To say that windmills work 90% of the time, as Kerr MacGregor of Scottish Solar does (January 13), is true but misleading. The amount of power produced varies roughly with the cube of windspeed up to the optimum of about 24mph. Thus a 6mph wind does indeed produce electricity, but only about 1/64th of capacity, which will not keep many lights on. This is why windmills overall produce about 27% of their rated power performance. Whenever you see another politician saying that such and such new wind farm will produce power for 50,000 people, it won’t. Even with “planned downtime” – which, being planned, can be set for when demand is low – conventional generators are vastly more reliable.
Storing power is less feasible than suggested. The only serious method is the pump storage system we use at Cruachan which loses 25% of the power put into it due to inherent inefficiencies and is, in any case, comparable in expense to a new conventional generator. If onshore wind is already twice as expensive as coal generation and four times as much as nuclear, the additional expense of building more pump storage facilities can be imagined. As Denmark and Germany have found, the inherent instability of the system means that it is very difficult to get windpower above 10% of the grid.
All our political leaders know this and know that if we do not now start building the replacements for the 50% of our power produced by Hunterston, Torness and the high-emission coal plants due to close in the next decade and a half, we are going to have blackouts on a massive scale. Windmills are an expensive token to give the appearance of action. Despite the hysteria, nuclear is the safest and cheapest method of generating electricity, as well as being effectively CO2-free. If more of them do not find the guts to say so, we are going to have many more hypothermia deaths.
Neil Craig, 200 Woodlands Road, Glasgow.
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