Hydrogen Boilers: An Alternative to Gas Central Heating?
We know that we can’t go on using fossil fuels to power our vehicles, generate our electricity and heat our homes, but what are our alternatives? Wind, solar and hydro power are going to be a big part of the fight against climate change, but they aren’t necessarily the answer to the question of central heating.
We need to find an alternative to the gas network, but is hydrogen the answer?
Why do we need an alternative to gas central heating?
Not only are fossil fuels running out, but the continued use of them is emitting greenhouse gases such as carbon into the atmosphere. These gases cannot escape our atmosphere, causing temperatures across the globe to rise which is changing our climate. The world is at risk and it is now an urgent and international concern as, if allowed to continue, it will have disastrous consequences for our planet. As part of the worldwide climate emergency, the UK government is working towards reducing the country’s carbon emissions. Specifically, the UK needs to reduce its carbon emissions by 80% by 2050 (compared to 1990 levels). To do this, we need to adopt renewable energy systems for electricity and heat generation.
Heating contributes around a third of the UK’s total carbon emissions so finding an alternative fuel and technology would reduce our carbon footprint significantly. The UK government has already introduced measures to improve the energy efficiency of gas boilers, phase out the use of oil boilers and from 2025 it will be illegal to install a gas boiler in a new build.
However, currently, 8/10 homes in the UK use gas boilers to fuel their central heating. Using renewable energy rather than fossil fuels would reduce our country’s carbon emissions significantly. This means we need to install alternative renewable heating systems in 80% of the UK’s homes.
What’s the alternative?
There are several renewable technologies which can provide low-cost, low-carbon and sustainable heating and hot water including air source and ground source heat pumps, solar thermal and biomass boilers. While these are viable options for many homes, many industry experts are concerned about the impact switching to these systems would have on homeowners. The systems are unfamiliar, often costly to install and are only effective in well-insulated properties. To avoid asking homeowners to part with their boilers and spend money on new technology, it may be better to replace not the boilers we use, but the gas they run on. In theory, this means using the existing gas network with a low carbon gas rather than natural gas.
There are several ‘low carbon’ gases which are already being used as alternatives to natural gas such as biomethane but we cannot produce this gas in high enough quantities to meet demand. According to many industry experts, a hydrogen network is the most viable.
Low or zero carbon emissions
When our boilers burn fossil fuels carbon is released into the atmosphere which is damaging our planet. When hydrogen is burned, it produces only water and heat with no carbon. Even if we were to use a combination of natural gas and hydrogen, we could significantly reduce carbon emissions.
No need to replace infrastructure
A hydrogen network could use the same pipelines, fittings and boilers as natural gas so there would be very little need to invest in changing the infrastructure. Even if the switch happened today, many boilers could stay in use and homeowners could avoid the costs involved in replacing a heating system.
Highly efficient fuel
Hydrogen contains a lot of energy as 1kg of hydrogen contains the same amount of energy as 2.8kg of gasoline.
Challenges of hydrogen
Hydrogen production is expensive (at the moment)
Producing hydrogen in large enough quantities to meet demand is not cheap at the moment. Hydrogen can be produced either by electrolysis, i.e. using electricity to split water into oxygen and hydrogen, or by Steam Methane Reforming (STR).
Hydrogen production can emit carbon if not captured
Although hydrogen won’t emit carbon when used by a boiler, producing hydrogen can emit carbon. To tackle this issue low-carbon production methods need to be developed. For example, electrolysis would need to be powered by renewable electricity from wind or solar farms rather than electricity produced by burning fossil fuels.
SMR involves heating the methane in natural gas with steam and a catalyst, but this produces carbon as well as hydrogen. To make this method low-carbon, Carbon Capture Storage (CSS) systems need to be used to prevent the carbon from escaping into the atmosphere.
Testing the hydrogen theory
There are projects around the world trying to find an efficient way to produce low-carbon hydrogen.The UK government has invested £20m in the Hydrogen Supply Programme to investigate how viable a hydrogen network would be. This includes the HyDeploy project at Keele University. The project is trialling the use of 20% hydrogen with 80% natural gas on a private gas network without changing the pipelines or boilers. A 12 month trial is due to begin in summer 2019.