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What are hydrogen boilers?

Even prior to COP26 in November, the news has been full of talk about how the UK will meet its ambitious climate change target of achieving net zero by 2050. From electric cars; to jet-zero; to carbon-trading; to heat-pumps; and to hydrogen boilers - it’s not easy to keep up with what’s going on! So, you might be wondering about what all of these changes mean for you and your home. Misleading newspaper headlines have had people worrying that they’ll soon need to fork out for a hydrogen boiler or a heat-pump because their gas boiler has been ‘banned’ and is soon to be evicted from their home! But this isn’t true. In this blog, we’ll bring you up to speed with what a hydrogen boiler is; why there’s talk of introducing them; and what this means for the future of heating our homes.

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Worcester Bosch hydrogen ready boilerWhat are hydrogen boilers? Even prior to COP26 last month, the news has been full of talk about how the UK will meet its ambitious climate change target of achieving net zero by 2050.

From electric cars; jet-zero; carbon-trading; heat-pumps; and hydrogen boilers – it’s not easy to keep up with what’s going on!

So, you might be wondering about what all of these changes mean for you and your home.

Misleading newspaper headlines have been worrying people that they’ll soon need to fork out for a hydrogen boiler or a heat-pump because their gas boiler has been ‘banned’ and is soon to be evicted from their home!

But this isn’t true.

In this blog, we’ll bring you up to speed with what a hydrogen boiler is; why there’s talk of introducing them; and what this means for the future of heating our homes.

Will gas boilers be banned?

In a word, no.

There have been lots of attention-grabbing headlines about gas boilers being ‘banned’ from 2025. But this so-called ‘ban’ actually refers to the government’s plans to prevent all new-build homes from installing gas and oil boilers from 2025. It doesn’t include current housing stock.

Read our related blog: ‘The truth about the ‘The Boiler Ban’, to find out more about this.

According to the government’s recent ‘Heat in Buildings’ strategy, the ambition is that new gas boilers won’t be installed from 2035.

So, unless you buy a new-build house after 2025, the ban will not impact you. Any boiler you buy today will probably use natural gas for all its working lifetime i.e. the next 10 to 15 years. 

From 2035, you won’t be able to get a traditional gas boiler replacement when your old one breaks. 

After gas boilers have eventually been phased out, there will be two main ways of heating your home: either with a heat pump or a boiler that runs on hydrogen gas.

We’ve written a related blog on what heat-pumps are, but today we’re putting hydrogen boilers under the spotlight.

Why do we need to switch to heat-pumps and hydrogen boilers?

A hydrogen ready boiler and heat pump.Under the Paris Agreement, the UK has a legal commitment to reach net zero carbon emissions by 2050. By achieving this, we can hopefully limit global warming to 1.5C, and thereby avoid  catastrophic effects of climate change.

Since burning fossil fuels to heat our homes produces a third of our carbon emissions, we ultimately have to move away from using them.

Even though our current boilers are much more efficient than they used to be, heat-pumps and hydrogen boilers are much more environmentally friendly.

But replacing gas boilers is a tricky task because we will need to change lots of infrastructure.

What are our options?

So, we’re likely to see a mix of low-carbon technologies such as air-to-water or ground-to-water heat pumps, heat networks, and potentially switching the natural gas in the grid to low-carbon hydrogen to run hydrogen boilers.

Whilst the government has been clear that it wants to be installing 600,000 heat pumps per year by 2028, the future of hydrogen heating is less clear. 

As set out in the Prime Minister’s Ten Point Plan for a Green Industrial Revolution, the government is aiming for 5GW of low carbon hydrogen production capacity by 2030 for use across the economy. This will be no mean feat since there’s virtually no low carbon hydrogen produced or used currently.

The government has announced that they will ‘explore the potential’ to use hydrogen for heating buildings (using a Hydrogen Village trial) and will make a decision on it in 2026.

So, whilst we’ll look at what hydrogen boilers are; and how they work; it’s important to recognise that as of today, their future is uncertain.

Any changes that do happen will be a step-by-step transition that will happen over many years.

But boiler manufacturers are ready for this. Many are showcasing ‘hydrogen-ready’ prototypes.

What is hydrogen?

The symbol for hydrogen.You might be wondering how hydrogen – which is a gas – is ‘greener’ than our current natural gas

Well, the premise of using hydrogen to fuel our boilers is that it will reduce carbon emissions.

Our traditional boilers burn natural gas, LPG, or oil to create heat.

Unfortunately, when they burn these fuels, they release carbon dioxide into the atmosphere. Carbon dioxide is one of the greenhouse gases which is responsible for global warming and climate change. 

