WHEN confronted with the scandalous cost of constraint payments to windfarms when their generation is surplus to requirement, the wind industry correctly points out that all generation technologies are constrained off from time to time and are all compensated for their losses by National Grid (NG). This is a brief explanation why wind generation constraint payments are not the same as other generation constraint payments. National Grid (NG) balances supply and demand for electrical power. NG does the fine tuning second by second by asking for more or less generation and either paying for it or compensating for a generator’s lost sale of electricity when it is asked to shut down.

Constrained-off oil, coal or gas generators then give NG a rebate for the saving on fuel. Constrained-off wind generators lose the sale of electricity but also lose their subsidy worth about as much again as the cost of the electricity and need to be compensated for this loss. However, that makes wind about twice as expensive as other technologies to constrain off and NG also has to balance its books so NG never chooses voluntarily to constrain off wind for routine balancing of the grid. In practice, wind is only constrained off if NG has to deal with an excess of generation and has exhausted all cheaper options.

This puts the wind generators in a very favourable negotiating position because NG cannot allow excess wind generation to destabilise the system. The outcome is always a payment to the wind generator well in excess of his losses. This form of doing business is normally referred to as ransom or blackmail, but it is legitimate. Note that when oil coal or gas is constrained off because of rising wind, we pay for these constraint costs as well as the twice-as-expensive wind generated electricity.

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Stuart Young,

The Larches, Laggan Bridge, Newtonmore.

YOUR front-page headline on Tuesday (“Crackdown on energy bills to save consumers £100 per year”, The Herald, May 9) suggests that no one in the media has learned from Brexit promises, because this is up there with the promise of £350 million per week for the NHS.

Those of us who have “shopped around” are already on the best deals available and only those on high tariffs are going to save anything at all. Of course, I am delighted for the consumers that will benefit from this “promise”, but it would have helped all of us if Theresa May had promised to rein in energy companies that apply such huge increases to their tariffs using just about any premise they feel will fit the bill (pun intended).

Francis Deigman,

12 Broomlands Way,

Erskine.