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Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
Clad oct09 acoupar_dnayak (nx_power_lite)
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Clad oct09 acoupar_dnayak (nx_power_lite)

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  • 1. A Carbon Calculator for Wind farms on PeatlandNayak D1, Perks M3, Miller D2, Nolan A2, Gardiner B3 & Smith JU1 1University of Aberedeen, Aberdeen, UK 2Macaulay Institute, Aberdeen, UK3Forest Management Division, Forest Research, Midlothian, UK
  • 2. The Scottish Electricity generation by renewables 100 90 Government has 80 ambitious targets 70 60 for electricity (%) 50 generation by 40 30 renewables 20 50% 10 by 2020 0 31% 2010 by 2011 2015 2020 2025 YearScottish Government (2008)http://www.scotland.gov.uk/Topics/Business-Industry/Energy/19185/17612
  • 3. Wind farms are likely to be developed on peats – Less productive than arable mineral soils → no pressures on land use – On exposed sites → high capacity factor
  • 4. Will greenhouse gas emissions frompeatlands exceed carbon savings due tothe wind farm? Calculate carbon payback time If (carbon payback time) > (lifetime of wind farm), wind farm does not provide carbon benefit
  • 5. Carbon Payback Time Total losses (t CO2 eq.) Annual emission savings (t CO2 yr-1)Carbon payback time (years)
  • 6. Annual Emission Savings …depend on counterfactual energy source Counterfactual Emission factor Energy Source (t CO2 MWh-1) Grid Mix 0.43 Fossil Fuel Mix 0.607 Coal Fired 0.78Baggott, et al (2007). http://www.naei.org.uk/reports.php. Report AEAT/ENV/R/2429 13/04/2007DUKES (2007). http://www.berr.gov.uk/energy/statistics/source/electricity/page18527.html
  • 7. Carbon emission savings of wind farms pcap S fuel = 24 × 365 × × nturb × c turb × E fuel 100 Emission factor (t CO2 MWh-1) Capacity Number of TurbineAnnual emission factor turbines capacity savings (%) (MW). (t CO2 yr-1) Annual energy output (MW yr-1)
  • 8. Total Losses Ltot = Llife + Lback + Lfix + Ldirec t + Lindirect + LDOC + Lforest + Limprovemen tTotal losses(t CO2 eq.) C fixing potential Dissolved organic carbon Removed peat Forestry Production, Loss of C clearance transportation, due to erection, drainage operation, Habitat dismantling improvement Backup power generation
  • 9. Change in C dynamics of peatlands1. Loss of carbon fixing potential of bog plants2. Loss of carbon from removed peat3. Loss of carbon from drained peat4. Loss of Dissolved and Particulate organic carbon5. Gain of C due to habitat improvement
  • 10. Loss of carbon (CO2) from drained peat Site Specific Methodology 44 / 12 R CO 2 (Bog) = × ((6700 × exp(− 0.26 × exp(− 0.0515 × (( W × 100) − 50))) + ((72.54 × T) − 800) 1000 Water tableRate of CO2 emissions depth (m) Peat temperature (t CO2 eq. yr-1) 44 / 12 R CO 2 (Fen) = × ((16244 × exp(−0.175 × exp(−0.073 × (( W × 100) − 50))) + (153.23 × T ) 1000
  • 11. Loss of carbon (CH4) from drained peat Site Specific Methodology 1 R CH 4 (Bog) = × ((500 × exp(− 0.1234) × ( W × 100)) + ((3.529 × T) − 36.67) 1000Rate of CH4 emissions (t CH4 yr-1) Water table Peat temperature depth (m) 1 R CH 4 (Fen) = × ((−10 + 563.62 × exp(−0.097) × ( W × 100)) + (0.662 × T ) 1000
  • 12. Example site – Central Scotland 480ha felled & improved plantation 67 x 30% capacity factor 2MW turbines 385ha improved degraded bog 15m 15m 40m Access tracks: 20m 24600m floating roads2m deep Extent of drainage: 100m Site fully restored on decomissioning
  • 13. Emission Factors Bog Emission factor Rate of CO2 emission in drained soil (t CO2 ha-1 yr-1) 24.3 Rate of CO2 emission in undrained soil (t CO2 ha-1 yr-1) 0.26 Rate of CH4 emission in drained soil ((t CH4-C) ha-1 yr-1) -0.005Rate of CH4 emission in undrained soil ((t CH4-C) ha-1 yr-1) 0.50 Fen Rate of CO2 emission in drained soil (t CO2 ha-1 yr-1) 64.62 Rate of CO2 emission in undrained soil (t CO2 ha-1 yr-1) 5.12 Rate of CH4 emission in drained soil ((t CH4-C) ha-1 yr-1) -0.004Rate of CH4 emission in undrained soil ((t CH4-C) ha-1 yr-1) 0.56
