ESO fires up two coal units to deal with heatwave demand

National Grid Electricity System Operator (ESO) instructed Uniper to fire up two back-up coal-fired power units to cope with additional electricity demand during the ongoing heatwave.

One unit generated power for most of Monday (12 June) with the second coming online to help cover the evening peak in demand.

The ESO requested Uniper fired up one of its units at the Ratcliffe-on-Soar plant in Nottingham late on Sunday (11 June). The unit was then turned-on in the Balancing Mechanism, synchronising with the grid shortly before 5.30am and receiving a price of £207/MWh for the duration of its six-hour minimum run-time.

It brought to an end a 46-day coal-free period for Britain’s grid, shy of the nearly 68-day record it set in the summer of 2020.

The ESO also asked Uniper to ready another one of its units at Ratcliffe-on-Soar through the Balancing Mechanism. The unit was ready to synchronise with the grid at 2.25pm and then began generating power for the grid at 5.29pm. Both units continued to provide power to the grid to cover the expected evening peak in demand.

According to the notice on ESO’s Sonar portal, the start up price for both requests was £6,000 per hour.

The indicative start up cost of the first unit is recorded as £21,500, while the indicative start up cost of the unit currently being readied is listed as £39,500.

The de-rated margin forecasted during the evening peak reached a low of 2.3GW for the half-hour period starting at 5pm.

Rajiv Gogna, partner at LCP Delta said that the tight margin “is a level we’re more accustomed to seeing on a cold winter day when demand is typically much higher”.

Gogna added that there were a number of supply-side factors on Monday (12 June) that were likely to be behind the de-rated margin. These include:

• Wind generation is low, at around 2.5GW during the morning. This is forecast to rise to close to 4GW by the evening, but NGESO will be aware that a delay to the timing of this wind increase could make the supply picture for this evening look considerably worse.
• A lot of conventional generators are on outage at the moment. Plants schedule their maintenance outages many months in advance based on prices in the forward market, which are lower over the summer months due to the seasonal demand shape. This leads to lots of generators being on outage at the same time, which can cause a tightness in supply on days when wind is low. This was a contributing factor to some of the price spikes we saw last summer. Over the weekend, both units at Torness nuclear power station began maintenance outages, reducing the available generation by a further 1.3GW.
• The hot weather that we’re currently experiencing also plays a role, as high ambient temperatures reduce the efficiency of thermal generation, meaning that the generators that are available are not able to produce as much as they typically would
• The North Sea Link interconnector, which connects GB with Norway, has limited availability at the moment. This partial outage has removed an additional 700MW of supply from the GB market. GB typically imports power from Norway, particularly during times of low wind generation.

Ratcliffe-on-Soar was one of the coal-fired power stations put on standby to provide extra power by the ESO over the winter as part of the winter contingency plans.

Despite the ESO issuing warnings on several occasions, the coal contingency plants were only required to come online on one occasion in March when EDF’s West Burton A plant in Nottinghamshire began producing power before the coldest night of the year.

EDF and Drax have now begun decommissioning their plants which were kept on standby last winter.

Both operators ruled out the possibility of their units being used again next winter, just hours after National Grid Electricity System Operator (ESO) outlined its intention to begin negotiations for contract extensions.

Uniper has also said that it intends to operate commercially for winter 2023/24 and therefore would also not be in place to extend its contract.

The UK has set targets to close all coal-fired power plants by October 2024.