Hydrogen boilers: are they the solution to net zero home heating?

23 June 2021 | Celia Topping

The global fight against the climate crisis is well and truly underway. But one of the biggest challenges to lowering our nation’s carbon footprint comes from heating our homes. 

About 17% of the UK’s total carbon emissions are created from home heating. Add to that another 6% for cooking and hot water, and that’s almost a quarter of all carbon emissions coming from the domestic market1. And because 8 out of 10 homes still use gas boilers, a staggering 23 million homes are still burning fossil fuels

Why do we need an alternative to gas central heating?

Finding an alternative technology to decarbonise our home heating systems is key to helping us reduce the nation’s carbon footprint – as well as meeting the UK’s zero carbon by 2050 target. The UK government has introduced energy efficiency measures for boilers, and announced that no more gas or oil boilers will be installed after 2025 in new-build homes2. But the challenge of finding a long-term home-heating solution for existing homes remains.

At OVO, we’re already offering solutions. We’re installing some practical low-carbon heating options – like electric heat pumps – that use 100% renewable electricity instead of fossil fuels. And the green energy we’re supplying to electrify heating systems is also a powerful tool in the fight against the climate crisis.

But, there’s a buzz around another potential solution to decarbonising heat: using carbon-free hydrogen gas to burn in boilers, instead of the natural gas we currently use. But could hydrogen really be a solution for net zero home heating? 

What is hydrogen?

Hydrogen is the most abundant natural element in the universe. It’s about 1,800 times more plentiful than oxygen4– and it’s estimated that 90% of the visible universe is made up of it. Hydrogen is also carbon-free, unlike natural gas, so burning it as a fuel releases none of the carbon emissions that contribute to global warming.

So far, so good. So why haven’t we been using hydrogen gas as a fuel up to this point? Unfortunately, unlike natural gas, crude oil and coal, hydrogen doesn’t occur naturally in a pure form. It has to be separated from other elements – and the main method of doing this involves burning fossil fuels. And while it’s possible to do this safely, it’s an expensive, energy-intensive and complicated process. More about that in a moment. 

What is a hydrogen boiler? 

To you and me, a hydrogen boiler would look pretty much the same as a regular gas boiler – and it would work in a similar way, too. The only difference is that it would burn carbon-free hydrogen instead of natural gas, a fossil fuel

This means if every home in the UK had one, we could reduce our carbon emissions by up to 20-25%5. This sounds great – but the fact remains that hydrogen boilers are not yet available to buy. More about that in a moment. 

How do hydrogen boilers work? 

Hydrogen boilers could work in a similar way to modern condensing boilers with many of the same internal working parts. And they could be installed and connected to the network in much the same way. There are only a few components which would need to change, such as the flame detector and burner.

Advantages of hydrogen boilers 

The major environmental benefit of hydrogen is that it produces no carbon dioxide or carbon monoxide when burned. Let’s look at the other advantages of using hydrogen gas to heat our homes:

  • Familiar heating system – because hydrogen boilers would look and work in much the same way as our old boilers, they could offer the same comfort and control to the end user – with little behavioural change needed
  • Easy to install – once a home is made hydrogen-ready, the process of installing a hydrogen boiler would be much the same as a natural gas boiler. No extra space or equipment should be needed, either inside or outside the home.

Disadvantages of hydrogen boilers

This all sounds great, so what’s the catch? Well, the problem is, there’s no 100% hydrogen available in the grid to heat homes now, or in the near-future. And most importantly, hydrogen boilers are still in the prototype stages. Even if they were available, hydrogen heating is a very new technology. Let’s have a look at the challenges:

Availability and timing

Hydrogen isn’t currently available in the gas network for households to use. And research tells us that it won’t be ready at a scale that could serve homes across the country until at least after 2030. In the meantime, we need to take action against the climate crisis now – by installing available technologies in homes, to reduce carbon emissions before we run out of time. 

Hydrogen isn’t an immediate solution for home heating – and waiting for it to arrive means delaying much-needed action. Particularly if the hydrogen never arrives, or is hugely expensive when it does!

The challenges of producing carbon-free hydrogen

Producing hydrogen in a carbon-free way is not the simplest of processes. The dominant form of hydrogen production available today is Steam Methane Reforming (SMR). SMR works by reacting steam with methane (natural gas), which results in a form of hydrogen called  “grey hydrogen”. 

