Readers letters
I would ask advocates of energy storage, such as Tony Kaye, three questions:
- What Energy would you propose to store?
- For how long is the store to last?
- What losses/costs are incurred in the storage exercise?
The answers to those questions can be illustrated by what actually happened at 04:00hrs 5th July 2012.
UK’s fossil burn was 16,000MW, nuclear was 8,000MW, with imports of 1,800MW. Our 5,000MW of wind turbines were achieving 2.67% of their full power capacity, 150MW. Total power input to the transmission system was 25,943MW.
Fossil burn could have been reduced by 2,098 MW if we had switched off the pumps that were recharging hydro reservoirs – it takes place every night from 11pm-7am, but not at that rate.
Our annual minimum power demand at a summer dawn last summer was 23,177MW. When our CO2-free generation can do that, regularly, reliably, we can begin to store it. Our wind fleet averages around 27% of its rated power capacity, with low outputs forced upon us, willy nilly.
Should those weather conditions occur in 2020, the wished-for 33,000MW wind fleet would be producing 881MW. What would you do with that extra wind power, store it, or reduce fossil burn?
Europe-wide low wind speeds commonly occur for periods of about a week, occasionally up to three weeks, winter and summer. Storing overnight is one thing...
Energy cannot be created or destroyed, basic physics, but it can be converted from one form to another. Prehistoric solar energy was converted into chemical energy by plants, and by geological processes into coal. Converting that to heat and pressure energy in boilers, and that into mechanical energy in a turbo-generator, and thence into electrical energy uses some of the energy at each conversion.
Researching for the nationalised NSHEB, Professor Peter Payne, showed that pumped storage hydro loses 25% of the energy pumped – water turbulence. The figure can be confirmed by present day figures published by National Grid.
Bill Hyde, Offham, Kent
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