What's wrong with this
picture?
Rooftop wind turbine madness in the UK.
(Picture from Paul
Gipe's site.)
THE ENERGY SAVINGS TRUST
•Wind turbines do work but only when installed
properly in
an appropriate location.
•There is a potential for delivering carbon savings and energy
generation from domestic small-scale wind turbines in the UK.
•The highest potential for successful household small-scale
wind installations is in Scotland.
•Wind speeds are difficult to predict and highly variable.
The Energy Saving Trust recommends that potential
customers first utilise the best available wind speed
estimation tools and then, where appropriate, install
anemometry to determine the wind speed distribution.
Data gathered through the field
trial
indicates that none of
the sites with building mounted turbines had average annual
recorded wind speeds of 4m/s or greater, and only a third of
free standing pole mounted turbines had average annual
recorded wind speeds of 5m/s or greater. It is therefore
likely that many sites in the UK have less of a wind resource
than previously predicted....
No urban or suburban building mounted
sites generated more than 200kWh or £26 per annum,
corresponding to load factors of 3 per cent or less. In some
cases, installations were found to be net consumers of
electricity due to the inverter taking its power (up to 10W)
from the mains supply when a turbine was not generating.
A
review by Paul Gipe
The Ampair perspective
New
Energy Focus report
Dutch small wind turbine trial suffers low wind speeds
HAWTs generally score much better than VAWTs in this test but there are
exceptions, notably the Swift (shown right) which seems to me to be a
bit of a disaster - a shame considering what nice people they are, and
near to my home town of Edinburgh.
A new Carbon
Trust study into the potential of small-scale
wind
energy has found that small wind turbines could provide up to 1.5
Terawatt Hours (TWh) per year of electricity (0.4% of total UK
electricity consumption) and 0.6 million tonnes of carbon dioxide
(MtCO2) emission savings. This is based on 10% of households
installing turbines at costs competitive with grid electricity, which
is currently around 12p per kWh.
The study also indicates that for the UK as a whole, the
majority of
electricity and carbon savings are available from small turbines in
rural areas - four times as much as urban areas irrespective of costs,
and considerably more given economic drivers. This is mainly due to
wind speeds generally being higher in rural areas. Turbines in
some
rural locations could provide cheaper electricity than the grid, but it
appears that in many urban situations, roof-mounted turbines may not
pay back their embedded carbon emissions.
The report published today marks the culmination of 18 months
research by the Met Office and Entec, and is partly intended for
government policy makers. It makes important recommendations to improve
existing policy measures, including that:
• A criterion should be used in any new grant schemes to
measure
likely carbon savings. This is to help ensure grants are awarded
to
installations which save reasonable amounts of carbon; and
• Higher
height limits for stand-alone turbines should be allowed under
permitted development rights. This is to help maximise the
overall
carbon savings of small-scale wind energy, given the sensitivity of
electricity generation to height.
Rooftop nonsense is alive and well in France. See this
article from Paul Gipe
It's hard to know whether to laugh or cry that these guys get public
acclaim for wildly oversold nonsense.
www.wind-works.org
elena
energie
|
in the city
(updated with response from RD Swift
turbines, and my email to BWEA)
Mostly now when I see these 'Swift' turbines they are under repair for
some reason. It looks awful.
The new certification body BRE have come out with new
guidelines for
estimating windspeed on urban sites that you can download.
These rules of thumb (see appendix suggest that the windspeed at
rooftop level is approximately 50% of what you would expect from using
the DTI (NOABL) data set that everyone relies on. That means 1/8
of the energy production.
The Carbon Trust have also brought out
a new
Windspeed
Estimator on line that is much better than NOABL
for built-up areas.
The Warwick
Urban Wind Trial project has
engaged in depth with the new market for urban, building mounted
wind turbines at a critical time in market
development. By taking the customer perspective and
combining technical monitoring with social research into the
impact of installations on public perceptions of energy
efficiency and wind, the project is providing the most thorough
and complete assessment to date of the efficacy of urban wind
systems in supporting UK energy and environmental
policies.
Further
evidence from the Warwick Wind Trials shows that most of the new
generation of rooftop turbines also fail to meet their claimed output,
often only achieving 30% or less. In many cases the inverter's
standby power consumption exceeds any power generated on urban sites.
The final
report is now available and it makes essential reading
for those who want to know about small scale urban wind realities (as
opposed to marketing spin).
"Renew-Reuse-Recycle is an online community all about what we can do to
stop or mitigate the effects of climate change.
"Some of our members have recently started logging their KWh output on
a monthly basis in a shared
Google Spreadsheet."
Siting of small VAWT turbines in the UK
Factors affecting the success of a wind turbine are :reliability,
windspeed, swept area, cost and efficiency. I found a Quiet Revoluiton
QR5 turbine at the botanic gardens in Edinburgh and I am checking out
these criteria.
There is a good rule of thumb that says a wind turbine should be 30
feet above any obstruction within 300 feet. Windspeed is highly
critical for energy production since the energy depends on the cube of
the windspeed. There is hardly any wind for turbines sited below the
'canopy layer' of the tree tops. For more details check the Carbon
Trust wind siting tool. The company state that "Please note that the
minimum recommended average wind speed for a QR5 is 5m/s." But they
were willing to sell one to go on this site, maybe just for
"demonstration purposes"?
Reliability is very important since the kilowatt hours of energy
generated will depend on the hours the turbine is available. The QR5 is
out of action so far as I am aware due to problems with the blade
attachments. Vertical axis turbines do have intrinsic fatigue problems
which along with the problems of starting and stopping, and the
problems of putting them on proper towers have made them a poor choice
for wind energy.
The turbine is a nice size (5m high x 3.1m in diameter) but in relation
to its cost it will not produce much energy even on a good 5 m/s site.
The turbine alone costs £25,000. It does not matter how efficient
it is it can never produce more than about 12,000 kWh per year at a
5m/s site, and the manufacturers claim 7,500 kWh per year. A HAWT of
similar size and a fraction of the cost would do the same.
Nice ornament? Or a big waste of money, and another big embarrassment
to the small wind industry? |
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E-mail
me at:
hugh@scoraigwind.co.uk