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From Leon Freris, Centre for Renewable Energy Systems Technology, Loughborough University

Ralph Ellis writes that “the cost of building wind farms needs to be doubled as a megawatt of back-up power needs to be commissioned for every megawatt of wind power” (22 March, p 30).

Bodies such as the Royal Commission on Environmental Pollution and the Performance and Innovation Unit of the Cabinet Office have studied these matters in depth. Does Ellis think that this basic “flaw” in the government’s arguments has escaped the attention of the eminent independent scientists and engineers on these committees?

Electrical power systems are designed to cope with substantial and unpredictable changes in demand, by means of partial loading of the generating equipment, pumped storage schemes and other mechanisms. It can be shown through statistical analysis that the variability of relatively small inputs from wind power or from other variable renewable sources would be swamped by the variability of demand.

Even if wind power were to supply the same amount of energy as the present nuclear contribution in Britain, the operational drawbacks due to the uncertainty associated with wind variability would be small, and very little or no extra back-up generation would be required. These facts are supported by the experience of national grids with large contributions from wind power, such as Denmark’s.

It is extremely frustrating for people who work and research in the field of renewables to read erroneous views such as those of Ellis, which are then picked up by the lay public and often propagated by uninformed journalists who wish to downplay the potential contribution of renewable energy.

Loughborough, Leicestershire, UK