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Sunday sit-down with…Dr Sara Walker

After the government published their Hydrogen Strategy last month – which outlined that hydrogen could be used to heat as many as 3 million homes by 2030 – we caught up with the Director of The Centre for Energy to understand what this could mean for us in the battle against global warming

Written by Becky Hardy
Published 11.09.2021

It’s not as though we really needed our memories jogged, but if the extreme flooding in London and recent wildfires in Greece and Turkey have served as a reminder of anything, it’s that we all need to be doing everything we can to tackle the global warming crisis. Now.

Luckily, the urgency of this message is starting to get through to our government. Last month, the Department for Business, Energy & Industrial Strategy published the UK Hydrogen Strategy, which sets out their approach to developing a thriving, low-carbon hydrogen sector in the UK to reduce our carbon emissions and help battle climate change. 

One point above all others in this strategy stood out to us – that, by 2030, hydrogen could be used to heat as many as 3 million homes. 

Would we decide whether we made that switch? Is it safe? Would we notice the difference? What would a change to hydrogen heating mean for us as individuals? And could a straight swap really be as energy-efficient as the government would have us believe? 

Well, we’re no experts. Luckily in our line of work, though, we know a few. That’s why we got in touch with Dr. Sara Walker, Director of The Centre for Energy, to find out a little more…. 

The UK Hydrogen Strategy has suggested that hydrogen could be used to heat as many as 3 million British homes by 2030. Is this likely to actually happen? 

The strategy has set out plans for testing the use of hydrogen in up to 67,000 homes by 2030. They think the amount of hydrogen they can produce by 2030 is the equivalent of what 3 million homes might use, but the plan is for that amount to mainly be used in industry and in some transport applications. 

What kind of industries would use hydrogen? 

You can use hydrogen as a chemical feedstock, so there’s already demand within some chemical industries for hydrogen. We’re also looking at whether hydrogen can be used in steelmaking to decarbonise the production of steel, so that industry could potentially be a big user of hydrogen too. 

But any industry where there’s a big demand for heat, really – instead of using natural gas for high-temperature gas furnaces, we could potentially use hydrogen. 

How does hydrogen work as a source of heat?

Any combustion process needs a fuel, a source of ignition and oxygen for the “burn” to happen. The chemical composition of natural gas is CH4, so there’s already hydrogen in there, alongside carbon. When you use natural gas in a boiler you’re combusting it, and a natural by-product of that process is carbon dioxide. But if you are using purely hydrogen, then the by-product of the combustion process is water. That’s why it’s seen to be a relatively clean fuel, because it doesn’t have any carbon associated with it.

Where is pure hydrogen sourced from? 

Very little hydrogen occurs on its own naturally. It tends to be within other molecules that we then need to break down. At the moment, around 95% of hydrogen is created by breaking up natural gas. You separate the carbon and the hydrogen in natural gas using a chemical process and store the carbon using carbon capture, keeping carbon emissions relatively low. This is what they call “low-carbon hydrogen” in the Hydrogen Strategy.

The other thing you can do is take water – which we know has hydrogen and oxygen in – and pass electricity through it. This creates a process called “electrolysis”, which breaks the hydrogen and oxygen up into their separate elements. If you use renewable energy to generate the electricity and use the electricity to split the water into its two elements, that’s what’s called “green hydrogen” – because you’re not producing any carbon in that process at all. That’s the cleanest way that we can create hydrogen, but it’s not a very efficient process.

Is it likely, then, that most of the hydrogen we generate by 2030 will come from breaking down natural gas? 

Yes. The government has a target of creating 15 Gigawatts of hydrogen by 2030, and it thinks that the green electricity systems that are planned – and which could be operating by then – will account for around 5 Gigawatts. So it’s not going to be more than a third of the hydrogen we produce that will come from green sources. It’s much more likely that we’ll mostly be using what we call “blue hydrogen”, where we break down natural gas and capture the carbon. 

