What happens to unused electricity on the National Grid? © Getty Images

What happens to unused electricity on the National Grid?

You can't store large amounts of electricity, so providers have to regulate the supply carefully to meet demands. Otherwise, what happens to the leftovers?

Asked by: Martin Gaff, Bradford

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It’s not possible to store large amounts of electricity so hour by hour, minute by minute, the National Grid performs an elaborate balancing act between supply and demand. Surpluses or deficits on the network manifest themselves as shifts in the mains frequency. The Grid is required to stay within 1 per cent of 50Hz. So, it responds to fluctuations in demand by switching in and out of supply as needed. Some sources offer a quick adjustment, like simply releasing more water into a hydroelectric power plant or cranking up the juice in a gas-powered station. Larger sources like nuclear energy maintain baseline supply, but are slower to turn up or down. Newer dynamic control systems are coming about through domestic devices like refrigerators and air conditioners that detect fluctuations in mains frequency and switch themselves on or off accordingly, thus cumulatively regulating supply.


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