Awareness of the need to cut greenhouse gas emissions to reduce the impact of climate change is reaching mainstream media. Recently, schoolchildren and young people in the UK have taken part in climate strikes urging that action is taken (See Guardian 15 Feb 19, Climate strike: UK school pupils take part in call for urgent action). The Committee on Climate Change (the CCC) has also suggested, in a recent report, “UK housing: Fit for the future?“, that new homes built after 2025 should not be connected to the gas grid and that instead heat pumps should be used for space and water heating. Banning boilers may be one approach to the problem but it is not the only option.
This article explores whether hydrogen offers another solution that could enable homeowners, business and the government to together reduce carbon emissions. BEIS report that in the UK around 17% of greenhouse gas emissions are from homes, for space and water heating (BEIS: 2017 UK Greenhouse Gas Emissions). So what steps can be taken?
1. Improve Your Home’s Energy Performance
Action: Homeowner, Timescale: Immediate
This should be at the top of everyone’s carbon reduction list, irrespective of debates on which future carbon reduction technologies to choose. Tackling heat loss from your home is a highly effective way of reducing both your impact on the planet and your heating bills – and it can be done today. Reducing heat losses involves:
- Making sure the insulation levels are the best they can be (improving U-values of floors, walls, ceilings as well as windows and doors).
- Eliminating draughts to reduce ventilation losses (this is measured with an air tightness test which will tell you how much air leaks from your home).
- Making sure moisture levels and air quality are the best they can be for a healthy home (MVHR systems can help: read more about MVHR).
- Ensuring your home is still a pleasant temperature in the hotter summers that seem to be coming our way.
Whilst individual heat loss measures can be done in isolation, considering the whole building provides the best overall solution. Improving the U-values of floors, walls and ceilings as well as reducing cold draughts and improving air quality can make a huge difference to the overall wellbeing of those living in the house. Whilst costs are significant, converting the typical house to the Passivhaus standard can reduce space heating energy requirements by upwards of 80% (For details on Passivhaus see Great Home -Energy Efficient Homes).
2. Add Hydrogen to the Gas Grid (upto 20%)
Action: Gas Suppliers and government, Timescale: 2020-2025
Currently, the maximum hydrogen content of the UK grid is 0.1% (molar) but one project in the UK (HyDeploy) has been granted permission by regulators to explore adding upto 20% hydrogen to the grid. Current evidence is that existing appliances can cope with burning this level of hydrogen without adjustment. By burning more hydrogen, the carbon emissions from your boiler will be automatically reduced.
Producing the huge amount of hydrogen needed for the gas grid may involve using fossil fuels and require Carbon Capture and Storage (CCS) systems. However, a better solution long term is if the hydrogen is produced using renewable electricity and an electrolyser, which is what the HyDeploy project will use (read about the HyDeploy technology) As more and more renewable energy sources are added to the electricity grid, there will be times when more electricity is generated than is required for immediate use and storage batteries can soak up some of this excess for short-term use (0-24 hours). However converting this excess energy into hydrogen and storing it in the gas grid provides longer term options for inter-seasonal energy storage.
3. Convert Gas Grid to 100% Hydrogen
Action: Gas Suppliers, Timescale: 2028-2034
A switch to 100% hydrogen from natural gas has already been explored with the H21 Leeds City Gate project. This assessment project concluded that:
- The gas network has the correct capacity for such a conversion
- It can be converted incrementally with minimal disruption to customers
- Minimal new energy infrastructure will be required compared to alternatives
As a result of the initial project, a new project, H21 North of England, has been proposed. This contains a detailed engineering solution to convert the gas network in the North of England, covering 14% of the gas network, to 100% hydrogen over the 2028-2034 period. It includes inter-seasonal storage of hydrogen in salt caverns able to deliver 8TWh of energy and sequestration of 20Mt per year of CO2. (Read more about this project at the Northern Gas Networks website). It is assumed that consumer appliances such as gas boilers and cookers would either be converted or replaced . There is a separate Hy4heat demonstration project which will look at hydrogen appliances which should give a better indication of how easy it is to convert. Individual boiler manufacturers will also be exploring solutions to upgrading to 100% hydrogen.
Having a 100% hydrogen network also creates other opportunities:
- A small hydrogen fuel cell could be used to generate electricity for use in the home, especially at time of peak electricity demand, as an alternative to using the electricity grid.
- A wider availability of hydrogen for refuelling of hydrogen fuel cell vehicles; this is likely to be a commercial opportunity rather than domestic because of the high pressures (350-700 bar) used in refuelling fuel cell vehicles.
Whilst there are a number of options for decarbonising UK domestic heating systems, the key priority has to be to reduce the energy demand for space and water heating. Hydrogen at the 20% or the 100% level in the gas network could play a significant future role if the projects described above are implemented as planned.