There are pros and cons of using mostly blue hydrogen. One advantage is that we are, at least, creating some hydrogen and hopefully giving people (mainly in industry) the confidence to switch to using hydrogen instead of natural gas to help create that demand. But the danger is that, if you commit to using mostly low-carbon and invest in all that technology, you’ve got less money to then invest in the green processes. So you’re making that investment choice early on, which may bring future limitations with it. The issue is, at the moment, there isn’t enough green hydrogen in development, whereas using low-carbon hydrogen is a way to kickstart the demand.

What would a switch to hydrogen heating in our homes mean for us, as individuals?

If you were to go 100% hydrogen in your home, you would still have a gas boiler – it would just be using a different type of gas. Hydrogen has a slightly lower energy content per unit volume, so one metre-cubed of hydrogen has slightly less energy in it than one metre-cubed of natural gas. This means you’d use a little bit more gas by volume overall. You wouldn’t really notice that so much and it would only matter if both gases cost the same, as you’d need to be using more hydrogen so would spend more. But we don’t know what the prices of hydrogen are going to be like yet, we’re waiting to see on that one.

If your cooker is natural gas currently and you switch to hydrogen, you might notice less of a flame when the hob is lit. Hydrogen is relatively colourless and doesn’t smell, but for health and safety reasons the research teams are thinking about adding a colour and an odour to it, so that you can see more clearly when the flame is lit or can smell if you have a leak.

And would we need to prepare our homes in any way before we could make the switch to hydrogen heating?

One thing that would need replacing in your home is your gas pipework. You’d normally have a system of copper pipes for natural gas, but hydrogen is a really small molecule and it can actually escape through that kind of pipework. So you would need to replace your copper pipes for plastic ones.

Is using hydrogen to heat our homes safe?

It’s pretty much the same risk as natural gas. Natural gas can cause explosions – so can hydrogen. The only difference with hydrogen is, because it’s such a small molecule, it’s also quite light – so if you were to have a leak, it would disperse quicker than if you had a natural gas leak.

Obviously, there have been some concerns with our knowledge of the Hindenburg disaster, so research has proceeded very cautiously. But it’s important to remember that the passenger airship LZ 129 Hindenburg had hydrogen that was contained in a particular volume and so couldn’t disperse. Whereas if you had a hydrogen leak in your home, the hydrogen molecules are small enough to be able to disperse and not cause too much of an explosive hazard.

Is the Centre for Energy currently working with hydrogen directly?

Yes, my colleagues are. I’m looking at the bigger picture – so I’m thinking about hydrogen alongside a whole load of other potential solutions to see what works well for certain uses.

But some of my colleagues are looking directly at how to make producing hydrogen cleaner and more cost-effective, using different chemical processes. They’re involved in a big research project called H2FC Supergen: The Hydrogen and Fuel Cell Research Hub.

How effective could switching to hydrogen over natural gas in our homes and in industry be in the global battle against global warming?

In my opinion, it’s important that we think about all possible solutions and don’t write anything off too early, because the challenge that we’ve got is massive! I think hydrogen will be really effective in industry where electrification isn’t really going to achieve what’s needed. And also for long-distance travel, where batteries just can’t provide the range for ferries, ships and aviation. Potentially for rail travel too, although you can electrify your railways. So those are the most appropriate uses for hydrogen.

I think in terms of the battle to reduce carbon in our homes, for most of us, the best option is going to be the electrification of our heating: using cleaner, renewable electricity to heat our homes. That alongside lots of insulation – because the best thing we can do is not need to use as much heating. In the same way that, every few years, we like to buy a new kitchen, we should be upgrading our home’s insulation regularly. It’s not necessarily the same visual impact as a new kitchen, but it can save us money and help save the planet in the long term.


To find out more about The Centre for Energy and the work Sara and her team are doing towards fighting global warming, visit their website.

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