If not heat pumps or hydrogen – then what?

We have recently shared a poll on LinkedIn to see what you think the alternative to gas boilers will be, in response to the IEA’s report stating that gas boilers should not be sold from 2025. Here, Martyn Bridges, director of technical communication and product management at Worcester Bosch explores alternative technologies to hydrogen and heat pumps which can contribute to net zero 2050.

Oil boilers

In the UK, around 23 million homes have a gas-fired central heating system, while only 1.2-1.3 million have oil-fired heating. Most often, they are found in rural or hard to reach areas.

Martyn Bridges says: “In 2018, it was stated in the Clean Growth Strategy that oil-fired boilers were to be banned in newbuild properties. There is talk about then addressing oil in the million or more existing homes these homes are mainly in remote areas where gas is not available, and in old properties or even listed ones which are difficult to insulate or renovate. To substitute oil with anything else is a tough challenge.

“The government hopes that heat pumps will be the technology to save the day here – in fact, a scheme will begin on 1 April 2022 offering a £4,000 grant to help homeowners swap their oil boiler out for a heat pump. While to some, such a suggestion seems encouraging, but in fact it is somewhat impractical due to the extreme changes that will need to be made in the home and the likely inconsistency of a suitable and powerful enough electrical supply in many of these rural areas.

“One option is ‘greening’ the oil using HVO, a hydrogenated vegetable oil. In the past we have conducted oil-greening trials with an alternative called FAME, but HVO provides a more accepted alternative as its constituents are from a far more favourable source.

“We are involved in a HVO trial with OFTEC where 10-15 sites are running on this oil which is zero carbon throughout its lifespan.

“I hope that BEIS and government will consider such alternatives alongside electric heating, perhaps by greening the oil to a 100% or even a lower blend, while supplementing any shortfall with low emission technology such as an air to water heat pump and solar water heating.

“As such, oil heating systems can be decarbonised with a high blend of HVO rather than having the entire heating system swapped out for the only other alternative on the table.”

Heat Interface Units

Heating Interface Units (HIUs) look similar to boilers although there is no flue or gas supply as they take heat from a central tank or calorifier store of heated water. This is then distributed into the residence where the HIU is sited.

Discussing how HIUs are technology or fuel agnostic, Martyn says: “It does not matter where the hot water comes from or how it got hot. In different schemes, some have been heated by heat pumps or biomass boilers, while the majority are unfortunately still heated by gas-fired boilers. So, while they are not totally carbon neutral now, they can be.

“There have been some creative solutions to this, particularly in London where large amounts of high-density housing and tower blocks have the calorifier is heated using waste heat from the underground tube network via a heat pump. One particular site I visited in Wakefield, is using a 3,000 litre calorifier, heated by a biomass boiler to provide the heat and hot water to a social housing site of around 120 homes with back up in the shape of a gas-fired boiler in case.

“The government have, in my opinion, a perhaps over ambitious belief that HIUs will be used on around 20% of the housing stock, that is around 4m homes. I think that is very optimistic as the investment is very high.

“However, in new tower blocks and apartments, it makes sense to use the technology. The investment is high, but it is worthwhile. Using a heat pump, solar thermal, or even with hydrogen to heat these calorifiers offers a great solution for these high-density housing situations.

“In summary, while conversations surrounding decarbonisation tend to focus on hydrogen solutions and heat pumps, other technologies have a lot to offer on the road to net-zero 2050.”

Have you been asked about HVO alternatives to gas boilers, or HIUs? We’d love to hear from you stephanie@renewableenergyinstaller.co.uk.