Hydrogen gas as a low carbon fuel source, able to benefit from utilising the existing gas network infrastructure, is currently a hot topic that will continue to be so for the coming decade.

We take a look at what Hydrogen is, how it’s produced, and when it may be used to heat our homes and buildings in the future.

Currently there is no policy in place to confirm if and when hydrogen will replace natural gas (methane) in the gas grid, or once agreed how it will become widespread in its use.  Given its low carbon footprint, and many of
the retrofit challenges other technologies have in our hard to heat homes and buildings, hydrogen is seen as a key technology to facilitate the UK’s pathway to net zero by 2050.

Hydrogen enables us to transition from fossil fuel high carbon gas to a low carbon alternative. But many questions on the production, storage, and roll out are as yet unanswered. 

The Government’s long awaited UK Hydrogen Strategy was released in August 2021 and is very much a top-level strategy addressing infrastructure and development of a hydrogen economy in the UK. It discusses the potential for hydrogen to play a role in decarbonising several different sectors including transport, industry, buildings. Whilst the document acknowledges that hydrogen may play a role in the future it doesn’t commit to it. It states that  more evidence is needed on the costs, benefits, safety, feasibility, air quality impacts, and consumer experience of using low carbon hydrogen for heating relative to other more established heat decarbonisation technologies.

Why is hydrogen being considered?

The main reason hydrogen is being considered is its green credentials. When burned, hydrogen produces no CO₂ emissions, creating just water vapour and heat. Hydrogen contains a large amount of energy making it efficient. Today most domestic UK heating systems run off natural gas (methane), present in over 85% of all homes. The existing infrastructure can be utilised and upgraded where required to distribute hydrogen effectively. Hydrogen being also easy to store is another benefit; it can be compressed, held in salt caverns or liquified as required.

Despite hydrogen’s green credentials consideration must be given to the method of production which for some derives how ‘green’ it is.

What are the different methods of producing hydrogen?

Grey hydrogen

is hydrogen produced using fossil fuel such as natural gas (methane). When natural gas is separated into hydrogen and CO₂ by Steam Methane Reforming (SMR), with the excess carbon generating CO₂. Grey hydrogen is the term used whenever the excess CO₂ is not captured but gets emitted to the atmosphere, and is how most hydrogen is currently produced.

Blue hydrogen

follows a similar process to grey hydrogen but the CO₂ emissions are captured and stored, often in underground caverns, through carbon capture and storage (CCS). This mitigates the environmental impact on climate change through the elimination of greenhouse gas emissions. There is significant work and investment being made on carbon capture, utilisation, and storage (CCUS) to develop this blue hydrogen technology.

Green hydrogen

is the ultimate low carbon fuel – and is produced from electrolysis powered by renewable electricity (wind, solar, or hydro). The process splits water and separates off the hydrogen, with no direct impact on the environment. With the decreasing cost of renewable electricity and its non-reliance of fossil fuels, experts agree green hydrogen is essential to meeting climate change goals.

Brown/black hydrogen

is the oldest way of producing hydrogen through coal gasification. The hydrogen is separated from ‘syngas’ using adsorbers or special membranes and is termed brown or black depending on the type of coal used. It is a highly polluting process and all emissions are released into the atmosphere.

What are the by-products of burning hydrogen?

The higher flame speed of hydrogen increases the flame temperature locally, which can generate higher levels of NOx. Burners will be designed that manage the flame temperature and maintain at least parity of NOx levels with today’s natural gas boiler technology.

N.B The combination of Hydrogen (or methane) with air will always generate NOx as a by-product due to the oxidation of Nitrogen from the air mixture.

Although NOx emissions do not directly impact climate change, we know that at high localised levels it is a pollutant which can have health implications and damage vegetation. The Clean Air Act and localised agendas like the London Plan look to keep NOx levels to a minimum in urban areas for these reasons.

Will hydrogen cost more than natural gas?

Today we do not know the future cost of hydrogen to the consumer. Electricity is currently on average three times the cost of natural gas and we know that hydrogen requires electricity for its production. Hydrogen experts are confident costs will improve in the coming years and Ofgem the UK regulator, including economic regulation, has laid out its role to the government in supporting the development of a low carbon hydrogen economy. Low-cost renewable energy will be the most important factor in driving down the cost of green hydrogen in the future.

What’s the difference between 100% hydrogen and 20% blended hydrogen for boilers?


HYDEPLOY is a hydrogen energy project which aims to prove that blending up to 20% volume of hydrogen with natural gas (methane) is a safe and greener alternative to the gas we use today. The main advantage of choosing a 20% upper limit to the hydrogen concentration is that is expected that existing gas appliances, including boilers, can operate without modification. The key technical challenge is developing the grid network to safely inject, monitor, and regulate a 20% hydrogen blend.  This activity is already well underway and ultimately the HSE (BEIS) will approve any change to the Gas Safety and Management Regulations based on the evidence. This will then enable grid operators to inject up to 20% hydrogen into the gas network.

There is already high confidence that a 20% blend of hydrogen is safe for current production and existing installed appliances from laboratory work and the first phase of field trials at Keele University. Groupe Atlantic UK (GA UK) domestic boilers have been part of this trial and run on 20% blended hydrogen gas without any detrimental effect on safety or performance. A more extensive demonstration trial is planned next before finally presenting the full safety case to the HSE.

What’s important to be aware of is that boilers operating on 20% blended hydrogen are still classed as natural gas boilers and will require a conversion to operate on 100% hydrogen in the future.

In the recently released Government Hydrogen Strategy it mentions the 20% blend as having potential to reduce the carbon emissions in the grid by up to 7%.

