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You imply in your leading article (“uåX˜äŠÊ˜·³Ç, January 1997) that it was unfortunate that some German swineherd discovered that coal has a use as fuel. You should be grateful that he did. If he had not -- and no one else had -- there would not have been the steel industry as we know it today. The wind industry requires steel and other metal products as much as the rest of us. It is probable that the smelting of metals was discovered in similar ways -- by the stones for some fire hearth happening to be metallic ores.

It is very reasonable for the wind energy industry to be optimistic, but it must be realistic too. You state that "all our electricity needs could come from biomass, sun, wind and water." This is just not true. While there is plenty of renewable energy in existence at any time much of it is not exploitable, and may well never be. Writing on a night when the temperature is below zero and there is very little wind, I do not want to be dependant renewables for my electricity.

However, I am quite happy to use renewable energy produced electricity when its production is competitive. I am using biomass to provide some of the heating of my house.

Storage is no answer to the variability of renewable energy; it could not possibly be on the required scale. Our Dinorwic Power Station in Britain is a very large pumped hydro station but it can only supply about 1700 MW for a maximum of five hours; this is about 1% of our daily consumption of electricity. Storage back up for wind turbines would require two to three weeks capacity. No pumped hydro scheme could reasonably store even 12 hours supply. Compressed air energy storage using underground salt caverns for storage, like the plant at Huntorf in Germany, could give rather longer periods, perhaps two days. In emergency the compressors and turbines could be used together as straight gas turbines.

Right to ask questions

Public and political discussions are right to question if we should spend more on renewables. The technologies for biomass, sun, wind and water are substantially understood. In the case of water I mean hydro and tidal. It is extremely unlikely that wave power will ever make as much contribution to electricity supply as the present level of wind energy in this country; floating offshore devices are not capable of withstanding winter storms. There is little need for more research in renewable energy. It is a matter of making the most of opportunities for exploration. The wind energy industry should concentrate its efforts on these.