Wind Turbines: are they economically viable in
This turbine at Climping, near
Littlehampton, is well sited on the windy
coastal plain and generates a useful amount of
electricity for St Mary's School. But what of
its visual impact? And how
effective would it be in Horsham?
compelling evidence that CO2 emissions are
contributing to Global Warming and it would prudent to
reduce the current levels of these emissions. Wind
turbines generate clean and renewable energy with no
harmful emissions at the point of use. Exploitation
of renewable energy resources should have a beneficial
effect in reducing CO2 emissions.
Whilst there are environmental benefits
in exploiting wind power, there are also ‘hidden’
societal costs that are not being publicised. The case
is as follows:
New wind turbine
installations could not replace any significant part
of the existing infrastructure of the UK electricity
supply industry (ESI). This is because capacity has to
be based on peak usage (with a margin for breakdowns).
Wind power is unavailable for part of the time (and
only reaches peak output under favourable conditions)
and bulk electricity storage is not viable. Therefore
other power sources and their associated
infrastructure must be retained sufficient so as to
meet peak demands without any contribution from wind.
The cost per unit
of electricity charged to the consumer by the supplier
includes a substantial element of fixed
‘infrastructure’ charges as opposed to variable ‘fuel’
charges. Infrastructure charges include the costs of
financing and maintaining power stations, the
electricity transmission system and the local
As an indicative
estimate of fuel costs we can use the 2005 results of
Drax Power Ltd (operator of one of the most efficient
coal fired power stations in the UK) who spent £459.7M
on fuel to generate 23.2TWh, i.e. 2p per kWh. This
compares with a cost of around 8p per kWh paid by
domestic consumers in Horsham last year.
infrastructure costs remain unchanged, the ‘societal’
benefit of new domestic or large scale wind generation
would be limited to 2p per kWh generated. Although
wind turbines have no fuel costs, this benefit is
required to fund their infrastructure costs (repaying
capital investment and maintenance) and, in the case
of large scale generation projects, to finance
required extensions to the transmission system.
government may promote renewable generation by grants
so that it is economically viable for investors in
specific projects, overall the costs to society are in
excess of the 2p per kWh benefit.
Two case studies
can be considered:
Calculations are based on proposed offshore
projects in the Thames Estuary.
The proposed Greater Gabbard project (www.greatergabbard.com)
claims that it will generate 1750 GWh per annum from
500MW of capacity.
This gives a load factor of 1,750,000/(500x8760) = 0.4
[8760 is the number of hours in a year]
The proposed London Array project (www.londonarray.com)
is estimated to require an investment of £1.5Bn for
1000MW of capacity. Using the same load factor, this
gives an output from the project of 3500GWh per annum
which will avoid £70M of fuel costs (at 2p per kWh).
£70M gives around a 5% rate of return on investment
and would not even cover depreciation costs.
Therefore, to make this project viable the consumer
will have to recompense the developer more than 2p per
kWh generated, i.e. a higher cost than Drax.
Wind speeds in Horsham are not high. The DTI wind
speed data* suggests that an average of 4.7-4.9 m/s
(at 10m above ground) can be expected.
A wind turbine needs to be sited as far as possible
from trees, buildings, etc which might cause turbulence
(and a substantial loss of energy). Less than 10
metres above such obstacles and the output is likely
to be much reduced. In practice, it is impossible to
site a turbine in Horsham at sufficient height above
surrounding obstacles to make effective use of the
available wind energy. It is suggested in a recent
article (Building for a Future magazine, Autumn 2005)
that only 4 m/s may be available at many sites. This
seems reasonable for Horsham. An average of 4 m/s will
give an annual output of 441 kWh with a typical 1.75m
dia, 1 kW turbine (Windsave WS 1000, see
a load factor of only 5%.
441 kWh provides a ‘societal’ benefit of £8.80, based
on the avoided fuel burnt at Drax. Even taking a
high-end figure of 10p per kWh as the cost of
purchased power to the individual consumer, it only
equates to a saving of £44 per annum. This seems a
poor return for a unit costing £1600 + VAT (installed)
with a declared technical life of only 10 years. Even
if it lasts 20 years you will only have saved half the
Of the two cases, the offshore wind
represents much better value for money to Society.
Both examples have an installed cost of around
£1500/kW, however the offshore installation gives a
load factor of 40% compared with 5% for the domestic
installation and avoids eight times the CO2 emissions
for an equivalent investment.
Improved levels of
building insulation would give a much better rate of
economic & environmental return in the domestic
environment. This is particularly the case for new
buildings where it is easier to incorporate better
insulation. In view of the visual impact of wind
turbines in an urban environment, they are clearly not
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