Heated debate: Why the big spat over decarbonising homes?

Wind power entrepreneur Dale Vince has lobbed a green grenade into government plans to decarbonise the way we heat our homes by launching a campaign in the Daily Express – where he is now a regular columnist – to “save Britain’s boilers”.

Entrepreneur Dale Vince. Photograph: Andrew Vaughan/Getty Images

Drawing on reports by the Committee on Climate Change (CCC) – including Next Steps for UK Heat Policy and the Sixth Carbon Budget – prime minister Boris Johnson pledged last year, in his 10-Point Plan for a Green Industrial Revolution, that by 2028, we would be installing 600,000 heat pumps every year. Powered by renewable electricity, this would help push the UK towards 2050’s net zero carbon emissions target. 

But Vince claims that ditching tens of millions of boilers is unnecessary and hugely expensive. The UK could produce sufficient quantities of biomethane from grass grown on farmland, he argues, and a new plant, which takes this grass and uses biodigesting technology to create methane, will come on stream near Reading next year.

But carbon policy experts were quick to pour dry ice on Vince’s plans. On Twitter, Tim Lord, a senior fellow at the Tony Blair Institute for Global Change, said there was no clarity about how much land would be required to heat 14 million homes – half the UK’s housing stock – as proposed by Vince. It appeared to range somewhere between 1.8 and 4.2 million hectares, which equates to between roughly 10% and nearly a quarter of the total area of farmland.

Vince declined to be interviewed by ENDS for this article, but he later suggested on Facebook that the actual requirement was around 3.6 million hectares – still a whopping 20% of farmland. 

Jenny Hill, the CCC’s head of buildings and international action, said that in their view, this was not the most environmentally friendly or efficient way to reduce carbon emissions.

“I think he is ignoring the bigger picture on a couple of points,” Hill told ENDS. “First of all, there are the implications for land and the natural environment, and secondly, this broader energy systems perspective of what is the most effective use of biomass and the fact that net zero means really limiting CO2 emissions into the atmosphere. If you use biomethane, you are still burning CH4, and that produces CO2.”

In the 6th Carbon Budget, the CCC does envisage a role for so-called energy crops in decarbonising the British economy, but these would be Miscanthus or elephant grass and short-rotation coppice. They propose the planting of approximately between 10-60,000 hectares a year, starting in the mid 2020s and carrying on throughout the 2030s and 2040s, leading to a total area of 0.2-1.4 million hectares by 2050, with a central estimate of 0.7 million hectares. 

“The key point about grassland is preserving carbon stocks,” Hill said. In its report, the CCC found that to maximise carbon sequestration you could only plant energy crops on arable or crop land, and not on permanent pastures, because this “could increase net emissions with on-going soil carbon losses exceeding the carbon sequestered by the energy crop.” 

Other aspects of Vince’s arguments in favour of a massive scaling up of biomethane production also received short shrift. For example, Vince claimed that installing heat pumps across the country would require a tripling of our electricity capacity and cost a combined total of some £300bn. 

Again, this doesn’t tally with what’s in the 6th Carbon Budget, Hill said. “We talk about a doubling of electricity generation over all, and that includes additional demands from industry and electrification of transport,” she pointed out. “Tripling capacity would suggest very inefficient heat pumps – it wouldn't be worth doing it if that was the case.”

One aspect of the CCC’s proposal for decarbonising the heating of homes and businesses that Vince appears to have overlooked is that it doesn’t involve putting them in every home. The plan, for example, suggests that up to five million homes could be served by large-scale water and sewage source heat pumps, rather than having individual pumps in every house, which would be “pretty cost-effective” for cities, Hill argued. 

Vince is right about one thing – there may be an issue with persuading consumers to accept heat pumps as the best way forward. The Next Steps report warned that the low-carbon options, such as heat pumps, would not be attractive to the public without subsidies. 

But Hill said heat pumps are “by far the most efficient way to use renewables to generate heat” and that with the right support and clear standards, it should be possible to drive down costs and make them a “mass market solution”. 

Going down the biomethane route – which doesn’t involve any need to replace or even upgrade boilers – was definitely “an easier option from a consumer perspective,” Hill conceded, but added that it was only likely to be sustainable in quantities sufficient to heat two million homes. 

So whatever Dale Vince’s aspirations, it appears that Britain’s gas boilers will need to be largely replaced over the next 20 to 30 years if it is to hit the carbon emissions target.