How our electricity supply depends on the weather

by Dirk Cannon                                          Department of Meteorology homepage

“It was one of those March days when the sun shines hot and the wind blows cold: when it is summer in the light, and winter in the shade.”

Charles Dickens ponders our changeable weather in Great Expectations

We use different amounts of electricity from summer to winter; from daytime to night-time; from just before EastEnders finishes to just afterwards, at which point thousands of people switch the kettle on. Because electricity can’t be efficiently stored, this means our power stations have to be turned up and down all the time to respond to changes in demand. On a cold, stormy winter’s evening we might cling to our mugs of tea, watching TV with the heating and lights on, using lots of electricity; but on a warm summer’s day we might sit outside reading a book, using no electricity at all. Whatever we do, National Grid (who operate the electricity network) make sure there is just enough electricity generated by power stations to match our needs.

So our electricity supply has always changed with the weather, but as renewable energy sources have emerged the picture has become even more complicated. In January this year a record 14% of the UK’s demand for electricity was met by wind farms, enough to power 8.7 million homes. As storms come and go and the wind speed goes up and down, so does the electricity generated by wind farms. If these ups and downs are accurately forecast in advance, then National Grid can easily plan for the changes in power output in the same way they plan for other expected changes in generation or demand. On the other hand, if the changes in wind power output are poorly forecast, they have to be compensated by other power stations at very short notice. These last-minute decisions can cost National Grid (and ultimately all of us) a lot of money. It’s not surprising then that more accurate wind power forecasts, as well as more intelligent use of existing forecast information, is recognised as an integral part of plans to radically reduce our reliance on fossil fuels and reduce unnecessary future rises in our energy bills.

2015 03 25 Dirk Cannon Fig 1 new How changeable is UK wind power? How extreme can wind power swings get? How well are extreme events forecast? These are just some of questions we are addressing in our project, using past measurements, state-of-the-art reconstructions of the UK’s weather and the latest and greatest global weather forecasts. We are also working closely with National Grid engineers to help them use the information currently available in state-of-the-art weather forecasts more effectively and reduce the costs associated with forecast uncertainty.

More information about our project

Find out more about the other research going on in the Energy-Meteorology Group here at the University of Reading.

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