Geothermal Potential Increase Related to Low and Ultra-Low-Temperature District Heating System Application

Abstract

Although high-enthalpy resources are raising main attention among investors looking for high-interest rates, low-temperature geothermal resources are significantly easier to access and occurring more frequently. Thus, in order to increase geothermal heat use worldwide, it is crucial to facilitate the use of geothermal water, even if it does not necessarily depict with “hot” adjective. One of these ways of increasing geothermal energy use is the application of ultra-low temperature district heating systems (ULTDH). When applied, not only so-far neglected geothermal resources may gain in importance, but also even more energy from already exploited reservoirs may be extracted. There are obvious difficulties in LTDH (50 – 55 °C supply temperature) and ULTDH (below 50°C supply temperature, not formulaic so far) implementation. Among them pointed out may be not suitable heating systems in dwellings, yet there are opportunities to mitigate those inconveniences. Main advantages of lowest-temperature geothermal aquifers exploitation are increased the prevalence of geothermal energy use. In this way, local communes may gain an important source of merely mineralised water while creating a central heat source which may easily cooperate with various renewable and waste heat sources. Not negligible is also a limitation of heat loss and potential applicability of the ULTDH system as a heat receiver (cooling network). In the paper, there will be presented crucial obstacles in 4th and 5th district heating generation sourced with geothermal energy, increase of useful energy available from given geothermal reservoirs and increase of country’s area where use of geothermal water would be enabled by application of ULTDH, along with proposed methodology (on example of Poland).