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Putting some gas in the net zero tank

To avoid the ever-growing impacts of climate change, we need to decarbonise our economies as rapidly as possible.

Shifting to zero-carbon power systems will get us a long way there, and although the technologies needed do exist, unfortunately many of them remain prohibitively costly to deploy at scale.

Overly ambitious targets and timelines risk heaping costs on consumers, triggering a political backlash that could delay the entire process.

This delicate balance between climate commitments and cost was thrown into the spotlight by the recent news that the UK government wants new gas-fired power plants to be built. It argues that these plants are vital to avoid blackouts in an electricity system dominated by intermittent renewable energy capacity.

Environmental groups instead argue that this represents the latest roll-back of climate commitments by a government running scared of right-wing climate sceptics and anti-regulation ideologues. They say that the right mix of subsidies and incentives can create a zero-carbon power system without the need for more fossil generation.

As is often the case, both sides are right – up to a point. The current prime minister is markedly less enthusiastic about the net-zero transition, slowing or abandoning a number of climate policies introduced by his predecessors. But the awkward reality is that, without incurring socially and politically untenable costs, we will need back-up fossil generation for some years to come. The challenge is to make sure that that generation has as little climate impact as possible, for as short a time as possible.

The problem

The UK has made great strides in decarbonising its power system. Last year, renewables supplied 47.1% of the UK’s power, up from just 2% in 1991 and 15% in 2013. Zero-carbon nuclear power supplied 13%. Of the remainder, natural gas supplied 31%, coal around 1%, while 7% was imported from the continent.

However, we have a long way to go to meet the government’s goal of 95% low-carbon power by 2030, and a fully decarbonised grid by 2035. The Labour Party’s timeline is even more ambitious: it wants to deliver a “zero-carbon electricity system by 2030”.

There is considerable devil in the detail of these pledges. But fundamental to both is a massive increase in wind and solar generation. The challenge here is that wind and solar are intermittent – and the nightmare for electricity system operators is what Germans call Dunkelflaute. This describes windless, overcast and cold periods when renewable energy generation plummets – and the lights risk going out.

Solutions on the horizon

There are a number of solutions to the problem. One is to increase the size of the system, to provide the capacity to transport large volumes of clean power from where the wind is blowing or the sun shining. Considerable investment in transmission capacity is underway – across Europe, 23 GW of interconnector capacity is expected to be added in coming years to the existing 93 GW.

However, this investment is trailing behind the 64 GW the grid operators’ association says is needed by 2030. And, even if transmission capacity met demand, despatching power across large distances results in losses that substantially increase the cost of that power.

The cheapest megawatt hour of power is the one that isn’t needed. Reducing peak demand for power – through better insulation, more efficient equipment, or by shifting demand from periods of high demand to periods of excess supply – can dramatically reduce overall system costs.

Here, the UK has made less progress than it should have done, with repeated failures to properly incentivise domestic insulation and half-hearted efforts to encourage demand-side management technologies and practices. In addition, overall power demand will inevitably increase as we electrify transport, heating and grow power use in the production of hydrogen and the expansion of data centres.

The ultimate goal is to match intermittent renewable energy generation with long-duration storage. However, for all the dramatic falls in the cost of short-duration battery storage, and the increase in its capacity, we have limited cost effective ability to store power for more than eight hours with lithium-ion, and the cost of doing so with this technology remains very high. There are solutions on the horizon, such as Redox flow and Metal-air batteries, which promise to allow seasonal storage of excess power, but their commercialisation is years off.

Getting from here to there – without breaking the bank

We need to build a bridge to a future when sufficient long-duration storage and system flexibility allows us to drive carbon emissions out of the power system. That will involve gas-fired generation which, over time, is fitted with carbon capture and storage (CCS) technology.

This is not a costless option. Energy research firm Aurora Energy Research calculates that 5 GW of back-up capacity will be needed, at a cost of £5 billion – putting an average of £178 on each household’s annual energy bill for a decade. This bill will increase when gas-fired generators are required to capture and store their carbon.

But pursuing a limited increase in gas-fired generation, with requirements that any such capacity is CCS-ready, is likely to offer the best balance between cost and ambition. Simultaneously, this government – and whichever party wins the next election – must much more aggressively pull all the levels at its disposal to encourage investment in transmission, demand-side management and energy storage. It should ensure that the UK’s carbon price recovers, helping to underpin the economics of CCS.

The case for urgent climate action is irrefutable. But that action can’t come at a cost or a pace that consumers and voters find unacceptable.