Q2 2019: Capacity and production statistics

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by Dr Iain Staffell – Imperial College London

This quarter saw new lows for both nuclear and coal power plants, and prices return to 2017 levels.

Nuclear power hit its lowest levels in over a decade, falling by one-fifth on last year to supply just 3.7 GW in mid-June. Several plants were offline for their annual summer maintenance, but Sizewell B suffered an unexpected ammonia leak, and Hunterston B was unable to come back online after further cracks were discovered in its reactor core. A third of the country’s nuclear fleet remained offline for the entire three months of Q2.

Monthly average nuclear output

Coal supplied the smallest share of any generating technology, behind even run-of-river hydro plants, which rarely supply more than one percent of Britain’s electricity.

Wind output was one-fifth higher than this quarter last year, boosted by the offshore fleet. Similarly, imports and exports were both up on last year as the new link to Belgium continues to push up import dependency.

Britain’s electricity supply mix in the second quarter of 2019 

Wholesale power prices fell back to below £40/MWh for the first time in two years as gas prices fell by a third. Ofgem reacted by lowering the cap on retail power bills by £75 per year for a typical household.

Installed capacity and electricity produced by each technology 2 3 

1: About 60% of Britain’s hydro plants are connected to the national grid and reported on here, another 800 MW is ‘embedded’ and thus invisible to us.

2: Other sources give different values because of the types of plant they consider. For example, BEIS Energy Trends records an additional 0.7 GW of hydro, 0.6 GW of biomass and 3 GW of waste-to-energy plants. These plants and their 
output are not visible to the electricity transmission system and so cannot be reported on here.

3: We include an estimate of the installed capacity of smaller storage devices which are not monitored by the electricity market operator. Britain’s storage capacity is made up of 2.9 GW of pumped hydro storage, 0.6 GW of lithium-ion batteries, 0.4 GW of flywheels and 0.3 GW of compressed air.

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

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