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How Does Hydrogen Boilers Work, Cost, Benefits, and Disadvantages?


There is a mix of excitement and uncertainty surrounding hydrogen boilers, the newest technology in the UK heating industry. The news that the government is planning to ban gas boilers in favour of hydrogen boilers has also fueled homeowners’ curiosity towards this new technology.

In this guide, we will discuss all there is to know about hydrogen boilers, beginning with their feasibility, when they are expected to hit the residential market and how they are expected to work. The guide will also examine the costs, benefits, and disadvantages of this new tech. So make yourself comfortable as we take a deep dive into the hydrogen boiler world.

The Rise of the Hydrogen Boiler

With global warming continuing to take a toll on world climate, the UK government seeks to reduce greenhouse emissions in the country by 80%. The government aims to achieve this milestone by 2050. And to get there, it plans to ban natural gas boilers from 2025. The decision to ban gas boilers is well-informed, considering natural gas usage currently accounts for about 17% of the country’s carbon footprint.

Banning natural gas boilers will force households to turn to low carbon heating alternatives, including heat pumps, biomass, solar, and hydrogen boilers.  And among these low carbon heating solutions, the government is currently championing the hydrogen boiler that is both renewable and environment friendly.

To show its commitment to this new heating solution, the government has already launched a pilot scheme that has seen two homes in Gateshead, London, fitted with hydrogen boilers. The next phase of this hydrogen project will be unveiled in early 2022, where over 300 homes in Fife, Scotland, will be connected to the hydrogen gas grid.

As this is a relatively new technology, the first 100% hydrogen boiler is yet to be produced. However, industry giants such as Worcester Bosch, Viessmann, and Baxi have finished developing prototypes that are already in the testing phase. Worcester Bosch and Viessmann have also rolled out hydrogen-ready boilers that accept a mixture of hydrogen and natural gas in the ratio of 20/80.

The good thing about hydrogen-ready boilers is that they are compatible with the existing infrastructure for natural gas. This means the transition to hydrogen fuel will be smooth and reasonably priced since these boilers will be using the existing gas grid and engineers.

What is a Hydrogen Boiler?

A hydrogen boiler is a boiler that burns hydrogen gas to heat water for central heating and domestic use. There are essentially three variations of hydrogen boilers that are currently being designed. The first is the hydrogen-only boiler that will use pure hydrogen from a grid to heat water.

The second type is the hydrogen-ready boiler, which is essentially a gas boiler compatible with hydrogen fuel. These boilers are designed to use a mixture of both hydrogen and natural gas but can be altered to use 100% hydrogen in the future. The good thing about hydrogen-ready boilers is that they can continue running on natural gas until hydrogen gas is available. This means that the entire country can gradually transition to hydrogen fuel without disrupting home heating.

Lastly, there is the hydrogen fuel cell boiler which uses an onsite hydrogen cell to generate renewable electricity for heating hot water. The hydrogen fuel cells undergo a chemical reaction to produce heat and electricity. The heat generated by the hydrogen cell boiler can be used to heat the house, while the electricity can be used to power electronic gadgets. This will be a great alternative, especially where it is impossible to get piped hydrogen gas into a house or commercial property. The first hydrogen fuel cell boiler is the Viessmann Vitovalor that costs between £10,000 and £15,000.

How Does a Hydrogen Boiler Work?

A hydrogen boiler works similarly to natural gas boilers. When the boiler is ignited, it takes the supplied hydrogen gas and burns it to create hot flue gases used to heat water for central heating and domestic use. A storage tank is usually installed together with the boiler and stores the hot water, which can later be pumped around the pipework in your property.

That said, here is a more detailed explanation of how a hydrogen boiler works.

  1. Oxygen and hydrogen enter the boiler’s combustion chamber

Oxygen and hydrogen, the two gases needed for combustion, enter the boiler through the gas inlet. In this case, oxygen is drawn from the air while hydrogen is supplied through the main gas supply pipe. The gas inlet has a control valve that helps regulate the amount of each gas that enters the boiler, therefore determining the size of the flame.

  1. The gases are ignited in the catalytic burner

The two combustion gases are mixed and then ignited to produce combustion gases. And since hydrogen is a highly flammable gas, the boiler is fitted with a unique burner that can automatically limit the size of the flame if there is excess hydrogen gas from the outlet. It also has a flame detection component since hydrogen flames are invisible.

