Conditions for deep geothermal energy utilisation in southwest Latvia: Nīca case study

This paper focuses on the deep geothermal energy utilisation from the Lower Cambrian sandy siltstone aquifer as a potential supply to the district heating system in Nīca, a small municipality in southwest Latvia. Based on this case study, we argue that it is technically and economically feasible to develop efficient geothermal heat stations in small municipalities rich in geothermal resources under three key preconditions: sufficient extractable heat resources of the aquifer; ready availability of a nearby deep well; and – a plan for environmentally acceptable disposal of the cooled geothermal water to the surface waters. If these conditions are met, the deep geothermal energy utilisation in a small-scale district heating system might be economically viable and possibly more sustainable than a larger district heating system, where high-pressure re-injection of the cooled geothermal water into deep rock aquifers is necessary.