UK day-ahead power prices soared to more than a five-month high on Monday despite forecasts of high wind power generation, on market jitters due to an unexpected nuclear plant outage earlier in the day, sources said.
Price of baseload power for Tuesday delivery was last trading at GBP41.50/MWh, up GBP2.25 from Friday's assessment for Monday, while the Tuesday peakload contract rose a steep GBP6.15 to GBP49/MWh before the 11am London time market close.
Both the base and peak day-ahead contracts hit their highest since February 24 when they were assessed at GBP42/MWh and GBP51.25/MWh respectively, S&P Global Platts data showed.
At 12:36 am BST, a "failure" reduced the UK's 504 MW Hinkley Point B nuclear unit 7 reactor 3 capacity to zero, operator EDF Energy said on its REMIT website. National Grid said the tripped unit is expected to return to the grid on August 7.
This has decreased available nuclear capacity to 7.1 GW on Tuesday, down from Monday's forecast of nearly 7.8 GW, the Grid data showed. Also, gas-fired plant availability is expected to slide a touch to 21.7 GW on Tuesday, compared with 21.9 GW on Monday.
However, further on the supply side, wind power output is likely to peak at above 3 GW on Tuesday, more than double Monday's forecast of 1.3 GW, the Grid said.
At midday Monday, Dutch and French power links were running at full capacity, sending 1 GW and 2 GW of electricity respectively into the UK, with gas-fired power plants offsetting curtailed wind output.
Gas plants generated 18.3 GW of power, whereas UK wind farms produced less than 500 MW of power at midday Monday. Coal-fired power stations produced 1.7 GW of electricity, while nuclear output reached 7.5 GW, the Grid data showed.
