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How Reliable Are Britain’s Wind Farms?

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Britain’s energy system must account for the undeniable fact that wind farm output will regularly go close to zero. 

According to the Telegraph website, Drax (the owner of Britain’s largest biomass power plant) has attacked wind and solar power for their lack of reliability.

The Telegraph reports:

Dorothy Thompson, Drax chief executive, said the UK’s wind and solar farms were “increasing the instability of the grid”, with “mounting” cost implications, citing forecasts suggesting the bill for balancing supply and demand would rise from £1bn this year to £2bn by 2020.

Yet “aggregate wind farm and solar output in the UK can be expected to fall below 1pc of total electricity production with reasonable regularity”, she argued.

 The industry lobby group Renewables UK, naturally, wasn’t too happy:

The comments prompted an angry response from wind industry body RenewableUK, which said Drax was “wrong to accuse wind of increasing instability on the grid” and “misleading to claim that wind output regularly falls to low levels”.

Now, this sounds like a factual matter worth looking at quantitatively. Does wind output regularly fall to low levels?

Given that Drax appear to have got their information about the reliability of wind farms from something I wroteperhaps I am in a position to answer.

Drax claims that wind farm output is expected to fall below 1% of electricity production with reasonable regularity. This is not what I said.

Instead I showed that aggregate wind farm output should be expected to fall below 1% of total installed capacity. This is actually a much stronger claim.

In effect, wind farms can be relied on for absolutely zero power. When electricity demand peaks we must be ready for wind farms to be producing more or less nothing. This is a simple fact, and no amount of hand waving and vague language from lobby groups can get around it. (Of course technological innovation in energy storage might change this, but that’s another story.)

The fact that wind farms can produce almost zero power is regularly denied. This is normally done by waving of hands. “If it’s not windy one place, it will be windy elsewhere”. Not so.

To see this consider what happened on the 16th June 2013.

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