An elegant solution

Can wind farms provide more fuel saving if their turbines deliver mechanical energy rather than electricity?

The article by Ben Hargreaves in the October issue of PE on the development of a liquefied air system described a commendable example of original thinking but did not mention how often wind farm production has to be limited because of lack of demand for electricity.

That this may be an elegant solution to a very minor problem is more than hinted at by Bill Hyde his letter in the same issue of PE. The wind energy output figures he quotes underline that under–production rather than over-production is the fundamental problem with wind farms. These have been operating long enough now to show that our land-based wind farms supply, on average, electricity to the grid for 25% of the time. Off-shore farms are rather better but even these give a positive contribution for only 35% of the time.

The question that really needs to be addressed is - can wind farms provide more fuel saving if their turbines deliver mechanical energy rather than electricity?

My letter in the August 2011 issue of PE attempted to show that this alternative approach is feasible and not only offers energy saving at low wind speeds but eliminates the problem of grid instability by transferring the swings in demand to variations of the rate of consumption of fossil fuel.

As a footnote: Paragraph three of the article comments “...the system uses more energy than it produces but makes sense economically...” If reasons can be put forward for questioning the merits of UK system of financing electrical output – this example must be well up the list.

Tom Robertson, Abingdon, Oxon

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