Summary These slides show, one by one, the power per unit area of most big wind farms in Britain. The motivation for this work is to get a feeling for the area that would be occupied by wind farms making a substantial contribution, such as 20 GW average power in Britain. I went through the Renewable Obligation Certificate records for all wind farms, looking at any farm with 7 or more turbines, with at least one year of data at full operation. I got the energy data partly direct from https://www.renewablesandchp.ofgem.gov.uk/ and partly from the helpful summary collated by Oswald Consultancy and the Renewable Energy Foundation. I found each farm on an Ordnance Survey map, and estimated the area of the wind farm (taking into account the turbine diameters, as discussed on my blog). All maps are (c) Ordnance Survey, from the GetAMap service. I have marked in red on each map the approximate "boundary" I assumed for each farm. Obviously most of these early wind farms are located in excellent hilltop spots. We might thus expect the power densities of future farms to be lower. The next slide shows all the data on one plot; the final slide shows the averages.