  1. Hot gases from the combustion chamber enter the heat exchanger

The hot gases from the combustion chamber are forced into the heat exchanger, which is essentially a series of pipes in contact with the cold water pipes. As the hot gases travel through the heat exchanger, it heats the surrounding water, which is then pumped into the hot water cylinder in your home.

  1. Combustion by-products exit the boiler

Just like any fuel, hydrogen produces some gaseous by-products after undergoing combustion. But since hydrogen is a clean fuel, it doesn’t produce carbon dioxide but instead produces water vapour. The water vapour is then condensed and drained via the condensate pipe.

Hydrogen boilers are also fitted with a flue that provides an escape route for the hot flue gases, in this case, oxygen, hydrogen, and some traces of NOx.

Despite the similarity in operation, hydrogen boilers still differ from conventional gas boilers in that it has a slightly different flame detector and burner. Some internal components of the hydrogen boiler are also expected to be different from that of its predecessor.

Advantages of Hydrogen Boilers

Lower (or zero) carbon emission

The most significant benefit of hydrogen boilers is that they are an environmentally friendly heating solution that leaves the smallest possible carbon footprint. Unlike fossil fuels that release carbon dioxide as a by-product of combustion, hydrogen burns completely to produce heat and water, none of which is harmful to the environment. Therefore, switching to hydrogen boilers will go a long way in reducing global warming.

Hydrogen is a renewable energy source.

Although hydrogen makes up only 0.00005% of the atmosphere, it can be extracted from water, biomass, and natural gas, meaning it is an inexhaustible energy source. This means that hydrogen is enough for everyone in the world, and we can tap on it to power all kinds of appliances without depleting the reserves.

There is no need to replace the existing gas infrastructure

The shift to hydrogen energy doesn’t necessitate the laying of new infrastructure as it has been established that hydrogen can be distributed using the existing gas infrastructure. Since the government isn’t required to install any new infrastructures, the hydrogen scheme can be rolled out as soon as trials have been approved.

Hydrogen fuel is more efficient than fossil fuels.

Researchers have found that hydrogen is a richer and more efficient energy source than natural gas. They also found that hydrogen is more compact and stores double the energy as the same amount of fossil fuels. In fact, one kilogramme of hydrogen can produce the same amount of energy as two or three kilogrammes of natural gas. This means that you can use less hydrogen fuel to heat your home.

Leaks are non-toxic

Hydrogen can be found in our everyday environment, ranging from the water we drink to the food we eat and the air we breathe. In other words, hydrogen is harmless and can’t impact your health like nuclear energy and natural gas. Moreover, hydrogen combustion doesn’t produce any harmful gases, meaning you won’t have to worry about any dangerous gas leaks in your home.

They speed up the use of renewable energy sources.

To stay true to its cause of carbon neutrality, the government is seeking ways of producing hydrogen gas using electricity produced from renewable energy sources. This means that the switch to hydrogen gas will see an increase in offshore wind generation and the use of solar energy. The government plans to ramp up offshore wind generation by at least four times by 2030 to support hydrogen production.

They have similar technology and systems to gas boilers

Hydrogen boilers are easy to operate are they are designed to work the same way as the typical gas boiler. This means homeowners won’t have a steep learning curve once they switch to hydrogen heating as they can operate the new technology with relative ease.

Hydrogen fuel is easy to store

Unlike nuclear energy that needs to be stored in radiation-proof containers, hydrogen gas can be compressed, liquefied, and stored in special containers. However, hydrogen storage won’t be necessary in most cases as it is expected to be delivered directly to your hydrogen boiler.

Hydrogen heating would create thousands of jobs

The switch to hydrogen energy will generate 9,000 new jobs by 2030, and this number is expected to leap to 100,000 by 2050. Some of the opportunities that will be made available by this new technology are research roles, engineering roles, and installation roles, among others.

They cost just the same as gas boilers

The big boiler manufacturers have promised homeowners that hydrogen boilers will be reasonably priced and will cost almost the same as natural gas boilers. This means that households won’t have to break the bank to acquire and install a hydrogen boiler.

