Decision paths to reduce costs and increase economic impact of geothermal district heating in Geneva, Switzerland

Abstract

Geothermal district heating could play an important role towards climate change mitigation, but its slow uptake implies that it is cost competitive only under specific sets of conditions, including drilling success and design of the district heating. Even in cases when geothermal district heating may be less cost competitive than other alternatives, expenditure that occurs during its development brings indirect economic impact that could also benefit domestic economy. Using the case study of the State of Geneva in Switzerland, this paper analyzes cost competitiveness and economic impacts of 5′892 decision paths (combinations of decisions) to develop geothermal district heating, including the choice of auxiliary heat source, and uses comprehensive sensitivity analysis to identify the most influential decisions. The right share of geothermal coverage in the heat mix to achieve an optimum combination of investment costs and geothermal heat production, and the integration of waste incineration as auxiliary heat source are crucial for cost competitiveness. High economic impact multipliers are created by geothermal systems incorporating individual pellet boilers as auxiliary heat source. High share of domestic impact consistently occurs in the case of standalone geothermal installations, especially when they are used with second or third generation of district heating. Combining geothermal district heating from medium and deep wells (1′500 m and 2′500 m) with heat from waste incineration creates synergies where above-average cost competitiveness and economic impacts are achieved.