We went for the day with Devi, Matthew and Rosa to the Green Homes Show in Builth Wells. They were interested in wood-chip boilers, but were not altogether convinced.
I focused on the wind turbine stand by nextgenerationturbines.com. The one they were displaying looked pretty big to me.
In fact it was only 1.8 kW, which wouldn’t be enough for us. It’s a new model made in the US called Skystream 3.7 costing £6,500 without the base. It needs a 2 x 2 meter base, 1 meter deep. For a 5kW turbine we’d have to go for an older design like the Proven from the US that would cost around £20,000. The helix designs start at around £38,000.
They claimed that Skystream 3.7 will generate between 3,000 and 7,000 kWh per year depending on location and wind resource, so a Skystream could generate as much electricity as the average household uses in a year (4,700 units per year).
If a Skystream produces 5,000 units per year, this is worth up to £1,000 per year and will reduce carbon emissions by over 32 tonnes of CO2 over 15 years.
Leaving aside the two implied ‘ifs’, this suggests it would pay for itself in around 8 years.
But is it worth covering only part of our emissions, let alone our neighbours, if it’s their land we need to put it on? I asked about using 3 of these instead of one bigger one (=total of 5.4 kW and £24,000), so that each household could be separate. He said they would have to be 5 diameters apart. Probably not a good idea, since output increases exponentially with rotor diameter.
I was re-energised about the importance of growing our own food – and found this table helpful, showing which crops offered the best value.
And Dick Stawbridge from It’s Not Easy Being Green was practical and amusing – better than his on-screen persona.
One very interesting thing he said was that the best solar collector is woodland. OK so how do we make more use of ours? I looked up theoretical options for generating our electricity from heat (wood-burning stove), but there’s nothing available yet at a domestic level.