Potential solutions for the decarbonisation of the UK's heat network

The government must develop a more comprehensive heat policy. The main issue with decarbonising heat is the lack of direction on how best to proceed. Reducing emissions from the heating network needs to be based on two factors: reducing demand and decarbonising the supply.

There are numerous potential solutions to decarbonising the supply to the heating network:

energy efficiency

This is the first step towards the decarbonisation of heating. With regards to reducing demand, we need to improve the energy efficiency of homes through retrofitting existing homes and setting higher standards for new builds. Zero Carbon Homes was a policy which almost went ahead in 2015 but was scrapped at the last minute. This policy would have cut emissions from new homes to zero. You can read a briefing on this policy from ECIU here.

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Increasing the supply of low carbon gases in the network:

  • Currently, the supply of low carbon gases, such as biomethane and hydrogen, make up a tiny proportion of the heating supply. When combusted as a fuel, hydrogen only releases water. Hydrogen can be produced via electrolysis (from water using an electric current) or conversion from methane. However, for the latter to be carbon-neutral, it requires carbon capture storage technology.
  • Hydrogen can be used as a gas itself or blendedwith existing natural gas supplies (see Keele University Hydeploy). The UK used to have a greater quantity of hydrogen in its gas mix that it currently permits (called town gas). Presently we permit less than 1% hydrogen to be in our gas supplies, whereas other counties allow a greater quantity with no adverse effects and lower emissions. 
  • Increasing their supply would mean less reliance on high carbon emitting sources.
  • Injecting biomethane into the gas grid is a means of decarbonising supply without requiring changes from consumers. However, its potential is limited to around 5% of gas consumption (CCC).
  • National Grid has estimated that per annum enough gas to meet 20-33% of domestic gas demand from BioSNG and biomethane. *
  • These methods are just low carbon sources and they do still emit some CO2.
  •  Such a shift must be supported by all of the network companies so that their assets don’t become worthless.

In May 2018, plans for the first large scale hydrogen power plant were announced, predicted to supply heat for thousands of homes in the North West of England. The plan, which hasn’t yet secured funding, proposes storing the carbon captured during the hydrogen extraction process in the gas fields in Liverpool Bay. It is estimated that this project, HyNet, would provide £17 billion to the northwest’s economy and provide over 5000 jobs, as well as saving over 1 million tonnes of C02 emissions. These proposals are still in discussions with the government and Ofgem, so you could ask your MP to show support such initiative.

*Terminology

BioSNG: synthetic natural gas from biomass.

Biomethanea naturally occurring gas produced through the anaerobic digestion of organic matter.

 Image Source:  The Energy Challenge

Image Source: The Energy Challenge

Electrify the heating network by installing heat pumps:

Heat pumps are powered by electricity and move heat from the ground or the air into the home. They are the leading low carbon option for buildings not connected to the gas grid. There is potential for them to be rolled out to buildings connected to the gas grid also. 

Given that it is easier to decarbonise the electricity network, providing heat by using electricity could be effective to reduce emissions from heating- they are currently suitable in around 10 million homes connected to the gas grid (CCC). Heat pumps are very expensive, costing roughly double the price of a new boiler.

The Energy Saving Trust estimates that heat pumps can lead to significant annual bill savings when replacing a variety of older boiler systems (with effective insulation measures in place). However, they can lead to slightly higher bills compared to the latest fossil-fuel boiler models.

Combined Heat and Power (CHP):

CHP captures heat that is used in the energy generation process. In conventional ways of generating electricity, large volumes of heat are wasted so this is a much more efficient process. In fact efficient ratings of CHP plants can reach 80% and above. In today’s coal and gas-fired power stations, up to two thirds of the overall energy consumed is lost in this way. Read more.

Increase the use of district heating:

District heating schemes, often referred to as ‘central heating for cities’ or neighbourhoods, consist of networks of insulated pipes used to deliver heat, in the form of hot water or steam, from the point of generation (usually a local energy generation centre) to homes and businesses.

These systems are efficient and low cost because they can make use of waste heat from electricity generation. However, less than 20% of UK heating needs can be fulfilled in this way

District heating requires a certain density of heat demand in order to be economic, making them more suitable to urban areas (CCC). Copenhagen has one of the most successful systems in the world, with many benefits: it cuts household bills by 1,400 EUR annually, and has saved Copenhagen district the equivalent of 203,000 tons of oil each year, amounting to 665,000 tons CO2.

The diagram below provides a simple explanation. Underground pipes carry hot water from the local energy centre into homes. A Heat Interface Unit (HIU) gives users the same control over hot water as they would have had with a boiler.

Both CHP and District Heating are both cheaper options than heat pumps, but their implementation on a large scale would require large initial cost and disruption to lay the pipes under the roads. Care in installation is especially important, to ensure that future transitions are still possible to say hydrogen conversion.

There are also potential knock-on benefits from pursing different heat pathways, i.e. pursuing hydrogen for heat could lead to more widely (and cheaply) available hydrogen which could in turn help in the increase of hydrogen cars. Your MP may be interested to hear of these wider benefits.

Date of Publication: 20.06.2018