But this process produces carbon as a by-product – so using this hydrogen in our homes wouldn’t help reduce emissions. In fact, it’s worse than just using natural gas, because the process is not very efficient. 

Fortunately, the carbon can (in theory) be captured and stored before it’s released into the atmosphere. But it’s an expensive process, and is unproven at scale. Plus, SMR comes with its own challenges, as the process has the potential to leak methane into the atmosphere, further contributing to climate change

Electrolysis is the more eco-friendly method. Here, renewable electricity can be used to split water molecules into 2 separate hydrogen molecules. This is known as green hydrogen – but it’s unavailable at scale, and because it takes a lot of electricity to split water, it’s expensive. This same electricity could be used with technologies like heat pumps, instead.

Safety issues

Hydrogen has not yet been proven to be safe for use in homes at scale. Problems include nitrous oxide emissions from burning, and a risk of explosion from “light-back”, leakage, and the colourless flame hydrogen produces. These all create significant safety concerns, which have not yet been fully addressed – even though progress is being made in trials underway at the moment. 

Infrastructure issues

Although we already have a pipeline network, is the system ready for the lighter, smaller molecules of hydrogen? National Grid is still figuring out whether the existing network would be suitable. If not, it’s not clear how much it would cost to upgrade. 

Converting existing appliances 

Every single consumer appliance that’s currently connected to the gas grid would need to be replaced with hydrogen-ready appliances. This includes not only boilers, but also hobs, gas fires and in-home pipeworks. Plus, heating engineers would all have to be retrained, and qualified to be able to fit the new appliances safely. At the point of switch over, entire streets would need to be done together – meaning every house would need to have appliances swapped or upgraded at the same time.

Hydrogen will be needed elsewhere

Getting away from fossil fuels will be easier in some sectors, and more difficult in others. For "hard to decarbonise" sectors that can't easily be electrified – like energy-intensive heavy industry, heavy-duty transport, aviation and shipping – green hydrogen offers a potential solution to replace the oil and natural gas that they currently rely on. 

If we want to reduce carbon emissions across the whole economy, there are already other solutions available to homes. It'd be wise to focus resources on powering the  sectors mentioned above with green hydrogen – we can opt for other low-carbon solutions like electrification in sectors like home heating. 

It’s 50% inefficient

The energy content of hydrogen compared to natural gas is about a third lower. Which means a 20% hydrogen blend in the gas grid would only give 4 to 6% carbon savings6. Plus, hydrogen has to go through a lot of processes  to heat the water in your radiator. Each step wastes some energy, which adds up to around 50% of the energy used to deliver hydrogen heating being wasted.

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Are hydrogen boilers available to buy?

It’s going to be a long  time before you see hydrogen boilers for sale – which makes sense, because there’s no hydrogen gas grid available yet! 

But some companies – like Viessmann, Baxi and Worcester Bosch – have produced prototype “hydrogen-ready” boilers capable of burning either natural gas or 100% hydrogen. Worcester Bosch claim their boiler could be switched from natural gas to hydrogen gas in about an hour by one of their heating engineers. 

But with no hydrogen around to burn for at least 10 years or so, you’d be better off doing your bit for net zero by going electric

When will hydrogen boilers be available?

Not an easy one to answer! But current forecasting predicts hydrogen won’t be commercially available until 2030 at the very earliest. And even then, it may not be for domestic use.

The government’s currently working with the heating industry on hydrogen research and development, with trials taking place across the country. Projects include H21. which is sponsored by Ofgem, Hy4Heat which is trying to establish whether it’s technically possible, safe and convenient to replace natural gas with hydrogen, and HyDeploy with Keele University acting as a test centre. In total, the UK government has invested £20million in Hydrogen Supply Programmes so far.

In the government’s recent Heating and Building Strategy report10, hydrogen was only referred to as a potential way of heating buildings. A final decision with regards to its use will be deferred until 2026. Roger Harrabin, the BBC’s  Energy and Environment Analyst, commented on the Net Zero Strategy, which was released the same day, “it looks unlikely that there will be much hydrogen left over [after industrial uses] to heat people’s homes11”.

How much would a hydrogen boiler cost?

With the reality of a hydrogen system so far away, it’s not easy to estimate the cost of a hydrogen boiler. There’s so much uncertainty surrounding the prospect, it’s really too early to put a price on it. But, it’s thought that a hydrogen boiler shouldn’t cost much more than a regular gas boiler. 

