Energy, Exergy and Economic Evaluation and Analysis of Different Temperatures Geothermal Energy Coupled with Biomass-Fired CHP Plant

New geothermal power generation systems for integrated coupling of medium and low temperature geothermal energy at different temperatures and biomass-fired CHP plant is designed and put forward. The system integrates geothermal energy into the biomass-fired CHP plant, replacing part of the steam extraction from the turbine to increase power generation. Under the 110 °C medium-temperature geothermal water coupling scheme, the high-temperature part of the geothermal water drives the absorption heat pump, which further saves steam. By coupling with a 35 MW biomass-fired CHP plant, the system performance of the new integrated system is investigated. According to thermodynamic analysis, the reasons for the increase in power generation are divided into three categories: the transformation of the plant itself, the high-grade steam saved by the ejector, and geothermal assistance. The geothermal-electricity conversion rate of the three coupling schemes is at a high level. After the optimization, the total exergy efficiency of the new system has been greatly improved. The reason is that the absorption heat pump absorbs low-grade geothermal energy, saving some high-grade steam, and the addition of geothermal energy changes the equipment operating conditions reduce exergy loss. Moreover, the economic analysis shows that the new coupled system has significant economic advantages.