HAVING digested Jenny Hogan's defence of wind power ("Time truth was told about the vital role of renewables in our wellbeing," Agenda, The Herald, April 22), I feel I must respond.

As the policy director of Scottish Renewables she is clearly concerned that wind energy is getting an increasingly bad press because of rising constraint payments with wind farms being shut down by the National Grid controller, and being paid for not producing electricity. By her own estimate £39m was paid to UK wind farms for this reason over the last 12-month period.

Her defence seems to be that fossil fuel generators are also paid for not putting power on the grid - about £270m over the same period. What she does not point out, or perhaps does not understand, is that the majority of these payments are also due to the deployment of wind power, forcing the fossil fuel power stations to operate less efficiently.

Wind may well be responsible for nearer to £200m of constraint payments for our bills, rather than the £39m declared.

It used to be the case that a small "spinning reserve" was all that was needed at some gas-fired power stations to cover for the occasional unexpected blips in supply or demand on the grid caused by unit failure, weather damage or unexpectedly high or low customer demand. However these were rare events, probably amounting on average to no more than one incident per month.

The advent of wind power with significant amounts of variable and unpredictable power spikes and slumps being offered to the grid coming from many wind turbines powering up or down more or less together, forces more conventional power stations, especially gas-fired power stations, to run or be constrained much more frequently.

For example, over the 30 days of a recent November, six very large power spikes and eight almost complete power slumps were experienced from the combined output of all wind farms in the UK. Constraint payments would have been made on all of these occasions, both to the wind farm operators and to those companies providing the balancing reserve power.

Renewables are of course a very mixed bag - hydro, biomass, and solar are very much more controllable and predictable technologies, and at the level they are deployed, cause no real problems for the grid.

Wind power is vastly different, expensive and inefficient in ways that we have yet to get our minds fully around.

Bruce McIntosh,



Castle Douglas.