Why hydrogen is not the best method of decarbonising heat

Hydrogen might not be viable to heat our homes, says Twinn Sustainability Innovation’s Chris Twinn FCIBSE

Hydrogen (H2) is often touted as a viable solution to meeting UK net-zero carbon targets. However, the London Energy Transformation Initiative (LETI) has published a report that finds it unlikely that zero carbon hydrogen – supplied via a repurposed gas mains network – will be available for the vast majority of buildings in the foreseeable future. We asked the report’s lead author Chris Twinn to explain.

Isn’t H2 an obvious route to decarbonisation as we already have a gas infrastructure?

Unfortunately, we do not have all the infrastructure needed, aside from the local yellow polyethylene distribution network. The large steel, high-pressure primary distribution network is likely to need replacing or upgrading. As hydrogen is a manufactured gas, large-scale manufacturing plant (typically methane reformation) has to be built, with access to the natural gas raw material. Large-scale carbon capture and storage (CCS) is needed to capture the manufacturing carbon emissions. Additional carbon sequestration is also required, because CCS only captures 90% of CO2 emissions, as is large-scale hydrogen storage. Think those demolished gasometers – only three-times larger in volume.

Won’t a switch to H2 be as simple as the town to natural gas change?

Records show this switch was far from smooth; Hansard details numerous complaints raised by members of parliament on behalf of their constituents. The switchover was beset by poorly trained and insufficient numbers of engineers, and identified many latent defects in existing gas installations and appliances, which building owners had to put right themselves. Consequently, many homes had no heating, hot water or cooking for extended periods. It should also be noted that this was a region-by-region switchover programme, enforced on all building owners/occupiers – so no choice on timing or convenience. With no social media at the time, most personal experiences and the impacts on the more vulnerable have been largely lost in time. What politician would commit to such a national rollout process today?

Doesn’t carbon storage solve hydrogen’s CO2 problem?

Currently, this is a fledgling technology with no examples at anything like the scale needed for a national gas grid switchover. Along with all the associated technology needed to make it work, exceptionally large investment would be needed. However, our gas supply has been a low-cost commodity, without large profit margins – or, indeed, the electricity ‘green crap’ levy – to pay for this level of investment. To put this in perspective, the suggested investment needed is in the order of magnitude of NHS spending for 20 years.

Will hydrogen be cheaper?

Hydrogen is a manufactured gas expected to be made from natural gas. So, it costs what natural gas does, plus the added cost of manufacture. Adding, say, 50% to the wholesale gas price would add about 25% to the consumer price. This does not include the switchover and new infrastructure costs. Amortising the suggested total switchover cost would increase the gas price by something like 300%. A heat pump has the potential to deliver the same heat using one-third of the quantity of delivered energy.

What about hard-to-heat stock that’s not easy to insulate for heat pumps?

The switch to heat pumps will be challenging for certain building types. However, there are many heat pump variants, heating system adaptations, and insulation intervention combinations available. New complementary technologies are also emerging – for example, phase-change thermal stores of a size that can replace a combi boiler. As a nation, we are new to heat pumps and there is much we should be learning from others who have already built up their experience, such as Japan. Regarding the hard-to-heat driving us to a full hydrogen switchover: who is prepared to pay the large switchover costs just to benefit a sub-sector of the market? 

Is there any future for hydrogen in decarbonising energy supply?

Probably, as a more limited-use, higher-cost premium fuel, pitched at a level to pay for more modest switchover costs. There is talk of localised hydrogen hubs for certain industries that need high-temperature heat. Off-grid buildings may use it as a substitute for propane or oil, and there is interest for serving long-haul aviation. Long-distance road haulage appears to be going cool on it, because of a lack of refuelling infrastructure. There is testing for remote rail lines, but with the proviso that the infrastructure costs are less than electrification. Perhaps most importantly for our sector, harnessing hydrogen’s seasonal storage abilities seems plausible, created using future summertime excess wind-turbine capacity and this fuelling power stations to boost winter electricity peak capacity.