– The turbine data for this are much smaller and fewer, but does provide data on the increase in carbon payback time for forested lands.
While it does show that there is eventually a payback over the loss 3-4 years instead of 6 months for non- forested lands, it notes that the additional changes to hydrology, can add more negative effects.
CO2 payback time for a wind farm on afforested peatland in the UK2010 | J.T. Mitchell, J. Grace,G.P. Harrison |mires-and-peat.netExcerpts:
The siting of wind farms on natural and afforested upland peatlands presents an interesting public policy dilemma. Such locations may offer developers attractive wind characteristics amidst sparse human settlement, but the associated disturbance of carbon from soils and vegetation may reduce the carbon benefits that can be derived from wind farm operation. T
“CO2 emissions caused by site disturbance may equal or exceed those resulting from the manufacture, operation and decommissioning of a wind farm. Secondly, although the calculations are site specific, wind farms on natural and afforested peatlands can deliver acceptable CO2 payback times of less than four years. …A more significant factor in the disturbance of afforested peatlands is the loss of sequestration, litterfall and below-ground carbon transport from trees, as well as the accelerated loss of dissolved and suspended organic carbon in streamflow as a result of clearfelling. Despite the technical case that the CO2 emissions avoided by installing a wind farm on an afforested peatland probably exceed the emissions caused by disturbance of the site, it should be remembered that CO2 payback time is a relative measure.
… The case for excavating and degrading peatland soil is supportable only as a lesser of evils. A higher portion of low-carbon power in the national electricity mix would reduce its CO2 intensity and extend the CO2 payback time if calculated on the basis of the full grid mix, thus weakening the case for building wind farms on natural and semi-natural sites. Wind power developers should be aware of greenhouse gas emissions associated with site development and make efforts to reduce the footprints of pad sites, buffer zones, roads and building works that disturb hydrology, forests and soils.J.T. Mitchell et al. CO2 PAYBACK TIME FOR A WIND FARM ON AFFORESTED PEATLAND IN THE UK, Mires and Peat, Volume 4 (2008–2010), Article10, http://www.mires-and-peat.net/, ISSN 1819-754X © 2010 International Mire Conservation Group and International Peat Society