Disadvantages of Hydrogen Boilers

Like any boiler or fuel, hydrogen boilers and hydrogen fuel have disadvantages. Some of the drawbacks of this new technology include:

Hydrogen production is expensive

Researchers are yet to discover a cheap and sustainable way of producing hydrogen, considering that the existing hydrogen extraction techniques are expensive and consume a lot of electricity.

The first method of hydrogen production is steam-methane reforming, which involves reacting methane and steam to produce hydrogen as a by-product. The issue with this method of hydrogen production is that it depends on fossil fuels and leaves a carbon footprint.

The second method of producing hydrogen is electrolysis which involves splitting a water molecule using electricity to produce hydrogen and oxygen. Although this method is environmentally friendly as it uses electricity, it is pretty expensive as a lot of energy is required to perform the electrolysis process.

The high hydrogen production costs discourage many countries from investing in hydrogen energy. Nonetheless, researchers are working tirelessly, conducting researches and trials to determine a new hydrogen extraction method that will be cheap and won’t impact the environment. And until the day they make a breakthrough, hydrogen would remain unviable for mass production.

Hydrogen is highly flammable.

Hydrogen is highly volatile and flammable due to its high energy content. Moreover, since the gas doesn’t smell, it becomes a risky fuel to store and use in your home, as detecting a gas leak is almost impossible. Some researchers have even claimed that hydrogen boilers are three times more likely to explode than gas boilers, casting doubts on the safety of hydrogen as a domestic fuel.

The production of hydrogen leaves a carbon footprint

There is no debating the potential of hydrogen boilers in lowering carbon emissions. However, producing hydrogen by the Steam Methane Reforming (SMR) produces carbon, defeating the purpose of carbon neutrality. Luckily, it is possible to capture and store the produced carbon using the Carbon Capture Utilization and Storage (CCUS) system.

Fortunately, electrolysis is an environmentally friendly solution powered by renewable energy sources like solar panels and wind turbines.

Hydrogen is more difficult to store and transport than natural gas

Hydrogen gas is less dense than air, meaning it must first be compressed under high pressure and stored at low temperatures. The high pressure required to compress the hydrogen gas means it will be difficult to transport large quantities of the fuel.

Existing gas infrastructures need to be altered

Although hydrogen-ready boilers can work well with existing natural gas appliances, an overhaul has to be done before you can use 100% hydrogen fuel. This is particularly important considering that hydrogen and natural gas have different burning properties.

Hydrogen energy cannot sustain the whole population

Although hydrogen is a renewable energy source that is plentiful in supply, the cost of tapping it is expensive, making companies shy from investing in it. Moreover, households across the country are yet to be fitted with a heating infrastructure best suited for hydrogen fuel. And this means that even if producing hydrogen were to become cheap right now, people won’t still be able to use it. In that regard, it will take years before hydrogen can usurp fossil fuels from being the king of the UK heating industry.

How Much Would Hydrogen Boilers Cost?

It is difficult to determine the price of a hydrogen boiler at this point since the first batch of hydrogen boilers have yet to hit the market. However, top boiler manufacturers have hinted that the hydrogen boiler will cost just as much as the current gas boilers. Going by the recent market figures, it is easy to assume that it will cost you anywhere between £1,000 and £4,000 to purchase a new hydrogen boiler.

Where Do I Store the Hydrogen Fuel in My Home?

It is no secret that hydrogen, a volatile and highly flammable gas, can be dangerous when not handled carefully. However, there is no need to worry about handling or storing hydrogen fuel for a hydrogen-ready boiler as the hydrogen will be supplied to your home directly via the UK gas network.

When Are Hydrogen Boilers Expected To Be Available?

With gas boilers set to be banned on newly built properties from 2025, it is safe to assume that the first hydrogen boilers will be ready by then. However, the transition to hydrogen energy will be done in phases so as not to disrupt the existing heating infrastructure. But how exactly will this be implemented?

For the first phase, the boiler manufacturers are expected to roll out hydrogen-ready boilers that can accept a combination of natural gas and hydrogen. These boilers are expected to be ready from 2025 onwards and should be designed to be easily modified to run on 100% hydrogen.

The second phase is whereby new hydrogen gas will be blended with natural gas and rolled out using the existing gas grid. This phase is expected to be implemented sometime after 2028.

Lastly, phase three of the project is whereby all UK households are expected to be using a hydrogen-only boiler. This is perhaps the most challenging part of the project and is expected to be completed in a few decades.

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