Heat: detangling decarbonisation

"Fretting about implementation challenges before assessing decarbonisation potential is putting the cart before the horse"

If I asked you: should we get the train or drive? Take the motorway or the B-roads? Will the traffic be bad? You’d probably reply: well, where is it you’re going exactly?

Because trying to plan a journey without an idea of destination is doomed to fail. Yet that’s precisely where we’ve found ourselves in the debate around decarbonising heat in the UK.

2050 is only 32 years away, by which time we need 100 per cent, total decarbonisation of heat to meet our legally and morally binding climate commitments. The two frontrunner “big ideas” are electrification and greening the gas network with hydrogen. But we’ve jumped immediately to squabbles about costs and technical challenges. We’re fretting about traffic and lane closures before deciding where we’re headed.

Step one is to figure out which option offers the most credible path to complete decarbonisation (with immediate effect). Step two is to address the challenges. Who picks where they’re going because the roads are clear?

The cart pulling the horse

Fretting about implementation challenges before assessing decarbonisation potential is putting the cart before the horse. How can we reverse that?

First, we need to ask which technologies can deliver truly zero carbon heat? Secondly, which can start to do so now? To the first, we can answer electrified heat or electrolysis-generated hydrogen powered by zero-carbon generation.

To the second though, the only answer is electrification, where technologies such as air and ground source heat pumps are consistently improving. They rely on electricity to generate heat – recognisably the one area where we have achieved significant success in decarbonisation. Average grid carbon intensity stood at an estimated 254 tonnes of carbon emitted per GWh produced by 2016, down from 456 in 2010.

Electrolysis, by contrast, is at least a generation away at a commercially viable scale. Nor will it appear spontaneously once the technology is ready: most likely it will only take off if there is already an extensive hydrogen network, meaning in the meantime we’d need to rely on steam methane reforming (SMR), which releases carbon which would need to be captured by carbon capture and sequestration (CCS). That technology doesn’t currently exist at the required commercial scale either.

We can’t wait a generation to start serious decarbonisation of heat; both options could take 20-30 years to see these technologies deployed at the necessary scale.

Rumours of impossibility, greatly exaggerated

So, electrification offers the only currently credible path to zero carbon heating. With that as a starting point – the horse firmly in front of the cart – but now it’s time to looks at the challenges.

There is one overarching argument against electrification of heat that is put forward time and time again: that peak heat demand in the UK is roughly six times peak power demand, and that the volume of extra generation required and the strain on the distribution grid makes it unfeasible.

But that “six times” argument doesn’t stack up.

First, the UK has been lazy in controlling heat. Cheap, plentiful North Sea gas has seen the UK trundle along with some of the most inefficient building stock in Europe. There are big, easy wins to be had by tightening building regulations to make our homes and businesses less wasteful.

Then, look at the opportunity presented by smart heating controls such as Hive and Nest. These will help to reduce peak demand and, coupled with better insulated homes, we could see that “six times” gap start to narrow pretty quickly.

Having reduced heating demand, we can start to think about how electrification fares at meeting what remains. Usually we use gas demand as a proxy, so interlinked they are. But gas is never 100 per cent efficient, there is always wasted energy. So, we may well find that final energy demand is a little less dramatic than we think.

Second, electrification and thermal storage technologies open up possibilities to time-shift demand, smoothing the “six times” peaks. This could be as simple as filling a hot water tank when power is plentiful overnight, or as advanced as using geo-exchange to store heat in the ground over summer to be used in winter.

So, let’s start right now by getting a better understanding of actual heat demand and reducing it – that first part of the journey is the same regardless of the destination. Then let’s get clear about where we’re headed and start planning how to get there – not the other way around. It’s clear to me that electrification is the most viable route to truly zero-carbon heat and has the advantage that we have the proven technology to start right now.

There are legitimate challenges – notably around the peakiness argument – but they have been shown to be overblown. In any case though, we need to detangle our thinking and start making decisions now. Climate change won’t wait. So, where to?