Hydrogen Boiler explained

An introduction to hydrogen boilers

Once they reach the market, hydrogen boilers will be capable of burning 100% hydrogen gas. With the potential to efficiently produce heat for homes across the UK, hydrogen boilers act as a clean energy alternative to fossil fuels and natural gas. 

Whilst the transition to hydrogen isn’t expected for several years, it should be a fairly simple swap once some of the logistical and technical issues are ironed out. There is currently a need for carbon-neutral methods of producing mass amounts of hydrogen, and the technology to be used in new hydrogen boilers is yet to be developed. Once these challenges have been overcome, the UK’s existing gas infrastructure can be used to deliver the environmentally friendly, highly efficient new source of fuel.

How are hydrogen blend or Hydrogen-ready boilers different?

Hydrogen blend/ready boilers are the first step to securing the zero-carbon alternative to heating homes. Manufacturers are focusing their efforts on introducing hydrogen ready boilers rather than 100% hydrogen boilers. This aligns with the government’s plans to phase in the fuel alternative rather than making an instant transition.

By 2028, it is expected that hydrogen will be introduced into the energy supply as a ‘blend.’ Upon commencement of the first phase of this transition, 80% natural gas is to be combined with 20% hydrogen. Predictions suggest that this 20% reduction of natural gas in heating systems will generate the same reduction in emissions as taking 2.5 million cars off the road.

What about hydrogen fuel cells?

Rather than combustion, hydrogen fuel cells convert hydrogen into electricity and heat during a chemical reaction. With water being the only waste product of the chemical process, these low carbon alternative batteries produce clean energy for several applications.

Industries such as transportation have actively introduced the use of hydrogen within cars and vehicles. The fuel source guarantees efficiency and zero emissions. Developments have also been made in domestic heating. The Viessmann Vitovalor CHP generates up to 18 kWh of electricity per day using hydrogen fuel cells and is highly efficient at heating water. Despite its numerous benefits, the cost to replace boilers nationwide with this type of system would be far too expensive. 

Why is there a need for an alternative fuel source?

Since the introduction of gas boilers in 1868, fossil fuels, including natural gas, have been used to heat water for taps and central heating. This continual combustion of natural gas to heat our homes contributes to 19% of global greenhouse gas emissions. Within the UK alone, central heating produces one-third of carbon emissions. 

Not only are fossil fuels non-renewable and running out, but the release of carbon dioxide into the atmosphere is damaging the planet. Greenhouse gases cannot escape the earth’s atmosphere and trap heat from the sun, which causes a temperature rise, changing the earth’s climate. 

Overwhelming attention has finally been directed toward the global climate crisis. The UK along with many countries across the globe have pledged to reduce carbon emissions and limit their impact on climate change. Goals to reduce 75% of greenhouse gas emissions by 2035 and reach net-zero carbon emissions by 2050 have produced the urgent need for a sustainable, carbon-free heating solution. This is where hydrogen boilers have an important part to play. 

Why Hydrogen?

Low carbon alternatives to natural gas have been suggested. Installing solar thermal panels or a heat pump provides carbon-free heat and electricity. However, replacing gas boilers in every home throughout the country would be impractical, time-consuming and incredibly expensive.

Rather than replacing the heating system, the focus has been placed on alternative fuel sources. Hydrogen gas, when produced cleanly, is a highly efficient energy carrier that only generates water as a waste product. It is even more fuel-efficient than natural gas as an energy source. 1kg of hydrogen releases the same energy as 2.8kg of natural gas. For lowering carbon emissions, burning hydrogen instead of natural gas appears to be an ideal solution.

Why can’t we use 100% hydrogen boilers sooner?

Hydrogen is one of the planet’s most abundant resources, and there are plenty of methods of producing more. However, due to the delay in logistics and infrastructure, the technology needed to supply hydrogen gas to homes across the country is years from being fully integrated. 

One of the core factors preventing the replacement of current gas boilers is that to produce hydrogen, a method of mass production that isn’t carbon-intensive needs to be developed.

Steam methane reforming (SMR) is the procedure that is currently used to generate most of the hydrogen fuel consumed within the UK. It is significantly carbon-intensive and relies on unsustainable fuel sources. Due to the limitations of this procedure, the replacement of current gas boilers has halted.

The SMR process harnesses the products of a reaction between natural gas, steam and a catalyst. Unfortunately, hydrogen is not the only product of the reaction; carbon monoxide is also produced. Unsustainable amounts of natural gas are required for the reaction, increasing rather than reducing carbon emissions. 

Predictions have suggested that the technology to produce clean hydrogen gas won’t be available for another ten years. However, this hasn’t prevented the government from continuing to trial hydrogen and pursuing the boiler upgrade scheme. At the current rate, the goal is to introduce a hydrogen and natural gas blend into the mains supply by 2025. This will mark the beginning of the transition to a much cleaner energy source.

How hydrogen ready boilers work

Hydrogen gas and natural gas create slightly different reactions when combusted. However, this won’t require significant changes to the components of hydrogen ready boilers. The addition of certain features will accommodate the requirements of burning hydrogen, but the overall process of generating heat remains the same. 

Once hydrogen gas is introduced, the blended fuel will be supplied using the existing gas network. This gas will enter the boiler and combine with oxygen before heating to combustion via a catalytic burner. As a result of this combustion, hot flue gases will enter the heat exchanger. This includes a series of pipes surrounded by cold water. As the hot gases travel through the pipes, the surrounding water is heated to be sent to the tap or travelled around the central heating system. Hot flue gases exit via a flue with small amounts of NOx emissions generated during combustion.

