Hydrogen and the future of heating

As Britain aims to reach zero carbon by 2050, there are a number of big priorities on the to-do list. The most high profile is to switch all electricity production away from fossil fuels. Another is to eliminate petrol and diesel from the transport system. Then there’s the third big ticket item: deliver low carbon heating.

As things currently stand, over a third of the UK’s carbon emissions come from heat. It’s a big and varied category that includes cooking, hot water, heat for industrial processes such as steel production, and domestic heating. Today I want to look at domestic heating in particular, and the role that hydrogen could play. (It’s post number 3 in a series on hydrogen).

Heating our homes accounts for around 15% of carbon emissions in the UK. That’s a big enough slice that we don’t reach zero carbon without some serious work on the subject. As I’ve often argued, the place to start is insulation, and reducing the need to heat homes in the first place. New homes should be build to zero carbon standard, and older homes retrofitted. I’ve been working on this with my own house. Once demand has been reduced through efficiency, heat can be electrified – through heat pumps in particular.

Hydrogen offers another possibility. Most British homes are heated with gas – around 85%. There is an established gas grid, a connection to most homes, and households already have boilers. What if we could keep the infrastructure but change the gas?

That’s the promise of hydrogen. It shouldn’t be even remotely considered a direct swap, but it does offer the possibility of decarbonising the existing heating network rather than building a new one. That would obviously be less disruptive, and it would be based around technologies that are already familiar. Provided it was ‘green hydrogen‘ made with renewable energy, and that it could be scaled up to meet demand, we’d have a real large-scale solution on our hands.

One reason to be confident about the possibilities of hydrogen in our boilers is that we’ve done it before. The UK heats homes with natural gas today is because abundant supplies were discovered in the North Sea in the 1960s. As these were exploited, the existing gas grid was adapted to pipe it to homes as a new and cheap energy source. Britain’s original gas network was slightly different. It was based on ‘town gas’, which was made from coal and included a mix of gases, including clean-burning hydrogen – and not so healthy carbon monoxide.

Town gas was around 50% hydrogen, so while it sounds new to many of us today, it’s what my grandparents were burning when they first got hot water and central heating in their homes.

My boiler upstairs would readily burn a percentage of hydrogen in the gas mix, and adding a little more to the grid could be an intermediate step – perhaps up to 20%. Switching the grid to 100% hydrogen would be more technically changing. Most people would need new boilers, and the network needs to be updated from iron to plastic piping. Parts of the network can do this already, and work is due to be complete on the re-fit by 2031. Boilers that can burn hydrogen are on the market, although unfortunately new homes continue to be built and old boilers replaced with no view to the long-term future. That’s only making things more expensive later, and the government have no plans to prevent old-style boilers from being fitted until 2026.

Is this actually going to happen? Hard to say. There are a number of trials going on, and I’ve reported on a couple of them, like Keele University. The government’s strategy calls for a test neighbourhood, then a village. Next is a whole pilot town, which wouldn’t be until the end of the 2020s. As the results came in from that, we’d be looking at well into the 2030s before work really began on a transition.

In other words, it’s too early to tell if this is going to happen in Britain or not, and therefore how big a contribution it will ultimately make to our net zero plans. It’s a similar story in Germany, where the national hydrogen plan focuses on industry and transport, and is somewhat agnostic about heating and the grid. So too the Netherlands. “The potential is there,” says the plan, but “there are still important questions to be answered regarding applicability, safety, availability, sustainability and affordability. In the coming years, efforts will be made to provide answers to those questions.”

That seems to sum up the current state of play on hydrogen for domestic heating – potential, but lots of questions to answer. On transport however, things are moving quicker, and I’ll look at that next week.