Potential for use of heat rejected from industry in district heating networks, GB perspective

• 4 to 7 TWh/yr of waste heat could be supplied to GB district heat networks under central assumptions.
• To use 75% of industrial waste heat, requires transmission up to 45 km to heat demand densities of 1.5 MW/km2.
• Effects of heat losses and potential for heat-driven heat pumps are less significant.
• Seasonality of demand tends to increase need for auxiliary heat sources.

District heating schemes can act as enablers for the use of low carbon heat sources. Heat rejected by industrial sites could potentially be used in supplying such schemes but various constraints limit the extent to which this is likely to occur. This study estimates the quantity of heat that could be supplied to district heating networks from industrial sites in Great Britain (GB), in the context of a range of limiting criteria. An existing spatially disaggregated database of GB's heat demands was combined with previous analysis of the magnitude, temperature and location of the heat that is rejected by industrial sites. The heat that could be supplied from the industrial sites to the heat demands was then calculated with a range of different criteria applied. The criteria which were considered included the maximum allowable distance between the heat sources and demands, the minimum heat density of the demands which was considered feasible, the heat losses that may occur, and the seasonal profile of the heat demands. The potential gains from using absorption heat pumps, driven by high temperature heat to supply lower grade heat were found to be limited. High and low estimates of the heat rejected by the industrial sites were compared. Domestic and non-domestic heat demands were examined. Although the domestic demands have a greater total, they tend to occur at lower densities and so it is likely that both demands will take a significant share of the heat supplied. The seasonality of the heat demands has a greater impact on the need for supplementary heat sources than on the total heat delivered. For the distance and heat demand density criteria considered most appropriate, only half of the heat which is rejected by industry could be utilised by district heating networks.