Over Easter the UK set a new record for coal-free power, with the country running for more than 90 hours powered by gas, nuclear, hydro, renewables and imports.

The milestone, which beat the 76 hours set last April, comes as the government prepares to ditch coal completely by 2025, and aims for wind generation to provide a third of the country’s electricity by 2030.

It’s a remarkable shift for a country that was once among the world’s biggest coal consumers but is now considered a case study among developed economies in how to transition to cleaner power.

Moreover, the country is poised to toughen its greenhouse gas emissions targets, a move that would have dramatic implications for the power sector.

Next week the Committee on Climate Change, a government advisory panel, will present its opinion on whether the UK should adopt a net zero carbon target for 2050 as part of its climate change goals, compared with the current target of an 80 per cent reduction from 1990 levels.

If the government adopts tougher emissions goals, and in the past it has followed the committee’s advice, further decarbonisation of the power sector will be central to meeting the new target, as cleaner power has been the single biggest factor behind the UK’s falling emissions during the past decade.

Since 1990, the UK has cut greenhouse gas emissions by 43 per cent and most of the decline has come from cleaner power. Emissions from the sector have fallen by 65 per cent in the past 29 years.

“The general consensus is that power is the easier bit to decarbonise,” said Richard Howard, research director at Aurora Energy, a consultancy. “To hit the 80 per cent emissions reduction target, power will have to exceed that and get very close to zero, because some of the other sectors will be more challenging, like aviation, agriculture, and heating.”

This is demonstrated by the fact that, despite the progress in the power sector, the country is not on track to achieve its existing decarbonisation targets, which run until 2032.

Ahead of the announcement, National Grid, the listed company responsible for balancing power supply with demand, has already begun planning for an electricity system capable of operating with net zero carbon emissions. This would be able to incorporate much higher levels of intermittent power from wind and solar than the system today.

Julian Leslie, head of national control at the National Grid Electricity System Operator, an independent unit of National Grid, said shifting to a net zero carbon system meant “fundamentally changing the way we think about electricity”.

This would include more energy storage, different energy use patterns, and new technologies to keep the grid stable.

It would require approximately quadrupling the amount of energy storage such as batteries connected to the grid, to help balance out the irregular power supply from renewables and to provide back-up if a large power plant fails, he said.

National Grid estimates it would need about 1.3GW of energy storage, equivalent to the Sizewell nuclear plant, to safely operate an electricity system with net zero carbon emissions.

Another change needed to operate a net zero carbon power system is to be able to control the demand for electricity, with a centralised system that links up to thermostats and factories across the country.

“At the moment we dispatch generation to meet demand, but at some point we need to switch that around, to dispatch demand to meet generation,” said Mr Leslie. That could include an automated system that would use incentives to shift the timing of factory operations or household appliances — such as running dishwashers — to times of high winds.

One big challenge is that several UK nuclear power plants are set to retire in the next decade, and plans for new plants have faced delays or cancellations.

With fewer sources of consistent “baseload” power and more intermittent power from offshore wind, the system will require more flexible sources. These could include gas plants or imports, that can feed in when renewables sources are low.

A low-carbon system also needs new technologies to maintain the stability of the electrical grid and the frequency of the voltage. So while renewables costs have been falling, the cost of implementing a zero-carbon electricity system was still likely to run into the billions of dollars a year

A 2015 estimate from the Committee on Climate Change found it would cost at least £8bn per year throughout the 2020s, to achieve a level of decarbonisation in the power sector that is compatible with the UK’s existing carbon targets. It is expected to present new cost estimates next week that will reflect the falling cost of renewables, along with its recommendation for a new emissions reduction target.

Mr Leslie said a zero-carbon grid would be cheaper to operate and maintain after the initial improvements were made, but the National Grid has not yet estimated how much the upfront investment cost would be.

Alex Kazaglis, principal energy economist at consultancy Vivid Economics, and formerly at the CCC, said that while it was “incredibly challenging” to operate a zero-carbon electricity system, the cost should not be prohibitive if, as is usually the case, distributed across consumers.

“The thing about distribution networks is, once you spread that cost across consumers it ends up being quite small,” he said. “It’s a big cost in billions but small per kilowatt hour,” he said.


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