Calculating Carbon Budgets of Wind Farms on Scottish Peatlands

The reliability of calculation methods for the carbon emission savings to be achieved in Scotland by replacing power generated from fossil fuels (and other more conventional sources) with that produced by large-scale wind farm developments is a cause for concern, largely in relation to wind farms sited on peatlands. Scottish Government policy is to deliver renewable energy without environmental harm, and to meet biodiversity objectives including the conservation of designated wildlife sites and important habitats such as peatlands. The implications for carbon emissions of developing a wind farm are, therefore, just one aspect of the suite of considerations that the planning system takes into account. This paper presents a simple methodology for prospectively calculating the potential carbon emission savings to be realised by developing wind farms on peatland, forestland or afforested peatland. The total carbon emission savings of an individual wind farm are estimated by accounting emissions from the power source that will be replaced by wind power against: loss of carbon due to production, transportation, erection, operation and dismantling of the wind farm components (the infrastructure overhead); loss of carbon due to backup power generation; loss of carbon stored in peat and forest; loss of carbon-fixing potential of peatland and forest; and carbon savings due to habitat improvement. Most of the carbon losses are determined by national infrastructure, but those from peat soil and plants are influenced by site selection and management practices. The extent of drainage around each constructed element of the wind farm is a major factor for greenhouse gas emissions. Consideration of an example site with a low extent of drainage, where management practices that minimise net carbon losses (e.g. undrained floating roads, habitat improvement and site restoration on decommissioning) were used indicates that emissions from the soil and plants may cancel out as little as < 6% of the potential carbon savings, even on peatland. However, if the soil had a high extent of drainage and management practices that minimise carbon losses were abandoned, greenhouse gas emissions from the soil and plants could amount to 77% of the wind farm’s gross carbon savings; in other words, even though the development would not be a net cost in terms of greenhouse gas emissions, it would not provide much benefit. Thus, the development of wind farms on peat as opposed to mineral soils incurs a much greater risk that the potential net saving of greenhouse gas emissions will be significantly reduced by poor site management practice. This means that good site selection and management is of the utmost importance if wind farms are to be developed on peatlands.