An efficient way to generate power from low to medium temperature solar and geothermal resources

Abstract

Little attempt has been made previously to make use of low or medium temperature heat sources ie. 90-260oC for power generation due to the expected low efficiency which is capped by the maximum temperature of the heat source. The paper presents an efficient way to make use of such heat sources for power generation by integrating the low to medium heat (from solar or geothermal sources) into a conventional fuel fired Rankine cycle power station to boost its power output. Importantly, the low grade heat does not enter the turbine directly to generate power, but is rather used to pre-heat the feed-water. Therefore the temperature of heat sources is no longer the maximum temperature of the power generation cycle and does not limit the conversion efficiency of the low grade heat to power. Through a comparison study between solar or geothermal alone power generation and integration with a Rankine power station, the paper demonstrates the merits of such concept.