Big falls in construction output were a factor when the UK was last in recession in the first half of 2012.

BBC: Cranes in London

Assuming a rated capacity per turbine of 5 MW, and a capacity factor (actual output) of 30%, we have 1.5 MW for each.

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If it had not been for that special factor pulling down output in the second quarter, it looks as though the UK's official GDP numbers would have shown the economy to be growing since the spring.

BBC: A special recovery

The second factor is the explosion in gas output in the U.S. caused by the shale gas boom.

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In the energy complex, geopolitical risk tends to be a prevalent supply shock factor, as I recently have observed with Libyan crude oil output.

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