Comparative analysis of potential district heating systems in older urban neighborhoods - A case study in Benoordenhout, The Hague
Summary
The Dutch government has adopted ambitious targets to decarbonize the heat supply of the built environment. For this, key focus lies on building heat demand reduction and for the supply of renewable heat, a district-oriented approach is handled. For older urban neighborhoods, extensive building retrofits to reduce heat demand are often very expensive or legally restricted, making low-temperature heat systems unfeasible. District heating systems operating on a medium-temperature level (MT DH, ~70 ºC) can be a solution for such neighborhoods. Several potential heat sources for MT DH can be identified, such as heat from surface water (TEO) or wastewater (TEA) upgraded by large-scale heat pumps. Seasonal thermal energy storage in aquifers (ATES) can be used to improve the energy potential of these sources. Geothermal energy can also provide heat at the same temperature level. To assess and compare the district heating potential of these sources, a case study is performed on the district of Benoordenhout in The Hague. The heat demand of this district by 2030 was modeled using simulation data for different types of houses, under the assumption that only cost-efficient insulation measures are applied. The local heat potentials of TEO, TEA, ATES and geothermal energy were estimated using a range of tools. Data on capital and operational cost of heat technologies and DH infrastructure were obtained and integrated into an energy model, together with expected trends on prices of natural gas and electricity. Six heat scenarios were developed and compared to a reference scenario of individual gas boiler use. It was found that geothermal energy has the potential to cover the entire annual heat demand of Benoordenhout, and can be even larger by implementing a heat pump to the return flow. Connection to the cities’ existing DH system is required to cover peak demand. The levelized cost of heat (LCOH) is found to be lower than for the reference scenario, and the project can yield substantial profits. The potential of TEO and TEA as heat sources for Benoordenhout is very limited. The LCOH in all scenarios is much higher than the reference LCOH, and the net present value (NPV) of the projects is negative. This is mainly due to high costs of DH infrastructure. TEO and TEA could become viable heat sources when DH infrastructure is already in place. For consumers, it is not financially attractive to connect to a district heating system under current regulations.