This study collects, analyses and maps data relating to previous district heating (DH) feasibility studies in Scotland. District heating feasibility study data, obtained primarily from industry stakeholders, was analysed to identify common barriers restricting district heating development and to map study locations. This research aims to support emerging national district heating policy and to enhance the Scottish Heat Map.

We analysed 44 studies, which comprised a total of 76 proposed district heating schemes. We also undertook an additional high-level review, and mapping, of a further 33 ‘in development’ schemes that were included in the Scottish Government’s ‘Low Carbon Heat Database’. Therefore, a total of 109 proposed district heating schemes were reviewed and mapped.

It is worth noting that data collection from stakeholders was severely hampered by the Covid-19 pandemic.

Key scheme characteristics
  • Scheme viability: When considering the 76 proposed schemes that were reviewed in detail: 46 proposed district heating schemes were reported by the authors as being viable and 22 schemes were reported as being unviable (with circa 37% being reported to be financially unfeasible). No assessment of viability was reported for the remaining eight schemes.
  • Property mix: When considering the 109 schemes: 68 schemes (62%) explored the feasibility of serving a mix type of buildings (domestic, commercial and/or industrial); 29 schemes (27%) explored the feasibility of serving domestic buildings. Ten studies (9%) explored the feasibility of serving commercial buildings. Two studies (2%) explored the feasibility of serving industrial facilities.
  • Main heating technologies: 33 schemes were based on a gas-fired combined heat and power (CHP) system; 22 schemes were based on biomass boilers; and 13 schemes did not specify a proposed primary heating technology.
Key barriers

Semi-structured interviews with eight key stakeholders identified the key barriers that the stakeholders believed to be restricting the development of district heating schemes in Scotland, including:

  • high capital costs and long payback periods of district heating projects;
  • high demand risk (payback period being dependent on consumer demand);
  • lack of district heating technical knowledge and skills in the industry;
  • lack of investment interest and lack of investor involvement in the process;
  • lack of realistic business cases and delivery/procurement models; and
  • lack of stakeholder and consumer awareness and lack of stakeholder buy-in.
Recommendations
  • The Scottish Government may wish to consider carrying out further research on the financial and technical shortcomings identified in individual district heating network projects. This in turn could provide the opportunity to validate the key findings of this report.
  • The Scottish Government may also wish to consider investigating ways in which district heating feasibility studies (e.g. particularly those studies that receive government support) can be analysed and reported in a consistent manner to enable a greater level of cross-comparison between schemes.

Scotland has committed to achieving net-zero greenhouse gas emissions by 2045. Heat is at the core of Scotland’s energy system, accounting for approximately half of the energy consumed by homes and businesses. This makes heat the biggest element of Scotland’s energy use and its largest source of emissions. The Scottish Government (in line with advice from the Committee on Climate Change) has identified heat networks, or district heating, as one of the ‘low-regret’ options – low cost and with relatively large benefits – for heat decarbonisation. Its Climate Change Plan 2018[1] (CCP) focuses on significant reductions in emissions from buildings, both residential and non-domestic.

This study supports the emerging regional and national policies associated with the development and deployment of low-carbon heat networks (or district heating) by examining potential waste heat sources in Scotland that have received limited attention. Heat networks, or district heating, involve providing heat to homes and businesses via insulated pipes in the form of hot water or steam.

 The study assesses the waste heat potential of 10 different sectors (distilleries, breweries, bakeries, paper and pulp, laundry, supermarkets, data centres, electricity substations, waste-water treatment plants (WWTP), and landfill) using a variety of data sources and calculation steps.

 Waste heat potential:

  • The study has identified a waste heat potential of circa 1,677 GWh across some 932 sites in Scotland. 
  • The largest waste heat potential was estimated to be in the distillery and waste-water treatment sectors. Bakeries and paper and pulp are the other sectors with high waste heat potential.

Opportunities:

  • Data centres, breweries, supermarkets, laundries, bakeries and paper and pulp sites have relatively high heat demand in their local areas. As a result, these may provide potential for district heating (DH) opportunities.
  • 237 sites (equivalent to 25% of all the waste heat sites we identified, with a total waste heat potential of 146,554 MWh), have an existing DH scheme within 500m.

Recommendations:

  • Further investigation is recommended on the technological aspects of waste heat recovery from WWTPs, distilleries and paper and pulp mills, as these sectors have relatively higher theoretical waste heat potential. 
  • There is a need to review and assess the heat recovery technologies suitable for capturing waste heat from electricity substations. 
  • The viable distance for the distribution and use of waste heat will vary depending on several factors. Further research in this area and/or reviews of the technical and commercial aspects of recovering and re-using waste heat in district heating systems would be advantageous.
  • As only a simplified proximity analysis was undertaken, it would be advantageous to conduct additional analysis to explore the opportunities for supply / demand matching in more detail.