
It is broadly accepted that wind turbines do not emit CO2 at the point of generation. However, in common with all types of power station, it is emitted during their construction and, through damage directly inflicted on the construction site, over a much longer period. The total debt will vary from site to site but will comprise some or all of the following; • Emissions arising from fabrication (steel smelting, forging of turbine columns, the manufacture of blades and the electrical and mechanical components); • Emissions arising from construction (transportation of components, quarrying, building foundations, access tracks and hard standings, commissioning); • The indirect loss of CO2 uptake (fixation) by plants originally on the surface of the site but obliterated by construction activity including the destruction of active bog plants on wet sites and deforestation; • Emissions due to the indirect, long-term liberation of CO2 from carbon stored in peat due to drying and oxidation processes caused by construction of the site. It is important to recognise that peat is a major store of carbon accumulated from dead plant remains over many millennia. It is held in perpetuity because the bog’s wetness and acid conditions prevent the access of oxygen and inhibit the growth of bacteria which would otherwise rot the vegetation. Draining peat for construction reverses both these long-term processes: the soil is exposed to the air, the carbon is converted to CO2 and released slowly to the atmosphere. Several papers from the wind industry in Denmark and the UK have addressed the first two points with estimates of payback time ranging from about six to 30 months. However, the industry rarely, if ever, considers the last two. This is a fundamental omission as their contribution to the overall CO2 debt, in particular the last, can be far greater than all the others put together. This paper outlines a procedure for quantifying it. The guide has been prepared to enable anyone with access to the Environmental Statement (ES) that forms part of a Planning Application (PA) for a wind farm to estimate its CO2 debt. (If some of the requisite information proves to be unavailable, this ought to provide grounds for postponing consideration of the application and the commissioning of further assessment.) The results of the calculations described should be submitted to planning authorities or Public Inquiries as part of the arguments used in assessing the merits and demerits of an application.
Pollution
Energy Policy
General
UK