Martyn Bridges, Director of Technical Communication and Product Management at Worcester Bosch, discusses some alternative technologies to hydrogen and heat pumps which can contribute to net-zero 2050.
Preparations for net-zero 2050 are well and truly underway. Having spoken a lot about how hydrogen solutions and heat pumps will contribute to decarbonisation, it is worth turning the conversation to some alternative and some existing technologies and how they have an either short or long term part to play on the road to zero carbon emissions.
These technologies include bio-oil-fired boilers and Heat Interface Units (HIUs). While somewhat overshadowed in conversations surrounding decarbonisation, both are important solutions in the bid for net-zero.
So, how can we use each of these technologies and how are they best used for decarbonisation?
Oil boilers will not be familiar to the majority – in the UK, some 23 million homes have a gas-fired central heating system, while only 1.2-1.3 million have oil-fired heating. They are usually found in rural or hard to reach areas.
They are a minority in comparison but, from an urgency perspective, targets concerning oil-fired boilers are the first the Department for Business, Energy & Industrial Strategy (BEIS) have in its sights.
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
HIUs look similar to a boiler: 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 apartments or houses where the HIU is sited.
Therefore, they are technology or fuel agnostic. 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.
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