Hydrogen for Heating?
by David Cebon – 28 September 2020
The most frequently proposed ways to heat buildings in a low carbon future are using hydrogen to power hot water boilers or electricity to power heat pumps. There are two ways to make hydrogen: these are known as ‘green’ (using electrolysis) and ‘blue’ (using steam methane reformation). This article compares the various options on the basis of energy efficiency, carbon emissions, infrastructure requirements and technology readiness.
The key conclusions are:
- Heat pumps are far more efficient than green hydrogen for heating buildings. The ‘wind-to-heat’ energy consumption of heat pumps is 1/6 that of green hydrogen, for delivery of the same amount of heat. Therefore the energy generation costs for heat pumps are 1/6 of those for green hydrogen.
- As a consequence of the inefficiency of the green hydrogen route, it would require an inordinate amount of renewable electricity to heat the UK’s buildings: approximately 40 times the current installed capacity of offshore wind. The heat pump route would require significantly less additional renewable electricity.
- The blue hydrogen route for heating buildings would require a 25% increase in the amount of natural gas imported into the UK, taking the imports to 60% of national consumption. This would be detrimental to the balance of trade and energy security.
- Neither the green hydrogen nor the blue hydrogen route is ‘clean’. Both generate substantial carbon emissions. In 2020, the green hydrogen route emits 50% more carbon than burning natural gas in a condensing boiler.
- Blue hydrogen will always generate significant ‘fugitive’ CO2 emissions, that escape into the atmosphere. Consequently, use of blue hydrogen for heating would prevent the UK government from meeting its legal commitments for ‘Net Zero’ emissions by 2050.
- Heat pumps generate 1/4 of the emissions of a natural gas boiler in 2020 and this will reduce significantly with time as the electricity grid becomes cleaner. They are the most effective way to reduce carbon emissions from heating. Heat pumps are available off-the-shelf, now.
- It is unlikely that the infrastructure needed for blue or green hydrogen could be built in time for 2040.
- Government policy should promote the of use of heat pumps for heating new and retrofitted buildings, and should reject hydrogen as an option for heating.
The push towards use of hydrogen for heating is misguided. Burning hydrogen is very inefficient compared with the alternatives. Consequently hydrogen is wasteful of renewable electricity and would substantially increase the amount of natural gas used in the country. The carbon emissions caused by burning blue or green hydrogen are significantly higher than those of heat pumps. It is unlikely that the infrastructure needed for a hydrogen economy could be built by 2040.
Hydrogen is a fundamentally poor choice for heating buildings. It should not be on the agenda. A far better strategy is to convert the country's heating systems to heat pumps. This should be government policy.
These (above) are the principal conclusions of David Cebon's blog. For the full blog, including detailed arguments supported by detailed calculations and a full set of references, we recommend a visit to David Cebon's full blog.