Production of systems that use the heat of the earth (or ocean) to produce usable heat for industrial purpose or power generation. New developments include hot dry rock (hot fractured rock HFR), enhanced geothermal systems (EGS) with deep artificially drilled sources and the use of (abandones) oil wells. Due to the nature of geothermal systems which contain less patent-protectable technology (than solar cells for example) this category also contains related heat exchange systems and the drilling operation itself. Geothermal power plants provide pollution-free baseload power unlike more intermittent sources like solar and wind power. The expensive drilling operation (e.g. in 4km depth) and controlling underground water flow are among the most challenging tasks for geothermal systems.---Important Specifications---Type of geothermal systemHeat carrier and cooling system (efficiency, toxicity etc.)Underground/Water temperature needed (water temperature, temperature difference earth, water, cooling)Connection to power gridAvailability of drilling resource
