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What is a Hydrogen Boiler? Here's What You Need to Know

Worcester Bosch's hydrogen boiler
(Image credit: Worcester Bosch)

Hydrogen boilers are an exciting new technology which could revolutionise the way we heat our homes, helping to lower energy costs and decrease our carbon emissions.

Currently around 85% of homes are heated with polluting natural gas, of which the main by-product is carbon dioxide. Heating our homes this way accounts for around 14% of the UK's carbon emissions, according to the Committee on Climate Change, and this is a significant obstacle for the government, which is striving to make the UK net zero by 2050.

In contrast, the main by-product of burning hydrogen gas is water. Hydrogen heating represents a way of greening up the gas grid, and hydrogen boilers can be a viable low-carbon heating system in the future. 

This is everything you need to know about hydrogen boilers, how they could benefit your home and when they will be made available. 

What is a Hydrogen Boiler?

A hydrogen boiler works in a very similar way to natural gas boilers. Whereas natural gas boilers burn gas (or methane), hydrogen boilers burn hydrogen. This creates hot flue gases that can be used to heat water. 

Is This The Same as a Hydrogen-Ready Boiler?

Not exactly. Some hydrogen boilers will be able to run on 100% hydrogen as well as natural gas, but other hydrogen-ready boilers such as Viessmann's Vitodens 100-W gas condensing boiler, run with a hydrogen mix of up to 20% and 80% natural gas.  

Last year, in the first HyDeploy pilot trial, 20% of hydrogen was injected and blended into Keele University's existing private gas network, which supplies 30 faculty buildings and 100 domestic properties. 

There is another hydrogen mix trial underway in Winlaton, a village near Newcastle, where 670 homes have become some of the first in the UK to trial natural gas blended with hydrogen. The trial will conclude later this year. 

Baxi's hydrogen boiler

Baxi Heating's 100% hydrogen boiler prototype. (Image credit: Baxi)

What are the Benefits of Owning a Hydrogen Boiler?

A major benefit of owning a hydrogen boiler is that it will reduce your carbon emissions, making your home environmentally friendly. 

Additionally, it could help to decrease your long-term energy bills. Hydrogen is more energy efficient than natural gas - there is equal energy in 1kg of hydrogen as there is in 2.8kg of gas, according to Power Technology - and this means you’ll use less fuel. 

Furthermore, when the UK’s gas network is able and ready to switch from methane to hydrogen, those with hydrogen-ready boilers won’t need to replace their heating systems. No changes will be required to pipework or radiators, and you won’t need to install a water tank. 

Plus, any hydrogen-ready boiler that is installed initially to run off natural gas should only require one hour’s labour to convert it to hydrogen.

How Much Will Hydrogen Boilers Cost?

In July, the boiler industry’s big four manufacturers confirmed that a hydrogen-ready boiler will cost no more than its natural gas equivalent. Baxi, Worcester Bosch, Vaillant and Ideal confirmed that a new price-promise will be introduced which could save homeowners £2.3 billion. 

Boiler Guide estimates that pricing would be similar to natural gas boilers - somewhere between £400 to £3,000 before factoring in the installation.

When Will Hydrogen Boilers be Available?

The boilers are not yet available to homeowners. But as the government confirmed in its August Hydrogen Strategy, ministers aim to consult later this year on the case for enabling, or requiring, new natural gas boilers to be easily convertible to use hydrogen by 2026.

Both Baxi Heating and Worcester Bosch have developed 100% hydrogen boilers which are undergoing testing in the UK, and both manufacturers have called on the government to fast-track their market release for 2025.

Hydrogen boiler trials ongoing

Both Baxi Heating and Worcester Bosch hydrogen boilers are being showcased in the UK’s first 100% Hydrogen Home public demonstration. (Image credit: Worcester Bosch)

Martyn Bridges, director of technical communication and product management at Worcester Bosch, told Homebuilding & Renovating that clarity from the government is important as to the next steps for release. 

“The sooner they say yes to placing hydrogen and hydrogen-ready boilers onto the market, the sooner we can get the investment needed to begin developing our portfolio.”

All eyes are now on the government’s Heat & Buildings Strategy, which will be published this month, to learn the cut-off date (expected to be 2035) for natural gas boiler installations in existing homes.

When this date is confirmed, it could mean that millions of British households will either need to replace their boilers with heat pumps or install hydrogen-ready boilers capable of running on hydrogen gas.

As part of the Future Homes Standard, gas boilers will be replaced by renewable heating systems in all new-build homes in 2025.

Are Hydrogen Boilers Safe?

"There is no carbon monoxide created from hydrogen, which is by far the biggest hazard with burning gas. We are very confident that hydrogen is safer than natural gas."

Martyn Bridges, Worcester Bosch

Earlier this month the government had to reiterate that hydrogen boilers will be safe after a study claimed hydrogen boilers could cause four times more explosions than natural gas boilers. 

Significantly, though, the study also revealed no carbon monoxide was created from the boilers - a major safety plus compared with natural gas boilers - and that the faulty boilers could have been fixed by installing two excess flow valves to easily regulate how hydrogen flows through the pipes.

Bridges said of the study: “The headline should have been that hydrogen boilers will save lives because there is no carbon monoxide created from hydrogen, which is by far the biggest hazard with burning gas. We are very confident that hydrogen is safer than natural gas.” 

And energy expert David Hilton, director of Heat and Energy Ltd and a contributor to Homebuilding & Renovating, remains upbeat over the future use, and safety, of hydrogen boilers. 

“Yes, we’re dealing with hydrogen, but the information is there to ensure boilers are safe. We need to look at how safe our infrastructure is, which can be done through annual inspections, and this will be especially important when the government changes the mix of hydrogen blend within the gas network.

“Another way to mitigate the risks is to have a transition period. For example, hydrogen is not compatible with steel pipes, so there’s a lot of transitions that need to happen: it may be that every house which uses a hydrogen boiler needs to be checked first.”

Are They a Viable Alternative to Heat Pumps?

While renewable tech such as air source heat pumps and ground source heat pumps, which run off electricity, will be vital in heating our homes, this technology will not be suitable for all homes. 

This is where hydrogen boilers can step in. But experts believe that the future of renewable heating will comprise both solutions.

Rick Bruins, business development manager at Remeha, part of BDR Thermea Group in the Netherlands. told Homebuilding & Renovating that a small heat pump would be effective for tackling outside temperatures up to 0ºC, then when it starts to freeze, the hydrogen boiler would begin to heat up the home. 

“Installing a heat pump with enough power to heat a home which is -10ºC is very expensive, but hydrogen is expensive too, so the combination of the two would make for a cost-effective solution,” said Bruins.

Jack is News Editor for Homebuilding & Renovating, and strives to break the most relevant and beneficial stories for self builders, extenders and renovators, including the latest news on the construction materials shortage and planning reforms. Having bought his first home in 2013, he and his wife have renovated almost every room and recently finished a garden renovation.