The amount of energy stored in a geothermal reservoir depends on amount of mass and type of material in the reservoir, e.g., water for conventional geothermal power generation or rock for enhanced geothermal systems, EGS). Generally, the temperature of the material needs to be a minimum 150 oC to be considered for power generation. a) Compare the thermal energy available in a water reservoir (c = 4.184 kJ/kgK, = 1000 kg/m3) with the thermal energy available in a rock reservoir (c = 2 kJ/kg K, = 2600 kg/m3), if both reservoirs are located between 8 and 10 km below a surface area, A, and if both reservoirs have the same thermal gradient in the vertical dimension