ENERGY
Wind turbines:
Micro, small or big?
are you thinking of installing a wind turbine at your business?
Paul allen looks at the factors that need to be taken
into consideration.
Small wind
and planning permission gained, along with a
small wind turbines are most suited for use by suitable grid connection.
businesses that are either connected to mains
electricity supply (on-grid) or alternatively
Micro-generation scheme
using diesel generators or batteries (off-grid). When calculating whether a wind turbine will
typically with blade diameters of more than be economically viable two issues need to be
two metres small wind turbines are set on free taken into consideration.
standing towers 9 to 30 metres high. Firstly, what is the actual energy output that
there has been a lot of debate over the the turbine will deliver? traditionally many
last three years over the benefits of the two of the energy claims of manufacturers were
main types of small wind turbine designs more hopeful than accurate. but british and
- horizontal axis wind turbines (haWt) and international standards, including IEC and
vertical axis win turbines (VaWt). the bWea small Wind systems Performance
i have to admit to being a little biased Standard, now provide reliable benchmarks
on this debate as iskra only manufactures for energy output.
W
ith unstable energy horizontal axis turbines. theoretically vertical Plus, by the end of this year all turbines
costs and increasing axis wind turbines can be as efficient as will need to meet the criteria set down by the
environmental pressure horizontal, but in engineering reality they are micro-generation certification scheme (MCS)
a growing number of considerably less efficient. that has been designed to provide reassurance
businesses are considering the use of wind this is because the aerodynamics cannot be to consumers that both products and installers
turbines to power their offices, warehouses or optimised with the blades being both upwind meet robust quality and performance criteria.
work sites. and downwind during one revolution. Secondly, purchasers need to allow for
Basically, there are three main types of the forces on the turbine are also more the cost of installation, available grants and
wind turbines - micro, small and big. severe, being 'cyclic', and energy is often payment for feeding into the grid.
Micro-wind turbines typically have a consumed 'motoring' these turbines during Installation costs depend on location, size
diameter of less than two metres and are start-up. To put both designs in context, there of the tower, distance from the property and
mounted directly to the side or the top of a are no vertical axis turbines being used in big ground works.
building, often in towns and cities. wind to generate utility levels of electricity. Public sector and not for profit
there is considerable debate about how organisations can get government grants of up
efficient these turbines are.
Installation
to £10,000 or 50% of the turbine's cost.
but following the publication of the encraft the key piece of information for any business From April 2009, the amounts earned
Warwick micro-wind trials earlier this year considering installing a wind turbine is the by turbine owners under the Renewable
b&Q stopped stocking them and it makes average wind speed for the business's location. Obligation Certificate scheme will double
common sense as the wind in cities and towns the Carbon trust launched an online to around 8p per kWh produced (whether
will be interrupted and blocked by buildings. service in March this year - the wind yield consumed by the owner or not).
the wind around buildings is also more estimation tool - which allows uK businesses in 2010 a new programme of feed-in
turbulent, which decreases energy yield and to estimate their annual mean wind speed and tariffs will substantially increase the amount
increases the forces on the turbine structure the annual yield and carbon savings of a small of money that owners are paid for each unit
considerably. wind turbine. of electricity that they feed in to the national
big wind describes the utility-sized wind having ascertained that the average Grid. this is expected to bring the biggest
turbines that are built on the coastal, hilly and wind speed is viable and identified the sort single change in small wind turbine economics
mountainous regions across europe. of savings that could be made, there is a since the sector was created.
the multi-million investment required for structured process that needs to be followed
these turbines make them unaffordable for to ensure that the right turbine and tower are Pete Allen is CEO of Iskra Wind Turbines. For
even the biggest businesses. selected. the turbine needs to be properly sited more information, visit www.iskrawind.com
SuStainable SolutionS april 2009 29
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