Hydrogen is different because it’s a clean-burning molecule. When water and hydrogen react to make electricity, they don’t release carbon – the only by-product is water. 

Why haven’t we been using hydrogen before now?

As we’ve mentioned Hydrogen is much ‘greener’ than our natural gas, and it’s also more abundant. It’s about 1,800 times more plentiful than oxygen! So, why haven’t we been using it before now?

Well, unfortunately, Hydrogen needs to be separated from other elements before it can be used.

The two main ways of doing this are by electrolysis or Steam Methane Reforming (SMR). The ‘cleanest’ way is by electrolysis using a renewable energy source.

But at present, 99% of Hydrogen is still made using fossil fuels, usually through a pollution-heavy process.

So, to meet our climate goals, we’ll need to make so-called ‘green Hydrogen’ using electricity from renewable resources, such as wind and solar power.

As you can probably imagine, this is a more expensive and complicated process than just burning the coal we dug out of the ground in days gone by!

How would hydrogen boilers be phased in?

As we’ve mentioned, the government isn’t planning to make any firm decisions on hydrogen heating until 2026, when timescales and technical details will hopefully be ironed out.

But, introducing hydrogen boilers would be likely to happen in three stages:

Stage 1 – Production of hydrogen boilers

The first stage in a transition to hydrogen would involve manufacturing new boilers to be able to run on 100% hydrogen. Currently, there are no 100% hydrogen boilers available, but a few of the bigger boiler manufacturers have created prototypes.

Stage 2 – Introducing a hydrogen-blend of gas

The next stage would be introducing a blend of natural gas and 20% hydrogen into the UK mains supply.

Some manufacturers are describing their newer boilers as being: ‘hydrogen-blend ready’. But this is misleading because virtually all boilers that are already installed in UK homes are!

Nearly all boilers are already able to run on a blend of hydrogen and natural gas. This means that this stage could come in almost instantly, and you probably wouldn’t notice any difference!

The HyDeploy programme at Keele University is testing the effects of using this hydrogen blend. It’s thought that using a blend alone would save approximately 7% in CO2 emissions, so it’s already a step in the right direction.

Stage 3 – Switching to 100% hydrogen

The final stage would be to switch the gas supply from the gas and hydrogen blend to 100% hydrogen. At this stage every new boiler sold in the UK would need to be a hydrogen boiler, and would look very similar to a traditional gas boiler.

What is a hydrogen boiler?

Hydrogen Boilers are very similar to our traditional gas boilers and could provide a like-for-like replacement should we switch the gas network to hydrogen gas.

Hydrogen boilers look virtually identical to gas boilers. Installing them will be a very similar process, as they too would be connected to the mains.

The big difference is, that as well as being able to run on natural gas (which is mostly methane) hydrogen boilers can run on 100% hydrogen.

This is much better for the planet because hydrogen is a carbon-free energy carrier and burning hydrogen for fuel produces no carbon dioxide at the point of use.

How does a hydrogen boiler work?

Hydrogen boilers are similar to traditional gas boilers that we’re familiar with. They’re built and function in much the same way.

Viessmann has a really good article and video on this, which we’ve linked to at the end of this blog. But we’ll summarise here.

Firstly, a hydrogen boiler would take in oxygen and hydrogen. The hydrogen will come from the main gas supply and the oxygen will come from the air.

A catalytic burner ignites a mix of hydrogen and oxygen. This burning of the gases creates hot flue gases which enter the boiler’s heat exchanger. The heat exchanger is surrounded by cold water, which is heated by the hot gas.

The hot water can heat your home and supply hot water to your taps.

This process looks very similar to what happens with a traditional boiler, but the only by-product from burning hydrogen and oxygen is water (rather than carbon dioxide). The condensate pipe takes this water away.

The hot flue gases (hydrogen and oxygen) can also exit the system via the flue along with some NOx emissions as a result of hydrogen combustion.

When will hydrogen boilers be available?

A woman thinkingCurrently, there are no 100% hydrogen boilers available. However, Viessmann, Baxi and Worcester Bosch have produced prototype “hydrogen-ready” boilers capable of burning either natural gas or 100% hydrogen.

Worcester Bosch say their engineers can convert their boiler from natural gas to hydrogen gas in about an hour.

How much would a hydrogen boiler cost?

The simple answer is, we don’t know!

There’s far too much uncertainty around the future of Hydrogen boilers to say. But there’s speculation that they won’t cost much more to buy than a traditional gas boiler.

The real issue is likely to be the running cost, because that could be around 2-4 times more than natural gas. This is why many favour the idea of heat-pumps as the best way to decarbonise our home heating.

