Is Switching to a Hydrogen Gas Grid a Viable Option?
With carbon targets in place, the UK is looking for low carbon alternatives to replace the existing system of heating the vast majority of properties using natural gas.
One of the recommended options is to convert the gas network to hydrogen, a highly efficient alternative that produces little to no carbon into the atmosphere. But is switching to a hydrogen network a viable option?
Why switch from natural gas?
Burning natural gas to heat our homes, as more than 80% of homes in the UK do, now contributes a third of total UK carbon emissions. So if the UK is to reach targets of reducing carbon emissions by 80% (compared with the levels in 1990) we need to find an alternative way of heating our homes.
One option is a renewable heating system which, rather than burning gas, takes energy from sustainable sources:
- Air source heat pumps
- Ground source heat pumps
- Solar thermal
- Biomass boilers
Yet, having one of these heating systems installed would come at a cost to the homeowner which is a large hurdle to overcome, even despite energy bill savings and payments through the Renewable Heat Incentive (RHI). Homeowners would also have to learn how to use an unfamiliar heating system.
Another alternative would be switching the gas network to hydrogen.
The Committee on Climate Change (CCC) make recommendations to the government on how best to lower carbon emissions. In a report they released in 2018, the CCC made the case for replacing natural gas with hydrogen, a gas that offers a number of benefits in terms of home heating:
- Highly efficient (1kg of hydrogen can produce as much energy as 2.8kg of natural gas)
- No carbon emissions from hydrogen boilers (only produce water vapour and heat)
- Can be used in existing gas grid infrastructure
- Boilers are a familiar heating system for homeowners, unlike renewable heating systems (heat pumps and solar)
However, switching the entire gas network from natural gas to hydrogen wouldn’t be a simple process. The millions of natural gas boilers currently installed across the UK would need replacing with ‘hydrogen-ready’ units and while this would come at a cost, the CCC stated that it is one of the least costly solutions.
Worcester Bosch revealed their very first hydrogen-ready boiler in 2019, showing the direction that one of the leading boiler manufacturers believe the future of home heating looks like.
The boiler is still compatible with natural gas but after a short visit from a heating engineer it can work on a 100% supply of hydrogen. This means that the unit can be installed ahead of time but is ready should the gas network work make a switch to hydrogen.
Worcester believe that it is essential for new boilers to be hydrogen-ready, stating that any boiler installed from 2025 should be able to heat a home using hydrogen. This date coincides with the introduction of a ban on natural gas boilers being installed into new build homes.
Hydrogen fuel cells
In addition to boilers it’s also possible for a hydrogen fuel cell to provide heating and energy to a home. A fuel cell converts chemical energy from a fuel, in this case hydrogen, as well as an oxidant (oxygen) into a supply of electricity. Heat is also produced during this process which can be used to heat the home.
In one sense, fuel cells are similar to batteries but while there is a supply of fuel and an oxidant, they will continue to generate electricity.
The Viessmann Vitovalor CHP is one fuel cell heating system already on the market.
What is hydrogen blending?
If the gas network were to switch from natural gas to hydrogen, it wouldn’t happen over night. Instead, it’s much more likely that hydrogen would be gradually added to existing gas supply.
Not only would this aid the transition to hydrogen but means that it will work with all existing pipework and appliances.
This is known as hydrogen blending. Even making the existing gas supply 20% hydrogen would in itself help to cut UK carbon emissions by 6 million tonnes per year (the same as removing the emissions of 2.5 million cars from the road).
Trialling a hydrogen network
Towards the end of 2019, HyDeploy launched a trial of delivering a hydrogen blend to properties in Keele, a village in Staffordshire. During the trial, a 20% hydrogen blend is being delivered to 100 homes and 30 faculty buildings.
Cadent, a gas distribution firm involved in the HyDeploy trial, believe that delivering a 20% blend of hydrogen to the entire gas network would be like taking 2.5 million cars off the road – reducing UK carbon emissions by 6 million tonnes.
By the end of 2020, it’s hoped that a new HyDeploy pilot will launch in the north east of England.
Speaking about the trial, Cadent Chief Safety and Strategy Officer, Ed Syson said: “Hydrogen can help us tackle one of the most difficult sources of carbon emissions – heat. This trial could pave the way for a wider roll out of hydrogen blending, potentially enabling us to begin cutting carbon emissions from heat by the early 2020s, without customers needing to change their gas appliances or behaviour.
“HyDeploy could also prove to be the launchpad for a wider hydrogen economy, fuelling industry and transport, bringing new jobs and making Britain a world-leader in this technology. Urgent action is needed on carbon emissions and HyDeploy is an important staging post on that journey in the UK.”
What are the limitations of hydrogen?
First and foremost, hydrogen is currently an expensive fuel to produce. And while hydrogen can be produced in a number of ways, including electrolysis (splitting water into hydrogen and oxygen using electricity) and Steam Methane Reforming (natural gas reacts with steam, oxygen or both), it can emit carbon.
When it comes to hydrogen production through electrolysis the electricity needed would have to be generated through renewable sources (wind and solar, for example) rather than the burning of fossil fuels. It’s possible to capture any carbon emitted during the process of producing hydrogen with Carbon Capture Storage (CSS) systems which would prevent the carbon from being released into the atmosphere.
While the production produces carbon, once delivered to the boiler, hydrogen won’t release any carbon into the atmosphere.
Find out more in Hydrogen Boilers: An Alternative to Gas Central Heating?.
So, is hydrogen a viable option?
According to industry experts, hydrogen has a major role to play in the future of home heating but it can’t be the only solution.The ideal low-carbon heating system for homes of the future would include a renewable heating system, powered by electricity, alongside a hydrogen boiler.
Unfortunately, hydrogen production is currently very expensive and those costs are one of the things standing in the way of the solution that currently holds the most potential for decarbonising the UK gas network.
Should the hydrogen trials around the UK go successfully then that will only strengthen the case for a hydrogen network.