Mini-turbine on every Scot's roof: A Windsave Dream

British Gas has signed an agreement with the developers at Windsave, to market install and maintain residential roof-top windmills, and is to carry out trials in Scotland and the South West of England later this year. Pre-trial projections are that the mini-mills could save householders up to GBP100 a year on their electricity bills, a third of the average annual total. Payback period is projected to be under 6 years.

The roof-top TV antenaes that appeared in the 1950's led to a mass race to bolt one on the chimney of almost every home. Make these contingent for TV reception and it would be a done deal.Factoids:

Windsave says the roof-top units are seven times cheaper to install than the equivalent solar panels, generating around 1kW of power.

Each one generates around 45 decibels, which is the equivalent of a person talking in a normal voice.

There's a huge debate around how much power an "average" home needs, with the range typically starting at 1.4kW and going as high as 5kW. The extremes are not the basis for a market, however. A retired grandmother living on fixed income won't be buying a mini-turbine, even though it might provide nearly all her power for days on end. Likewise, the McMansion man, seriously downing the power, is unlikely to deface the roof-line view from the road, especially if its bought on an interest only loan, and the bank would frown on Beverly Hillbilly style mods. It's the 4 beds, two baths and no pool, with 2.13 persons that's closer to the mark: 2kW maybe. Optimum, if the lots are surrounded by green space and the noise less likely to offend a neighbor.

My concern would be resonance from the roof joists transmitting turbine vibration to the home interior, a topic not mentioned in the news items. The trials will be most interesting.