Q1 2018: Who helped and hindered the system?

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by Dr Iain Staffell – Imperial College London 

How much can Britain rely on its neighbours in times of stress? Would the lights have gone out if it were not for coal power? 

The Electric Insights data helps us understand who helped, and hindered, the power system during the extreme weather.

The power flowing over Britain’s links to other countries are shown below. Britain had been largely importing from France all year, but began exporting solidly through the 27th and 28th of February. France was also experiencing severe cold, and a greater share of French homes use electric heating. On the two coldest days, Britain exported at an average of 0.9 GW (28th, –3.6°C) and then imported an average of 1.2 GW (1st, –3.8°C). 

Britain imported steadily from the Netherlands, and traded power back and forth with Ireland1 to help balance both systems. On March 3rd the East-West link between North Wales and Dublin was taken offline for (unrelated) maintenance. 

The output from coal during this period dwarfed these exchanges with our neighbours (chart below). The cold spell saw the return of ‘king coal’, which reverted to being a baseload generator. Coal operated solidly day and night for a week as high gas prices made it briefly more economical. 

The system would likely have coped without this coal. 12–19 GW of spare gas capacity was available, albeit at a high price. While this means we were not short of capacity, if the extra coal output had been met by gas, it would have consumed around an extra 6 TWh of fuel – more than was available in storage by the end of March. 

More coal units are going offline as Britain moves to a complete phase-out by 2025, meaning this source of backup and flexibility will not be available for long. 

Hourly electricity supply from Britain’s interconnectors (top) and coal power stations (bottom) over the quarter 

  1. This refers to the island of Ireland as both Northern Ireland and the Republic of Ireland are on a separate electricity system to the National Grid. 

Authors: Dr Iain StaffellProfessor Richard GreenDr Rob Gross and Professor Tim Green.

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