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BLOG: The electricity system's balancing act, and why we need it

Posted on 08/01/2019 by Nick Sharpe

Today's electricty system is a complex piece of engineering which touches the lives of everyone in the country.

Paying for that system means making choices. Here we try to explain, with some help from National Grid, why all generators are sometimes compensated for not producing electricty.


Demand for electricity from consumers isn’t constant.

Neither is supply from variable sources like wind power, hydro or solar, or indeed from traditional power stations, which can suffer sudden breakdowns or require maintenance.

The average UK fossil-fuel power station is more than 30 years old.

We need to replace these plants for two reasons: to ensure we have enough electricity in future and to reduce the carbon emissions which are causing climate change.

Our electricity transmission system was built more than half a century ago, so requires upgrades in order to cope with new ways of generating and using power.

A constraint arises when power cannot be transmitted to where it is needed, usually due to congestion at one or more points on the transmission network.

When this happens, National Grid must take action to ‘balance’ the network. This is similar, the organisation explains, to:

"...occasionally using traffic lights to manage the flow of cars joining a motorway during a busy period. It wouldn’t be economic or sensible to build another parallel motorway so that there was never a traffic jam.

"In Great Britain, market generators pay to have firm access to the transmission system 24 hours a day, seven days a week, so they can choose when and how much to generate. When a generator cannot fully use the access paid for, they receive compensation in the form of a constraint payment."

In future smart systems will help balance any mismatch in supply and demand.

They'll allow us to make better use of existing overhead lines rather than installing new ones, or ensure electric vehicles charge during when demand is low or electricity plentiful.

Scotland is playing a leading role in the development of these systems, but we’re still at the very start of seeing them make an impact on the energy system – an impact which will help us use more of the clean power generated by renewables, saving money for consumers.

Nick Sharpe

Director of Communications