Thermodynamic analysis and economic assessment of an improved geothermal power system integrated with a biomass-fired cogeneration plant

Abstract A novel geothermal power system integrated with a biomass-fired cogeneration plant has been developed, which feeds the obtained geothermal energy into the steam cycle of the biomass plant. Under the cogeneration scenario, the geothermal water provides heat to the supply-water for district heating together with the extraction steam of the turbine, while in the power generation scenario, the geothermal water is employed to warm the feedwater of the biomass plant. Consequently, much extraction steam of the turbine can be saved to produce additional electricity that can be regarded as geothermal energy-based electricity. Based on a 35 MW biomass cogeneration plant, the thermodynamic and economic performance of the proposed system was evaluated, and the effects of the main parameters were investigated as well. The results indicated that the geothermal power generation efficiency can reach 25.47% or 5.62% under the cogeneration mode or power generation mode. In a whole year, 16935.48 MWh electricity can be yielded from geothermal energy with an annual geothermal power generation efficiency of 17.08%. The levelized cost of geothermal energy-based electricity is only 0.0329 $/kWh when adopting the new design. Generally, the novel concept is quite advantageous from both the thermodynamic and economic perspectives.