The National Infrastructure Commissions new report says that ‘heat pumps should be the dominant electrified heating solution. They are highly efficient, available now and are deploying rapidly in other countries. For every unit of energy paid for, a heat pump can generate around three units of heat (by ‘pumping’ heat from outside into the house), whereas a fossil fuel boiler generates less than one unit of heat per unit of energy paid for’.
There is certainly a widespread view now that they are better than hydrogen for home heating. And, on the basis of its analysis, the NIC asserts that ‘there is no public policy case for hydrogen to be used to heat individual buildings. It should be ruled out as an option to enable an exclusive focus on switching to electrified heat’.
It notes that ‘there is growing evidence that heat pumps are suitable in a wide range of building types. The government has stated that 90% of homes already have sufficient energy efficiency and internal electrical connection capacity to accommodate a heat pump. This aligns with evidence that buildings with an energy efficiency rating (EPC) D or above, which make up 90% of English homes, are likely to have a peak heat loss rate that makes them suitable for heat pumps with minimal to no energy efficiency improvements. Peak heat loss rate is important as it impacts the effectiveness of a heat pump. In the share of the 10% of homes which would need at least some energy efficiency improvements, there will be a proportion where these improvements could be costly. Installing high temperature heat pumps could be more cost effective for these homes than carrying out extensive energy efficiency improvements’.
However, the NIC does admit that ‘heat pumps will be challenging to install in space constrained buildings. The most common heat pump systems require a hot water tank which requires space. Around 10% of English homes may not have space to add a hot water tank’. But it says, ‘other forms of thermal storage, like heat batteries, that take up less space, could be combined with a heat pump, and innovation continues to bring new options to the market’.
So it still backs heat pumps. ‘Delivering decarbonised heat will be a challenge under all scenarios. But there are unique challenges in scenarios with hydrogen heating that make it a worse option. The process of switching buildings from a natural gas to a hydrogen supply must happen at the same time for multiple buildings’ and ‘already having a hydrogen compatible boiler’ won’t help avoid this.
The NIC does note that are some negatives for heat pumps and positives for hydrogen. It says, while heat pumps use around three times less energy than hydrogen boilers to produce heat, they have higher upfront in-building installation costs, and hydrogen heating reduces the direct use of electricity and peak electricity demand from heating -but also increases overall demand because (more) electricity is used to produce hydrogen. It also notes that ‘electricity demand for hydrogen production through electrolysis will affect the unit cost of electricity and the availability of ‘spare’ (i.e. curtailed) electricity will impact the cost of hydrogen production’ and it says, while hydrogen heating requires ‘a more extensive system of hydrogen pipelines and additional storage’, having no hydrogen heating ‘requires more decommissioning of the natural gas network’. Even so, taking all this into account it concludes that, given policy changes that it proposes, ‘a system with hydrogen heating would be 1.2 times more expensive than one without’.
So that’s seen as a clear win for heat pumps for heating. But it’s not by that much, especially given that there are many uncertainties, so perhaps NIC’s assertion that hydrogen should be ‘ruled out’ for heating in favour of heat pumps exclusively is a bit too strong. After all, the NIC do note that ‘for some buildings, low carbon heat networks will be the best option, rather than individual heat pumps. Heat networks should not be put at a disadvantage. The same amount of subsidy per household or small business should be made available for developing heat networks, via the current Green Heat Network Fund capital grant or similar’. NIC doesn’t say, but could be that hydrogen may be used to make some of the heat for heat nets too, depending on location.
Of course there are also other end uses for hydrogen, apart from building heating, including for decarbonisation in industry. The NIC recommends that for use like this ‘a core hydrogen network connects the most likely initial sites of hydrogen demand, production & storage’. It adds ‘there are many industrial sites across the country that are not in industrial hubs. Some of these dispersed industries could use hydrogen but have not been prioritised in outlining an initial core network because demand is less certain. These sites could produce hydrogen locally or switch to electricity. Parts of the transport sector could also use hydrogen. Hydrogen can be tankered to refuelling stations or produced locally and therefore does not depend on the availability of a core network’.
NIC do seem to want to avoid repurposing the existing fossil gas network! Maybe they worry that if it’s left, there will be a temptation for it to be used for fossil gas! Hydrogen may not be the answer to all things, but if we can avoid using fossil-derived ‘blue’ hydrogen, and stick to zero carbon green hydrogen, then it may still have many useful roles, and so might the gas mains, suitably upgraded. And heat nets, solar heating and biomass heating too- as well of course as the increasingly widescale use of domestic and industrial heat pumps!
As I noted in my last post, the debate on green heating is far from over, with for example, a study for gas company Cadent by Imperial College London suggesting that adopting hydrogen for heating homes, supplied through the gas network, could yield annual savings of over £5 billion, compared to using electric heat pumps. The debate goes on...
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