We at gotwind.org welcome more wind generators, and micro-generation wind generators are a great step forward, however it is worth considering the facts.
Lengthy article - but well worth reading and considering.
'Windsave's performance claims defy the law of physics'
Please click below, Windsaves Chief Executive David Gordon admits the annual financial saving can be as little as £10
Sunday June 25, 2006
The Observer
Ever since the U.K's Conservative Member of parliament David Cameron
announced he was planning to put a wind turbine on his new house in London,
demand for the gadgets has soared.
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 £1,498, 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.'
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