Accounting for a much lighter and flammable gas, hydrogen ready boilers need to be fitted with specific burners, which limit the flames should too much gas enter the system. Additionally, hydrogen produces invisible flames when burnt. Therefore, flame detection components will be implemented within the hydrogen boiler.

When transitioning from natural gas to hydrogen blend fuel, gas registered engineers, plumbers and boiler installers will complete the relevant training to become acquainted with the components of new hydrogen boilers. Boilerhut installers will efficiently complete hydrogen blend and hydrogen boiler installations. Our team is always equipped with up-to-date training and expertise.

Benefits

• Cleaner energy

Burning fossil fuels to generate heat creates massive amounts of carbon as a waste product. This carbon is released into the atmosphere, causing detrimental effects on our climate. 

When produced cleanly, hydrogen’s waste products include water and minimal amounts of nitrous oxide. The switch to this fuel would have subsequent positive effects on the current climate crisis. In the coming years, just switching 20% of our current gas supply to hydrogen will present monumental reductions in carbon emissions.

• No need to overhaul existing infrastructure

Fortunately, the existing pipelines and infrastructure used to transport and supply natural gas can be repurposed. Instead of rebuilding the entire system, some modifications to the existing infrastructure will save significant expenditure and prevent additional carbon emissions that may have been produced during the construction process.

• Cheaper bills

Hydrogen is a far more efficient fuel than the natural gas currently used within boilers. As an efficient energy carrier, it will take significantly less fuel to produce enough heat for one house. Due to the reduction in fuel consumption, domestic bills should drastically decrease. 

The unsustainability of natural gas is one of the key factors that constantly drives energy prices. As seen with the current gas supply in 2022, the inability to procure resources increases prices exponentially. With established production and transportation routes, efficiently produced hydrogen fuel sources would significantly decrease domestic prices.

 Disadvantages

• Extremely flammable

The hydrogen element consists of just two hydrogen atoms attached via one proton and one electron. This simple chemical structure makes it light in mass, odourless, non-toxic and extremely flammable. 

Compared to natural gas, the use of hydrogen does pose a higher risk when ignited. Boiler manufacturers will therefore implement safety mechanisms to reduce the risk. Excess flow valves are one of these mechanisms. It controls the release of gas into hydrogen boilers to prevent excess amounts from causing ignition risks.

• Difficult to store and transport

Cost and practicality are two of the main concerns associated with the transportation and storage of hydrogen gas for domestic use. To be condensed into a liquid form for transportation and storage, 1.01 of pressure and a temperature of -257.87℃ need to be achieved. 

Compared to natural gas liquefaction, a reduced pressure of 0.25 bar and temperature of just -162℃ is required. Liquefication of hydrogen consumes up to 30% of it’s energy content, and the process is expensive. Research into improved technology for hydrogen liquefaction is required to provide a more efficient and cost-effective process. 

• Expensive to produce

There are two standard methods of producing hydrogen used for the mass market. These include SMR and electrolysis. Currently, these processes are either unsustainable or ill-suited to provide the quantity of hydrogen needed for the purpose of heating water within homes.

SMR is the process of combining steam and natural gas with a catalyst. This is currently the most widely used process for the production of hydrogen. Electrolysis is a carbon-free alternative that uses electricity to split water into hydrogen and oxygen. Currently, this procedure is only suited for small scale production rather than meeting the demands of the entire country. 

When will hydrogen boilers be available in the UK?

There are several challenges concerning production, transportation, and hydrogen utilisation to overcome before the switch occurs. As it stands, 100% hydrogen ready boilers are not yet available on the UK market. 

However, significant progress has been made by manufacturers Worcester Bosch, Viessman and BAXI. Hydrogen blend ready boilers are now available for purchase and installation today. 

Due to the logistics and development associated with the integration of hydrogen into our energy supply, the UK government has laid out a timeline for particular milestones to be achieved. 

Phase 1: By 2025, all boilers should be built and available at a hydrogen ready standard. Whilst they will be capable of operating using natural gas initially, modifications will allow these heating systems to transition to 100% hydrogen fuel. 

Phase 2: 20% hydrogen blend will be introduced into the energy supply. This adjustment is not expected until 2028, providing homes with gas boilers the opportunity to acquire a hydrogen boiler. 

Phase 3: Eventually, the gas network throughout the UK will be transitioned to 100% hydrogen fuel. Due to the significant developments that need to be made before this change, the switch is not expected to happen before 2040. 

How much will a hydrogen boiler cost?

Whilst there aren’t currently any commercial models of hydrogen boilers available, a price promise made by four boiler manufacturers has provided an idea of the expected cost. Worcester Bosch, Vaillant, Baxi, and Ideal have formed a joint initiative concerning the development of hydrogen ready boilers. 

The initiative has confirmed that new hydrogen boilers will not cost more than the natural gas equivalent. This is expected to save consumers billions of pounds and demonstrates the manufacturer’s dedication to the zero-carbon solution.

Combi and system gas boilers typically cost between £600-900 for a budget model, £900-1200 for mid-range spec, and £1000-2000 for a premium boiler. Whilst these prices are likely to fluctuate and change, the cost of a new hydrogen boiler won’t significantly exceed these price brackets. 

Installation is another cost that needs to be considered when purchasing a hydrogen boiler. Due to the similarity in ancillary components, accessories and controls, the installation process won’t be dissimilar to natural gas boilers. Regulatory change mandating will require gas registered engineers to be fully trained in their installation, and hydrogen boilers will quickly become a high volume technology. This will reduce the cost to no more than installations for typical gas boilers.