  • 14. Example site – Central Scotland 400000 Gre enhous e Gas Em iss ions (t CO2 e q.) 300000 Carbon emissions 200000 100000 0 Carbon savings -100000 -200000Total carbon payback time 2.3 years
  • 15. Example site – Central Scotland 480ha felled plantation Not improved! 67 x 2MW turbines 30% capacity factor 385ha improved degraded bog 480ha felled & improved plantation 15m 15m 40m Access tracks: 20m 24600m floating roads2m deep Extent of drainage: 100m Site fully restored on decomissioning
  • 16. Example site – Central Scotland Greenhouse gas emissions 4500000Greenhouse Gas Emissions (t CO2 eq.) 4000000 3500000 3000000 2500000 2000000 1500000 1000000 500000 0 Total carbon payback time 7.3 years
  • 17. Example site – Central Scotland 67 x 30% capacity factor 2MW turbines 15m 15m 40m 20m Floating roads sink2m deep Extent of drainage: 100m
  • 18. Example site – Central Scotland 67 x 30% capacity factor 2MW turbines 15m 15m 40m 20m Floating roads sink2m deep Extent of drainage: 100m
  • 19. Example site – Central Scotland actor ap acity f 30% c 67 x 2MW turbines 15m 15m 40m sink 20m g roads Floatin ge: of draina Extent 00m 2 ep2m de Very High
  • 20. Example site – Central Scotland 4500000 Greenhouse gas emissionsGre enhous e Gas Em iss ions (t CO2 e q.) 4000000 3500000 3000000 2500000 2000000 1500000 1000000 500000 0Total carbon payback time 23 years
  • 21. New Developments in collaboration with Forestry Commision Forests-turbines-soils Calculator • Forest accumulated carbon calculated through simplified version of 3PGN model • Various felling options around turbine i.e. key holing, large clearing…….. • Option to replant SRF • Impact upon turbine output calculated through simple windflow / turbulence model
  • 22. Management option DetailsNo felling Trees remain right up to turbinesKey holing 100m radius (3.14 ha) around each turbine i.e. 195 haLarge clearing 500 ha felling in a block around the turbines, 500 ha forestry remainingClearfell All surrounding 1000 ha of forest clearedKey hole SRF (Outwith) Clearfell occurs, replanted with SRF on 25yr rotation ~10m height leaving 3.14 ha bare for each turbine. SRF used as biofuelKey hole SRF (within) 100m radius (3.14 ha) around each turbine felled, area keyholed replanted with SRF on 25yr rotation ~10m height. SRF used as biofuelLarge clearing SRF Clearfell occurs, replanted with SRF on 25yr rotation ~10m height leaving 500 ha block bare for turbines. SRF used as biofuelLarge clearing SRF 500 ha felling in a block around the turbines, 500 ha forestry remaining, area felled replanted with SRF on 25yr rotation ~10m height. SRF used as biofuel
  • 23. Annual power output (MW) 300000 250000Annual power output (MW) 200000 150000 100000 50000 0
  • 24. Life time carbon emissions 6000000Greenhouse Gas Emissions (t CO2 eq.) 5000000 4000000 3000000 2000000 1000000 0
  • 25. Carbon payback time 25 20Carbon payback time (years) 15 10 5 0 Keyholing (Outwith): 3.5 yrsLarge clearing (Within): 7.2 yrs
  • 26. Conclusion 1. Highest C losses from decomposition of soil organic matter 2.This can be reduced by developing wind farms on mineral soil. 3.With good management practices, carbon benefits can be achieved even on peats 4.Preliminary results shows keyholing with SRF can be a good forest management practice.
  • 27. Acknowledgements – Sally Baillie (Forestry Commission) – Clifton Bain (Royal Society for Protection of Birds) – Andrew Coupar (Scottish Natural Heritage) – Helen Jones (Scottish Government) – Sue Kearns (Scottish Government) – Martin Mathers (Scottish Renewables Forum) – James Pendlebury (Forestry Commission) – Geeta Puri (project officer, Scottish Government). – Peter Singleton (SEPA) – Guy Winter (Scottish Government)
  • 28. Thank you All

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