What are the advantages of hydrogen boilers?

Let’s take a look at what we stand to gain from switching our traditional boilers to hydrogen ones…

A woman pointing to the symbol for carbon.Emissions from hydrogen boilers contain zero carbon

First and foremost when we’re talking about tackling climate change, is that hydrogen boilers produce no carbon. When you burn hydrogen fuel, all you get is heat and water. This is much more environmentally friendly than burning natural gas, which releases lots of carbon dioxide into the atmosphere.

 

Hydrogen is a renewable energy source

So this is another advantage over burning fossil fuels, which are rapidly running out.

Hydrogen is more efficient than gas

Hydrogen is much more efficient than natural gas. One kg of hydrogen can produce almost the same amount of energy as three kgs of fossil fuels. This means that you’ll need to burn less fuel to heat your home. At the moment that isn’t like to save you money on your energy bills though, because of the current high cost of producing hydrogen. 

Hydrogen boilers can use our existing gas infrastructure

Lots of different boilers.A big advantage of using hydrogen for our heating is that it wouldn’t require any behaviour change from us. A hydrogen boiler would look the same and provide the same delivery of comfort as our traditional boilers.

Some people worry about using a heat-pump (although we think these fears are unfounded!) and this solution would avoid the costs and learning curve of households adopting a completely new heating system.

It could be rolled out quickly across the UK because our existing gas infrastructure would be used to deliver the new hydrogen fuel.

Hydrogen boilers may be better than heat-pumps for homes with high levels of heat loss

A calculator next to a thermal image.There has been much discussion in the media about the need for a ‘Fabric First’ approach before low-temperature heating systems such as heat-pumps can work effectively.

Fabric First refers to the need to have decent insulation in order to reduce heat loss and maximise the efficiency of our heating systems.

Unfortunately, the UK has some of the worst insulated homes in Europe. Whilst we do need to tackle this regardless – this would be less of an immediate problem for a hydrogen boiler.

Compared to other technologies, boilers are a good option in hard-to-heat buildings because of their resilient heat delivery. They’ll be able to deliver consistent performance even in homes with high rates of heat loss.

Hydrogen also offers benefits for the energy system as a whole.

Another bonus of creating a national hydrogen infrastructure is that there could also be  wide-scale use of hydrogen for commercial and heavy transport.

What are the disadvantages of hydrogen boilers?

Unfortunately, there are some concerns about the feasibility of hydrogen heating, but this is under careful scrutiny by the government before any decisions are made…

Hydrogen is not cheap to produce

As we’ve mentioned, hydrogen doesn’t exist in a pure form, it has to be separated from other elements first. To do this in an environmentally friendly way isn’t cheap.

Right now, producing hydrogen is too expensive to be viable to provide nationwide supply. Researchers are investigating more affordable ways to produce hydrogen.

Some methods of producing hydrogen use fossil fuels

As we mentioned earlier, one of the most widely used methods of separating hydrogen for use as a fuel is by Steam Methane Reforming (SMR). This process generates quantities of the greenhouse gases that we wish to avoid. 

The technology isn’t proven yet

While some prototype hydrogen boilers exist, they need to be proven at scale before they can be rolled out. This is why the government has created so-called ‘hydrogen villages’ to test the technology.

Need for enabling infrastructure

Although we can use the existing gas infrastructure to deliver hydrogen, some adaptations will still need to be made.  For example, electronics must be explosion-proof, given the flammability of hydrogen – we’ll get to that! 

Hydrogen is flammable

Hydrogen has the National Fire Protection Association’s highest rating of 4 on the flammability scale. It’s flammable when mixed even in small amounts with ordinary air; and it has a lower ignition energy than gasoline or natural gas. This means it can ignite more easily.

Hydrogen is difficult to store

Due to the differences in flammability and composition, the storage of hydrogen gases is more complicated than with natural gas.

Final thoughts…

What’s clear is that to meet Net Zero virtually all heat in buildings will need to be decarbonised. The government has set the ambition of phasing out the installation of new natural gas boilers from 2035.

Precisely what the future of heating entails, is not yet determined. But it’s likely that it won’t be a one-size-fits-all approach. We’re likely to see a mix of low-carbon technologies being used for heating – perhaps including hydrogen boilers – but we’ll have to wait for the government’s announcement in 2028 to know for sure!

In the meantime, for tailored advice on the best heating sol

Useful links:

Worcester Bosch video on Hydrogen boilers

Viessmann article: How hydrogen boilers work

The government’s 10 Point Plan for a Green Industrial Revolution

The UK’s Hydrogen Strategy