INDUSTRY COMMENT
The challenge of decarbonising existing heat networks
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Pete Mills, commercial technical operations manager at Worcester Bosch Commercial & Industrial, discusses the government’s Net Zero targets and the challenges developers will face when decarbonising existing heat networks
n line with the government’s ambition to achieve Net Zero by 2050, heat networks are a proven scalable option to help meet the UK’s decarbonisation targets in the coming years with heating being a major area
to address. There are several steps that need to be tackled before we will be able to decarbonise existing heat networks. To this effect, work carried out under the government’s Heat Network Efficiency Scheme (HNES demonstrator) identified the common issues but time is not on the industry’s side since government aims to decarbonise all existing heat networks by 2035 which is not a lot of time. Large and small scheme developers will face issues looking into existing heat networks and will need to work around the challenges that will arise during the process.
Optimisation opportunities
Highlighted in the Heat Network Optimisation Opportunities (HNOO) work which funded 21 separate studies, were common themes affecting existing heat networks which had similar solutions. These were not all technical issues though with many being identified around ownership and setup of the schemes. There is quite a difference in the UK between large district schemes and smaller communal heat networks, as we have many more smaller heat networks than larger ones. At an estimate, there is approximately 11,000 communal networks, comparted to 2,000 district heat networks. To help disseminate knowledge of the common issues and how to go about tackling them, the Heat Network Optimisation Guidance (HNOG) initiative has been started. This is intended both for those non-technical operators of heat networks and technical specialists
working in the sector. Using videos and written guidance it is hoped that this can help speed up the process of tackling existing issues within heat networks to get them better prepared for low carbon heat sources.
The number of smaller networks will be a particular challenge to hitting the 2035 target as they have tended to be less well designed and installed. Finding the necessary skilled labour to tackle this challenge could be a barrier.
Issues
It is anticipated that there will be issues around converting both large and small existing heat networks. For instance, some of the earlier heat networks will need to be converted to lower operating temperatures. Improvements will need to be made on the return temperatures and the insulation levels they are getting. The first step to achieve a Net Zero target is to get all heat networks operating more efficiently than they are today. The next step would be to start thinking how we can incorporate renewable technology. In addition, there may be some space challenges with existing heat networks transitioning away from technology such as CHP to air source heat pumps demanding an exterior location. Developers understandably want to maximise the space available to the dwellings
rather than to plant areas, leaving those tasked with transitioning to low carbon technologies having to look for innovative solutions.
Hybrid systems
We might find that where we have difficulties with the schemes, we will need to use hybrid systems to get good decarbonisation levels. We have found that if you have around 40% of the heat load covered by heat pumps then you can cover an excess of 80% of your kWh’s. 80% of the energy is going across to a
renewable source, which will be a way to achieve a reasonable level of decarbonisation on some of these harder to do schemes. Ultimately, it could be that some systems achieve full decarbonisation through a hydrogen gas grid transition in the future. Even though we have been set a timescale of 2035, we will only just see hydrogen start to develop at some sort of level as we approach closer to that date. It will not be nationwide in the UK by then but we anticipate some of these schemes might have to limp along until such time as hydrogen can pick up the load. There may be some schemes that are luckier and in areas where hydrogen will come in earlier then we can directly use them. This is just another angle of what might come into play when decarbonising heat networks.
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