Across the UK and SPEN licence area, residents are willing to use their local generation to power heat pumps, which would help balance the network, in turn helps to tackle fuel poverty and decarbonise. However, the LV networks are not designed with ample capacity to carry the new load and meet aspirations for LCT penetration. Many residences are hard to retrofit in terms of energy efficiency and space heating. Installing individual heat pumps in terraces, with narrow frontages often without direct road access is difficult. Laying higher capacity HV and LV cable, in congested streets, is expensive, time consuming and disruptive to residents. Therefore, managing constraints and using as much local power as possible, locally, will help run the network as efficiently as possible.
Benefits
a) Reduction in space heating decarbonisation costs for residents in the scheme.
b) Less disruption to residents reinforcing the network.
c) Income stream for community flexibility infrastructure.
d) A solution to the ‘just transition’, allowing disadvantaged communities to access the benefits of low carbon and flexibility markets.
e) Lower capital investment requirements in rural LV networks.
Learnings
Outcomes
- Stakeholder engagement: Multiple stakeholder engagement events have been carried out during the project to gather the key data for the project. From this, a spreadsheet tool was developed that could be used by other communities to gather similar data on a granular basis that could be fed into strategic planning. This is at TRL 6-7.
- Detailed Design Report: The report focuses on installation of communal heat pump and storage (centralised and could be fed from both hydro generations). The report also explores an ideal location for thermal storage and electric battery. The report details the battery arrangements to bypass network constraints in two different ways and reduced import and export onto the 11kV network. One arrangement is utilising a mechanical interlock, and another is by utilising a 11kV B2B VSC. The 11kV B2B VSC could be an efficient means to not only manage constraints further up the network but also improve the resilience of the network. This design could be used in several different scenarios to manage constraints and improve resilience not just for heat networks. This is at TRL 4.
- The CBA conducted, showed there is benefit recorded on the environmental and societal front. There is substantial benefit to a DNO from a heat network from avoided network reinforcement, as the DNO wouldnot be investing in the heat network (it will be funded by third parties). Even where there is no constraint, reduced import and export to the 11kV network frees capacity. The arrangements also increase resilience.
Given this benefit, there should be a means for DNOs to incentivise heat networks, particularly when they balance against local generation. Current flexibility contracts are not suitable for these high capital long term projects. One route for DNOs to incentivise them is via changes in Use of System charges.
Ownership of the 11kV B2B VSC /interlock would need to remain with the DNO although it would be possible for third parties to own the storage. There could be a contract for the DNO to be able to call on/control the storage when it is need for flexibility services and optimise for the heat system at other times. However, the normal running of the storage is likely to help avoid the need for this.
The finding of the network constraint analysis:
- Baseline scenario: This case study was conducted without considering any additional load on the network. We found that there no capacity overloading on all the four substations considered.
- Option 1: This case study was conducted considering 1 kW heat pumps on all individual houses. Three of four transformers have shown no capacity overloading, while one substation showed a capacity loading of 119.5%.
- Option 2: This case study was conducted considering 1 kW heat pumps on 50% of properties and 4kW additional load for direct heating on rest 50% of properties. Two of four transformers have shown no capacity overloading, while two substations showed a capacity loading of 192.8% and 109.8%, respectively.
These were compared with actual heat pump data. The peak demand is not the only concern but also how long the demand is high but at not peak demand (e.g. the number of hours at 90% of peak) is also important.
Lessons Learnt
- More accurate and frequent data granularity is required to carry out effective network analysis. For future scenarios, LV network monitoring data, including for pole mounted secondary substations will be needed for accurate investment planning decisions.
- Many other solar installations that have not been registered with the DNO, the householder does not know the details and/or the installer is no longer available. This means the standard recording method is difficult for them to use retrospectively. A means to record solar installations where the details of the connect have been lost is needed, so that DNO at least knows an installation is present.
- Early engagement with network planning teams, would support understanding of relevant technical requirements to adopt new running arrangements and help ensure that community engagement information is presented in a format that is useful for strategic planning.
- Delivering an innovation project, alongside community engagement and an innovative heat network initiative, can introduce dependencies on parallel activities, these timelines are hard to predict and further slack within the project should have been factored into the project plan; projects operating across both innovation and stakeholder engagement can also present challenges within the current innovation framework.
- The project identified that current flexibility contracts are unsuitable for high capital long term projects developed by third parties but that benefit the network.
