1. 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

2. The Scottish Government has ambitious targets for electricity generation by renewables 31% by 2011 50% by 2020 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. Will greenhouse gas emissions from peatlands exceed carbon savings due to the 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 (years) Total losses (t CO 2 eq.) Annual emission savings (t CO 2 yr -1 ) Carbon Payback Time

6. Annual Emission Savings Counterfactual Energy Source Emission factor (t CO 2 MWh -1 ) Grid Mix0.43 Fossil Fuel Mix0.607 Coal Fired0.78 …depend on counterfactual energy source Baggott, et al (2007). http://www.naei.org.uk/reports.php. Report AEAT/ENV/R/2429 13/04/2007 http://www.naei.org.uk/reports.php. Report AEAT/ENV/R/2429 13/04/2007 DUKES (2007). http://www.berr.gov.uk/energy/statistics/sourc e/electricity/page18527.html http://www.berr.gov.uk/energy/statistics/sourc e/electricity/page18527.html

7. Carbon emission savings of wind farms Annual emission savings (t CO 2 yr -1 ) Emission factor (t CO 2 MWh -1 ) Capacity factor (%) Number of turbines Turbine capacity (MW). Annual energy output (MW yr -1 )

8. Backup power generation Total Losses Total losses (t CO 2 eq.) Production,transportation,erection,operation,dismantling Habitatimprovement Forestryclearance Dissolved organic carbon Removedpeat Loss of C due to drainage C fixing potential

9. Change in C dynamics of peatlands 1.Loss of carbon fixing potential of bog plants 2.Loss of carbon from removed peat 3.Loss of carbon from drained peat 4.Loss of Dissolved and Particulate organic carbon 5.Gain of C due to habitat improvement

10. Loss of carbon (CO 2 ) from drained peat Site Specific Methodology Rate of CO 2 emissions (t CO 2 eq. yr -1 ) Peat temperature Water table depth (m)

11. Loss of carbon (CH 4 ) from drained peat Site Specific Methodology Water table depth (m) Rate of CH 4 emissions (t CH 4 yr -1 ) Peat temperature

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

13. Emission Factors Bog Emission factor Rate of CO 2 emission in drained soil (t CO 2 ha -1 yr -1 ) 24.3 Rate of CO 2 emission in undrained soil (t CO 2 ha -1 yr -1 ) 0.26 Rate of CH 4 emission in drained soil ((t CH 4 -C) ha -1 yr -1 ) -0.005 Rate of CH 4 emission in undrained soil ((t CH 4 -C) ha -1 yr -1 ) 0.50 Fen Rate of CO 2 emission in drained soil (t CO 2 ha -1 yr -1 ) 64.62 Rate of CO 2 emission in undrained soil (t CO 2 ha -1 yr -1 ) 5.12 Rate of CH 4 emission in drained soil ((t CH 4 -C) ha -1 yr -1 ) -0.004 Rate of CH 4 emission in undrained soil ((t CH 4 -C) ha -1 yr -1 ) 0.56

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

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

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

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

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

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

20. Total carbon payback time 23 years Example site – Central Scotland

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 optionDetails No felling Trees remain right up to turbines Key holing 100m radius (3.14 ha) around each turbine i.e. 195 ha Large clearing 500 ha felling in a block around the turbines, 500 ha forestry remaining Clearfell All surrounding 1000 ha of forest cleared Key hole SRF (Outwith) Clearfell occurs, replanted with SRF on 25yr rotation ~10m height leaving 3.14 ha bare for each turbine. SRF used as biofuel Key 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 biofuel Large clearing SRF Clearfell occurs, replanted with SRF on 25yr rotation ~10m height leaving 500 ha block bare for turbines. SRF used as biofuel Large 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)

24. Life time carbon emissions

25. Carbon payback time Keyholing (Outwith): 3.5 yrs Large 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