100% Hydrogen

100% hydrogen refers to gas appliances that can operate on full hydrogen gas, albeit with the fuel index defined as 98% hydrogen in the ‘Hydrogen-fired gas appliances guide PAS4444:2020’ -  98% being the best option to optimise cost and appliance operation. HY4HEAT, is the currently ongoing government-funded programme establishing if it is technically possible, safe, and convenient to replace natural gas (methane) with hydrogen in residential and commercial heating. This will enable the next stage of community trials to proceed.


‘Hydrogen Ready’ is a term associated with 100% hydrogen when used in the UK. A hydrogen-ready boiler is a gas-fired boiler which can burn on either natural gas or via a conversion 100% hydrogen and is seen as a key enabler in the conversion of existing gas networks from natural gas (methane) to hydrogen. 

The current net zero 2050 pathway does not forecast to see hydrogen distribution being onstream until the early 2030s nor at this stage does it define how widespread it will be. ‘Hydrogen Ready’ boilers are currently at prototype stage but will become fully approved appliances in the next few years as regulations and standards are confirmed.

The potential hydrogen hubs in the UK

So, what about the gas network?

The UK is supplied by a single gas network which provides gas to all types of properties and appliances. As a result, any change in gas impacts all appliances connected to it. This includes boilers, water heaters, decorative fires, and cooking appliances. These appliance types cannot be dealt with in isolation. It will be important that competency frameworks and skills are in place for the safe conversion of homes and buildings from natural gas (methane) to hydrogen.

It is likely that we will start with hydrogen production zones in large industrial clusters where hydrogen gas is required for manufacturing. These areas and regions that could have hydrogen are not yet fully identified, nor when hydrogen would eventually become nationally available. The case is being made to mandate for new models of domestic boilers to be hydrogen-ready after 2025, with the case for commercial boilers in discussion. This is to future proof the ease of conversion from natural gas (methane), yet many of these boilers may never run-on hydrogen, certainly within their first product lifecycle.

What papers and policies can you read more about hydrogen and its role in the future of heating?

The following three reports published at the end of 2020 are the UK government and advisors’ first intention of a commitment to hydrogen for heating:

  • The 10 point plan - ‘Plan for a green industrial revolution which will create and support 250,000 British jobs’ (announced November 2020)
  • Climate Change Committee 6th Carbon budget – followed by the announcement that “The government has accepted the advice of its independent Climate Change Committee (CCC) to adopt the emissions cut, which is based on 1990 levels.” Cut carbon emission by 78% by 2035.

And what other changes are we expecting to see to regulations and standards?

  • UK Building Regulations – New Build
    • Building regulations Part L uplift to reduce carbon emissions levels in early 2022 and changes to the fuel and primary energy factors to reflect cleaner electricity
    • Future Building Standard 2025 uplift to significantly reduce carbon emissions further, close to net zero.
  • UK Building Regulations – Existing
    • Changes to appliance regulation for hydrogen-ready appliances
  • British Standards EN437 and EN15502 to include hydrogen information
  • Hydrogen-fired gas appliances guide PAS4444:2020
  • BEIS Hydrogen Strategy – due Summer 2021
  • COP 26 – Nov 2021. The next annual UN climate change conference. COP stands for Conference of the Parties, and the summit will be attended by the countries that signed the United Nations Framework Convention on Climate Change (UNFCCC) – a treaty that came into force in 1994.

What does this mean for Hamworthy products?

As you can see there is no clear path yet and many questions still to be answered. But that does not mean we are standing still, far from it.

Our long-term vision is to support you in selecting the best suited products for your projects, regardless of fuel source. We will ensure a collaborative approach to the energy transition.

With our extensive, UK-based technical expertise in combustion technology, unrivalled market knowledge, and strong customer relationships we are ready to guide you on this hydrogen journey. This puts us in a strong position to continue to provide a complete service package regardless of technology, from design and specification support through to installation, commissioning, service and repair, plus technical training.

Our work towards 100% hydrogen deployment is underway, however you need efficient and affordable heating and hot water today. Plus, it is still important to focus on reducing demand as much as possible and controlling products so that no energy is wasted when operating.

We will continue to provide boilers that work safely, efficiently, and operate safely on 20% hydrogen blended gas, which acts as a great stepping stone in reaching Net Zero by 2050.

Ultimately, we believe there will not be one fuel or technology that will dominate, but a mix. This means you can choose the most appropriate heating and hot water system for your project. And it will ensure the best solution for the country, environment, and your individual building’s needs.

What is the time frame for any changes to hydrogen?

In the latest Government Hydrogen Strategy it states that the Government aim to consult later this year on the case for enabling, or requiring, new natural gas boilers to be easily convertible to use hydrogen (‘hydrogen-ready’) by 2026 – this date is 1 year later than the 2025 date we have been hearing about from the Committee for Climate Change. In addition to residential properties this must also address non domestic (commercial) challenges which are complex and not a simple upscaling exercise. If this becomes policy of course GA UK will be ready.

We anticipate more detail specific to our industry in the Heat and Buildings strategy which is likely to be released after the summer recess and before COP26 in November.

Hydrogen timeline


We’re also leading the commercial boiler discussion, so a clear timescale either aligned or phased to domestic is debated to avoid any unintended consequences to our customers. A date when natural gas appliances can no longer be sold has not yet been committed to, as for petrol and diesel cars, but we may well see this change in the coming months.

As the policy for conversion of the gas grid to 100% hydrogen is developed, in the shorter-term  it is likely the gas grid will permit 20% blended hydrogen within the 2020s to reduce the carbon intensity of our grid.

The good news is that Hamworthy boilers will run on this mix without any modification to the existing technology.