UK must plan for hotter summers without coal

The UK is going to have to find a solution to deal with increased energy demand during the summer, energy retailers, analysts and climate change activists have warned.

It comes after 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.

In total, the ESO has so far spent in excess of £60,000 for coal-fired power stations to fire up this week.

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 on Monday (12 June).

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 began generating power for the grid at 5.29pm on Monday (12 June). Both units continued to provide power to the grid to cover the evening peak in demand and restarted generation on Tuesday (13 June) morning.

The spike in energy demand has been widely attributed to an increased use of air conditioning units and electric fans.

However, Aurora Energy Research senior associate Tom Smout added that other cooling appliances such as fridges and computer fans “also have to work so much harder during a heatwave and therefore use more energy”.

Smout added that using coal in a heatwave as a back-up contingency “makes sense as it is much more reliable than gas”.

“Gas turbines are quite complex pieces of engineering and they don’t always cope well with extreme heat, whereas coal plants are far more reliable when it is really hot,” he explained.

However, Smout stressed that “we have to have a solution that is not coal in the very near future”, with the UK planning to close all coal-fired power plants by October 2024.

He added: “But for now it makes sense from a price point and reliability. It is also only a small amount of emissions as it is only used in emergencies as a back-up.”

On Monday 12 June coal generated 5.72GWh, which equates to 0.84% of Great Britain’s total energy generation for the day.

The coal units provided power for 12 consecutive hours on Monday, before coming offline shortly after midnight. They then restarted generation at 7am on Tuesday morning after a six hour hiatus. The units were taken offline but remained on standby from around 1pm on Tuesday afternoon. In total, the units generated 2.33GWh on Tuesday, equivalent to 0.35% of the country’s overall generation.

For most of Monday, the ESO operated with a de-rated margin of around 4GW. It reached a low of 2.3GW for the half-hour period starting at 5pm on Monday afternoon.

Smout explained that ideally the ESO would want that margin to be between 10GW and 15GW, adding that anything below 5GW “is when extreme events can occur”.

Smout added that “it is likely that demand in the summer will increase in Great Britain during the coming years” due to climate change.

He added that the planned rollout of heat pumps will also increase demand in the summer as most can also operate as air conditioning units.

However, he said “planning for hotter sunnier days is easier than starting from scratch in a windy location, for example”.

He added: “Solar is cheaper, there are less planning hurdles. The only thing holding back solar in the UK at the moment is demand. It is much easier to plan for hotter climates over windy ones.”

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”.

He added that there were a number of supply-side factors that were likely to be behind the de-rated margin. These include:

• 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.

Smout said that better planning of infrastructure upgrades would help ensure there was enough capacity on the grid all year round. He added that plant and interconnector operators are currently incentivised to stay online during the winter and carry out maintenance or refuelling in the summer months, which means that “even if demand is not peaking, capacity constraints are usually there”.

Octopus Energy has also called for reforms to ensure that the UK ends its reliance on coal as a back-up source of power. However, the retailer believes that the solution to the problem already exists and has called on the ESO to use customer flexibility as a permanent solution to end the reliance on back-up coal generators.

In a white paper, the retailer claims that extending the Demand Flexibility Service (DFS) to all 17.3 million smart meter customers would instantly end the need for back-up coal plants.

Meanwhile, Jess Ralston, head of energy at the Energy and Climate Intelligence Unit (ECIU), added: “Until we reach net zero emissions, the world will continue to get hotter and heatwaves like the UK’s 40.3C one from last year will become more frequent. This is bad news for vulnerable people, like the elderly, but it’s also going to put added strain on our power system to try to keep them and others cool.

“Coal is playing a bit-part role in the electricity grid, and both here and in Europe its use is plummeting, partly because of its high emissions. With more offshore wind, and solar particularly in the summertime, coal’s back-up role will become redundant with smarter markets combined with batteries and other storage technologies.”

Greenpeace has also called for more diverse forms of generation while urging government to support the rollout of energy efficiency measures, in particular insulation, to ensure homes are able to better meet climate change demands.

Ami McCarthy, Greenpeace UK’s political campaigner, said: “If our homes were properly insulated, they’d keep us cool in the summer as well as warm in the winter, plus some heat pumps can cool as well as heat homes.

“The government must get to work and upgrade our energy grid. In summer, we should be turning to solar power, yet we currently have renewable energy going to waste because our grid cannot transmit the power, and hundreds of renewables projects which are on hold because they can’t get connected.”

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.

Resilience in action is one of the themes at Utility Week Forum. To find out more click here.