The more difficult part is the running cost. By the best estimates, hydrogen could cost 2 to 4 times more than natural gas. This cost is one of the main reasons why electrically-driven heat pumps are viewed as the best alternative to fossil fuel heating – especially when compared to hydrogen boilers.

How to make your home heating more efficient: the action you can take now 

We’re in the middle of a climate crisis, and we need to take action now. Hydrogen is a distant solution, if a solution at all – so let’s look at the alternatives already powering a low-carbon, long-term solution for home heating. 

Switch to a low-carbon heating system

Considering the challenges posed by hydrogen, it’s hard to see an easy future with this “new” gas. The electrification of heat, on the other hand, gives a practical solution now. Heat pumps have been around for at least a decade – and they give us a long-lasting, workable alternative to natural gas. 

The  best leading low-carbon, low-maintenance technologies available today are:

  • Air source heat pumps. This electrical heating system can run purely on renewable energy and so it’s a truly low-carbon option for heating your home. They work by taking energy from the air outside and converting it into heat for your home – like a fridge, but in reverse! 
  • Ground source heat pumps.  This system absorbs heat from the ground, using pipes buried in your garden – before transporting this heat into your home. These heat pumps also run on green energy, so they’re low-carbon. 

Electrifying our heating system is a big step towards our 2050 net zero goal – and with the governmental subsidies and grants available, they’re the smart choice for a green future. 

Get a condensing boiler

If you’re not ready to go electric just yet, you can still make your home more efficient, and cut your carbon footprint, by updating your boiler. Your boiler is the beating heart of your home’s hot water and heating system, so making sure yours is energy-efficient is a vital step.

Replacing an old boiler with a modern condensing boiler is an efficient, effective way to reduce your bills, and cut your carbon emissions. You can also double-up on your home’s carbon-kicking kit by installing a tadoº smart thermostat. This clever little device syncs with your boiler – making it simple to control your heating and hot water from wherever you are, and reduce your energy bills by up to 31%7. OVO members get a whopping big discount too! 

While replacing an old boiler is a great step, there are also some other clever ways to make your home more energy-efficient. Read on to find out more. 

5 more ways to make your home more efficient 

mother with son at home reading

Hydrogen could be a solution. But it’s not one we’ll be using today, tomorrow, or even next year. In the meantime, the best way to cut your carbon footprint is to focus on being energy-efficient around the home. We’ve created a bunch of articles explaining how you can cut your energy use, and make your home more efficient. Here’s a quick summary of 5 key wins:

  1. Insulate – it doesn’t need to be expensive, but insulating your roof and walls can make a huge difference to your home’s warmth, and your bills
  2. Draught-proof – leaky windows and doors are a main cause of energy loss in UK homes, and could cost you up to £160 a year – so learn how to draught-proof them
  3. Change your lightbulbsswitching old incandescents for LEDs can save you big bucks
  4. Get a smart meter – we offer an award-winning smart meter installation experience, so you can keep a closer eye on your energy use, cut your costs and get more accurate bills 
  5. Switch to a better energy plan – the quickest way to cut your bills is by shopping around for a better plan – preferably with a green energy company like OVO!
  6. Choose energy-efficient appliances – from fridges and freezers to dishwashers and washing machines, you can save hundreds of pounds a year with a better-rated model

It’s not just big-spend home-improvements that can save you money. Small tweaks in your daily habits can be just as rewarding. Check out our 120 energy saving ideas, for ways to make a difference every day.

Join OVO on our mission to decarbonise home heating

Interested in being a heat pump pioneer? You’re in the right place! 

Share your contact details via the link below, and we’ll make sure you’re the first to know about OVO’s green tech offers and trials. 

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Sources and references:



3 and 8. 100% of the renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on Renewable Energy Guarantee of Origin certificates and how these work. A proportion of the electricity we sell is also purchased directly from renewable generators in the UK.




7. An independent study has shown that installing and correctly using a tadoº smart thermostat can reduce your energy use from heating by up to 31%. The study found that the tadoº device can reduce heating energy requirements by 14-26% through controlling the heat source (e.g. boiler or heat pump). You could also save another 7% by turning down the heating based on the weather forecast, depending on the window sizes. If the window surfaces are relatively large, the energy saving will increase.

9.  Each year, OVO plants 1 tree for every member in partnership with the Woodland Trust. Trees absorb carbon dioxide from the atmosphere, so tree-planting helps to slow down climate change.



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