The most recent statistics from the Department of Energy and Climate Change show that North Dorset consumes 290.8 GWh/yr
The last census shows 30,397 households, only 11% of those being flats. Quite a few of these dwellings already have PV installed on their roofs but that number is likely to increase substantially when PV becomes so cheap that it will make better financial sense to install it than pay for all your electricity from the grid. This grid parity (without subsidy) is expected to come about as early as 2020. More than half of houses have close to south facing roof space and it's reasonable to assume that 60% or so could accommodate a 4 kW array. These would generate around 65 GWh/yr
There are 3,800 businesses in North Dorset including farms. Not all will have their own roof space but all those steel sheds on industrial estates and agricultural barns have low pitched roofs that are viable for PV whatever their orientation. A quick look at Google Earth shows at least 50 big enough to take around 50 kW in the towns and farm barns would probably double that. So I estimate these could generate 5 GWh/yr.
There are already quite a few large and small ground mounted solar farms installed and enough space to generate the equivalent of the districts needs without impacting food production. A reasonably large solar farm is 10 MW generating 10 GWh/yr so 29 of those would equate to the district's annual consumption.
There are at least 6 small 20 kW wind turbines (up to 20 m mast and 7 m blades) in North Dorset tucked away virtually un-noticed. The landscape could easily accommodate 50 small turbines without travellers and walkers constantly coming across them. They could generate 0.35 GWh/yr.
The River Stour and its tributaries already has 4 hydro turbines installed at mills and weirs with another 5 to be installed soon and potential for at least 6. They range from 3.7 to 89 kW and in total could generate 1.75 GWh/yr.
Now the elephant in the room, which is big wind power They may be very much out of favour with a vocal minority punching well above their weight but the fact is that a 2.3MW on-shore wind turbine is the cheapest source of renewable electricity. It would require 60 of these to generate the equivalent of all the district's electricity and that could not be accommodated easily. I would say a maximum of 20 could be found a home and 10 would be more realistic and they could generate 48.5 GWh/yr
So North Dorset could generate equivalent to all its electrical need with;
65 GWh/yr from domestic roof tops
5 GWh/yr from commercial and agricultural roof tops
0.35 GWh/yr from small wind turbines
1.75 GWh/yr from hydropower
That leaves 218.7 GWh/yr to be found from a combination of large solar farms and wind turbines. Personally, I would like to see 10 large wind turbines, some of those to be clearly viewed from my back garden. That would mean 17 x 10 MW solar farms to take up the slack.
