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A Carbon Calculator for Wind farms on Peatland

A Carbon Calculator for Wind farms on Peatland. Nayak D 1 , Perks M 3 , Miller D 2 , Nolan A 2 , Gardiner B 3 & Smith JU 1. 1 University of Aberedeen , Aberdeen, UK 2 Macaulay Institute, Aberdeen, UK 3 Forest Management Division, Forest Research, Midlothian, UK.

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A Carbon Calculator for Wind farms on Peatland

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  1. A Carbon Calculator for Wind farms on Peatland Nayak D1, Perks M3, Miller D2, Nolan A2, Gardiner B3 & Smith JU1 1University of Aberedeen, Aberdeen, UK 2Macaulay Institute, Aberdeen, UK 3Forest Management Division, Forest Research, Midlothian, UK

  2. The Scottish Government has ambitious targets for electricity generation by renewables 50% by 2020 31% by 2011 Scottish 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. Calculate carbon payback time Will greenhouse gas emissions from peatlands exceed carbon savings due to the wind farm? • If (carbon payback time) > (lifetime of wind farm), • wind farm does not provide carbon benefit

  5. Total losses (t CO2 eq.) Annual emission savings (t CO2 yr-1) Carbon payback time (years) Carbon Payback Time

  6. …depend on counterfactual energy source Annual Emission Savings Baggott, et al (2007). http://www.naei.org.uk/reports.php. Report AEAT/ENV/R/2429 13/04/2007 DUKES (2007). http://www.berr.gov.uk/energy/statistics/source/electricity/page18527.html

  7. Emission factor (t CO2 MWh-1) Turbine capacity (MW). Capacity factor (%) Annual emission savings (t CO2 yr-1) Number of turbines Annual energy output (MW yr-1) Carbon emission savings of wind farms

  8. Total losses (t CO2 eq.) C fixing potential Dissolved organic carbon Production, transportation, erection, operation, dismantling Forestry clearance Removed peat Habitat improvement Loss of C due to drainage Backup power generation Total Losses

  9. Change in C dynamics of peatlands Loss of carbon fixing potential of bog plants Loss of carbon from removed peat Loss of carbon from drained peat Loss of Dissolved and Particulate organic carbon Gain of C due to habitat improvement

  10. Site Specific Methodology Loss of carbon (CO2) from drained peat Water table depth (m) Peat temperature Rate of CO2 emissions (t CO2 eq. yr-1)

  11. Site Specific Methodology Loss of carbon (CH4) from drained peat Rate of CH4 emissions (t CH4 yr-1) Water table depth (m) Peat temperature

  12. 480ha felled & improved plantation 30% capacity factor 67 x 2MW turbines 385ha improved degraded bog 15m 15m Access tracks: 24600m floating roads 40m 20m 2m deep Example site – Central Scotland Extent of drainage: 100m Site fully restored on decomissioning

  13. Emission Factors

  14. Example site – Central Scotland Total carbon payback time 2.3 years

  15. 30% capacity factor 67 x 2MW turbines 385ha improved degraded bog 15m 15m Access tracks: 24600m floating roads 40m 20m 2m deep 480ha felled plantation Not improved! Example site – Central Scotland 480ha felled & improved plantation Extent of drainage: 100m Site fully restored on decomissioning

  16. Example site – Central Scotland Total carbon payback time 7.3 years

  17. 30% capacity factor 67 x 2MW turbines 15m 15m 40m 20m 2m deep Example site – Central Scotland Floating roads sink Extent of drainage: 100m

  18. 30% capacity factor 67 x 2MW turbines 15m 15m 40m 20m Floating roads sink 2m deep Extent of drainage: 100m Example site – Central Scotland

  19. 67 x 2MW turbines Example site – Central Scotland Very High

  20. Example site – Central Scotland Total 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. Annual power output (MW)

  23. Life time carbon emissions

  24. Carbon payback time Keyholing (Outwith): 3.5 yrs Large clearing (Within): 7.2 yrs

  25. Conclusion • Highest C losses from decomposition of soil organic matter • This can be reduced by developing wind farms on mineral soil. • With good management practices, carbon benefits can be achieved even on peats • Preliminary results shows keyholing with SRF can be a good forest management practice.

  26. 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)

  27. Thank you All

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