Lower bills may not be blowing in the wind
There is no guarantee that putting a turbine on your roof will produce enough electricity to make worthwhile savings, writes Terry Slavin
Sunday June 25, 2006
The Observer
Ever since David Cameron announced he was planning to put a wind turbine on his new house in London, demand for the gadgets has soared. But that is as nothing compared with the interest that will be whipped up next week when the government announces it intends to scrap the need for planning permission for domestic energy generators, including solar panels and wind turbines.
The government will propose that homeowners can install mini wind turbines without applying for planning permission. Yvette Cooper, the planning minister, will tell MPs that, subject to a consultation, the government intends to make it much easier for people to use their homes as generators by cutting red tape that has so far acted as a brake on renewable energy.
This move, combined with B&Q's aim to sell rooftop wind turbines at its 'Warehouse' stores for about £1,600, including installation, and with 30 per cent of the cost offset by a government grant, means you won't need to be a member of Cameron's Notting Hill set to afford one.
But renewable energy experts, including government-funded agencies, fear that roof-mounted turbines could be another double-glazing overselling debacle in the making. They are concerned that the unregulated technology has not been adequately tested and that devices claimed by some manufacturers to produce up to a third of the average family's electricity needs could produce a fraction of that. Some also fear the turbines could cause structural damage.
'There's a lack of independent, verifiable evidence to support the performance claims of turbines attached to buildings,' says Kirk Archibald of the Energy Saving Trust (EST). 'There's been a lot of hype and a lot of interest, but you could have a situation where they get rolled out and don't work.'
One consultant who sits on the government's renewables advisory board and has undertaken extensive testing of some of the turbines says: 'We found the performance of them is on average between 10 and 25 per cent of what the manufacturers are claiming.'
Unlike solar panels, which were thoroughly tested with government field trials before their introduction, rooftop wind turbines have seen very little such testing, says Archibald. They were assumed to perform like larger wind turbines on poles sited in exposed areas, but air turbulence caused by neighbouring buildings and obstructions such as trees can affect performance dramatically.
Windsave, which makes the turbine that will be sold by B&Q and will be selling directly via the internet from August, says its 1.75 metre turbine produces 1,000-2,000 kilowatt hours of electricity a year. Renewable Devices says its Swift 2 metre turbine produces between 2,000 and 3,000 kwH of energy a year, and could save the householder up to £300 a year, including the value of green energy generation certificates.
But Archibald says that low wind speeds in urban areas mean that most installations will never come near that. 'In better locations we'd expect wind speeds of six metres per second, but in urban areas, with lots of other buildings around, you're probably looking at four [metres per second], and that will affect performance considerably.'
Nick Martin of the Hockerton Housing Project, a sustainable development in Nottinghamshire, is a construction expert who has monitored performance of much larger, pole-mounted turbines and investigated the claims of the rooftop turbine makers. He says that Swift and Windsave's performance claims 'defy the law of physics' and that they will produce much nearer to 10 per cent of the average household's energy needs.
It is an awkward situation for the EST, which administers a new Department of Trade and Industry programme to fund 30 per cent of the cost of small-scale renewables. The Swift and Windsave turbines were accredited under a previous government scheme, Clear Skies, which did not require them to meet performance criteria, Archibald says. Clear Skies rolled over into a new scheme, the Low Carbon Building Programme, in April, meaning that the two turbines still qualify for grants - although the government has not yet announced the criteria that products will need to meet.
Scottish and Southern Energy has a stake in Renewable Devices and is looking to offer the Swift turbine to another 400-500 customers this year. Business manager Nigel Ellis stands by the 2,000-3000 kwH performance claim, which he says is based on wind speeds of between 4.4 and five metres a second, but agrees that 'output does vary' and that obstructions, such as nearby trees or buildings, will eat into performance.
David Gordon, chief executive of Windsave, also defends the performance claims. He says that even at four metres a second, the turbine will produce more than 500 kwH a year, taking £60 off the average bill. Consumers will also be eligible to get a green energy certificate worth £60 from the government, taking the annual value of the electricity up to £120: 'And that has to be worth having.'
Shoppers will not just be able to pop a wind turbine in their trolley and head for the tills at B&Q, Gordon pointed out. They will be sold to order, and the company's installers will put them up only if windspeeds are at least 3.5 metres a second. This will be judged using data from the DTI, which has windspeeds for every postcode in Britain.
But the Hockerton Housing Project's Martin, says the DTI windspeed data is misleading: 'The DTI computer generator looks at topography but doesn't take into account fences, trees and buildings, which affect windspeeds.' He also worries about structural damage to houses if they are not installed properly: 'If you bolt it to the end of the gable of a Victorian house made with lime mortar, it's going to come apart.'
The consultant on the government's renewables advisory committee also noted vibration problems with some turbines that were 'more than the building [they were being tested on] could take'.
Windsave's sales literature warns that its wind turbines are not suitable for some roof types, including lime mortar, and says every building will be tested by its installers for suitability. Neither are all house types suitable for the Swift turbine, and Scottish and Southern will require a full structural survey by its engineers before a rooftop device is installed. Ellis says the availability of trained installers is limiting how fast it can go in rolling out the devices.
Meanwhile, Cameron's wind turbine of choice, the 1.1-metre diameter Stealthgen by Eclectic Energy, is too small for grant funding under the previous Clear Skies regime, which only funded turbines bigger than 1.7 metres. The Stealthgen costs about £3,000, including installation, but Peter Anderson, managing director of Eclectic, says he hopes it will be accredited for a grant under the new scheme. 'Of the three companies, ours is the smallest turbine and the most appropriate size for domestic houses,' he says, adding that it can be put on any building and produce about 660 kwH a year.
But he fears that the entire industry could be tarred if the claims of makers of larger wind turbines are not borne out: 'This is a viable technology, but we're concerned about the varying claims. There's a strong desire on everybody's part to develop UK standards for consumers and for the industry to be on a level playing field so that it develops professionally and consumers are protected.'
Find out more
So what should you do if you want a rooftop wind turbine? You might be better off waiting until the situation regarding planning permission is clear, and the accreditation scheme for the Low Carbon Building Programme is in place, but if you want to start the process rolling now:
· Call your local council to find out how difficult - and expensive - it might be to get planning permission. If you live in a conservation area, it's unlikely you'll get it, but there are exceptions. David Cameron's Notting Hill house is in a conservation area, but Alex Michaelis, who designed the renovations to Cameron's house, hopes he will be given permission. His company has previously received planning permission for Stealthgen turbines in another conservation area in Hammersmith and Fulham.
· RWE Npower has a microgeneration scheme that helps customers to apply for planning permission and grants. But of 250 customers on the scheme, only half received planning permission, with many local authorities telling them not to bother to apply. Chris Tomlinson, of the British Wind Energy Association, warns that the cost of getting planning permission could be from £600 to £3,500. ·
· Check the BWEA small wind website, www.bwea.com/small/index.html. This has links to the Low Carbon Building Programme for grant information and to the DTI to calculate wind speeds in your area. The Energy Saving Trust helpline is 0845 727 7200, or visit www.est.org.uk/myhome/ for information about grants, manufacturers and installers.
