CCC: UK must act now to secure zero-carbon heat by 2050

§ Challenge

The UK is legally bound to cut its emissions 80% below 1990 levels by 2050. At some point, in order to comply with the Paris Agreement, it will need to reach net-zero emissions. (See Carbon Brief coverage of what the Paris Agreement means for the UK’s climate targets).

The 2050 limit only leaves space for the hardest-to-eliminate emissions, such as those from aviation, industry and farming. As a result, UK heat must be virtually decarbonised by 2050.

Today, the heating and hot water needs of UK buildings account for 40% of energy use and 20% of greenhouse gas emissions. “It will be necessary to largely eliminate these emissions by around 2050,” the CCC says.

Adding to the problem is the strongly seasonal need for heat energy. UK electricity demand varies between lows of around 30 gigawatts (GW) and highs of a little more than 50GW. In contrast, heat energy demand ranges from lows of 25GW in summer to peaks of 300-350GW in winter.

Zero-carbon alternatives to the UK’s predominantly gas-fired UK heating infrastructure would, therefore, need to be able to meet peak demand some five or six times higher than peak power demand. This would be eased if there were a way to store zero-carbon energy across seasons.

The challenge of decarbonising heat is amplified by the lack of clear technological solutions.

At a briefing for journalists, Lord Deben, CCC chair said:

§ Options

The CCC identifies three main options for decarbonising heat supplies. The first is low-carbon district heat networks, most suitable for densely populated cities. These can use waste heat, large-scale heat pumps that draw warmth from rivers and potentially hydrogen, the CCC says.

The government has earmarked £320m for investment in heat networks out to 2020. The level of ambition this represents would have to be scaled up in the 2020s, the CCC notes. Building heat networks can be highly disruptive because it requires pipes in the ground.

The second option is heat pumps powered with zero-carbon electricity. Enthusiasm for heat pumps is low in the UK, even though they are widely used in many other countries, the CCC says. A recent report for thinktank Policy Exchange said heat pumps were costly and disruptive to install.

Installations are running at around 20,000 a year. To decarbonise heat using heat pumps alone, this figure would need to rise 50-fold to 1 million a year from the mid-2030s, the CCC says. It would also necessitate heavy investment in additional zero-carbon electricity generating capacity.

The third option is to repurpose the existing gas grid with hydrogen. This would involve less disruptive changes for households but would necessitate a zero carbon source of hydrogen, with uncertain costs.

Hydrogen could be produced from gas, alongside carbon capture and storage (CCS), as advocated by the UK shale gas industry. “Before a decision to proceed with hydrogen, it would be essential that CCS is under active development in the UK,” the CCC says.

Alternatively, hydrogen could come from electrically-driven hydrolysis, though the CCC notes that this would once again impose a heavy burden on electricity supplies.

All of these options for low-carbon heat are imperfect, as the grid below shows. In a paper on the future of energy systems governance, energy regulator Ofgem says:

“Conversion of heating to either district heat or hydrogen will require coordination and restrictions on choice – it will probably not be possible for individual households to choose whether or not to join the new network.”

§ Action

These challenges are daunting and it will take time to develop new strategies, governance arrangements and pilot schemes so as to evaluate the costs and benefits of each option.

The CCC says:

It adds:

Meanwhile, there is much that must be done in the interim in order to keep on track with the UK’s climate goals, the CCC says. A 2016 report on heat from Imperial College says:

The government’s ambition to install a million energy efficiency measures during this parliament is completely out of step with the requirements set out by the CCC. It says that seven million lofts and cavity walls should be insulated by 2030, at a rate some 2.5-fold faster than current efforts.

One option would be to extend existing regulations on minimum energy efficiency requirements for private rented accommodation. A report on decarbonising heat from the UK Association for the Conservation of Energy says government “must bite the bullet” by setting mandatory minimum energy efficiency standards for all buildings, at the point of sale.

The CCC’s report floats the idea of standards for the emissions performance of buildings that would tighten over time but stops short of recommending regulation. Lord Deben told journalists:

§ Conclusion

Decarbonising heat will be a vital piece of the puzzle if the UK is to meet its climate targets and comply with the Paris Agreement. It’s a daunting challenge with a range of possible solutions.

All of the options present problems, from disruptive infrastructure or home retrofit needs to potentially high costs or requirements for much more extensive roll-out of zero-carbon power.

Yet the time needed to resolve some of these issues must not be wasted, the CCC says, since many investments make sense now regardless of the path we choose in future. Chief among those is energy efficiency, without which the already steep challenge of heat would become harder still.