Author: The Institution of Engineering and Technology IET
The UK is investigating supplying hydrogen to homes and businesses instead of natural gas by “repurposing” the gas network. It presents a major engineering challenge which has never been done anywhere else in the world.
In a new report titled ‘Transitioning to hydrogen’, experts from a cross-professional engineering institution (PEI) working group, including the IET, have assessed the engineering risks and uncertainties and concluded there is no reason why repurposing the gas network to hydrogen cannot be achieved. But there are several engineering risks and uncertainties which need to be addressed.
What are those engineering risks and uncertainties?
Hydrogen experience is limited to industrial applications only and there are no examples of networks anywhere in the world supplying 100% hydrogen to homes and business. To make a significant contribution to meeting the UK’s 2050 GHG (greenhouse gas) target, large-scale deployment to homes and businesses would need to be implemented over the next 30 years. This is ambitious and so any decision to proceed will need to be sufficiently compelling to compensate for the lack of experience and comparatively short timescale.
The report identifies 15 core questions that need to be addressed before large-scale deployment can be achieved.
Why hydrogen for heating?
Although natural gas has helped reduce the UK’s CO2 emissions by displacing coal and oil (which produce around twice as much CO2), it has now become the largest source of carbon emissions in the UK:
40% of electricity generation is from gas
85% of homes are heated by gas
50% of the energy used for industry and businesses is from gas
When combusted, hydrogen produces no CO2 and so it offers the prospect of a low-carbon alternative to natural gas. Repurposing the existing gas network to pure hydrogen could contribute significantly to the decarbonisation of the UK and reducing the current dependency on natural gas.
Other factors that make hydrogen a strong alternative to natural gas include:
Hydrogen allows much of our existing gas infrastructure to be used
Most of the local “iron mains” gas network will have been replaced with polyethylene pipe by 2030, which can be used with hydrogen. This means most of the necessary street works would have already been done.
Hydrogen can be used by industry, businesses and homes
Existing gas boilers in the home will need to be replaced but this can be facilitated by future sales of “hydrogen-ready” gas boilers, which can be readily converted to hydrogen. Many industrial applications should be able to convert from gas to hydrogen, although others may require blending with biomethane, for example.
Hydrogen can be produced in large volumes
Production from gas reforming has been used by industry for years, but a by-product is CO2, which needs to be captured and stored. Modern reforming technology can have high CO2 capture, but experience is limited. Hydrogen can also be produced from electrolysis but the power would need to come from renewable energy sources, which is likely to be higher cost.
Hydrogen compares well with other low-carbon heat technologies
The diagram compares the primary heating technologies suitable for large-scale retrofit deployment against several criteria. While the comparison is subjective and generalised, it is not meant to indicate that one form of heat technology is “better” than another but to illustrate the different features and to highlight the potential benefits of hydrogen. A full explanation can be found in the report.
The report’s recommendations are that we:
Progress CCuS infrastructure – CCuS (carbon capture, utilisation and storage) infrastructure is essential to the bulk production of hydrogen.
Deploy critical new technology – New technologies will need to be deployed for which there is limited experience. “Learning by doing” is essential to ensuring robust cost and performance data.
Prepare a transition programme – This needs to include sufficient detail to ensure the identification of critical path items and their associated uncertainties. Assumptions will need to be underpinned by evidence and where evidence is not available, it will need to be sought.
Develop skills and plan resources – Transitioning to hydrogen will require a broad range of skills and resources. Mobilising these resources will necessitate the commitment from many parties.
Fund the programme – The transition programme will require substantial investment over many years. A stable funding regime needs to be assured, underpinned by central and local government policy in conjunction with Ofgem and other regulatory parties.