energy system scenario calculations confirmed that relevant selection of energy carrier factor for electricity should be close to the demand change values, not average values of specific emissions• Using the rule of 3 x average specific emission, one can easily calculate electricity factors for future scenarios, i.e. if the Finnish average factor will be reduced to 0.6 in 2020, the electricity factor will be 1.8• Proposed Finnish factors are: electricity 2, district heat 0.7, fossil fuels 1.0• Higher energy carrier factor for electricity means in the energy performance design that electricity is more valuable energy than fuel energy or district heat. Such building regulation will generally promote for more effective electricity use in buildings and limit wasteful use of electricity.• Energy carrier factors are not constant, as depending on production sources, and are subject of revision with relevant interval of about 5 years Jarek Kurnitski 11.5.2010 © Sitra 2010