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 Articles

October 2006 

Wind Turbines: are they economically viable in Horsham?

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?

There is 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 distribution systems.

  • 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.
    Ref: www.draxpower.com/corporate.php

  • Assuming historic 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.

  • Although the 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:

  1. Offshore Wind

    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.
     

  2. Domestic Wind in Horsham

    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 www.windsave.com and www.diy.com), 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 installation cost.

Conclusion

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.

Other Options

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 worth while.

Other websites to visit include:
www.buildingforafuture.co.uk
www.windandsun.co.uk
www.bwea.com