Simulation-Based Study of a Novel Integration: Geothermal–Biomass Power Plant

Abstract

This work investigates the potential to integrate a biomass combustor with an existing geothermal power plant. The motivation is to identify the most cost-effective approach to boost the geothermal turbine power output using heat from the biomass combustor to superheat the geothermal steam upstream of the turbine inlet. Different alternative integration configurations were identified and simulated using Aspen Plus software to evaluate their performance in terms of incremental power output and efficiency. Of the three different alternatives proposed, only one of them looked promising—this configuration uses the saturated well-steam for partial preheating of the combustion air. The most promising integration options are compared on the basis of their levelized cost of electricity. The key conclusion is that one should use low-grade heat for low-level heating (well-steam for air preheating) and high-grade heat from the flue gas for steam superheating. Also, the quantity and quality of biomass available dictate the hybrid configuration selected. A proper design of the steam turbine (higher efficiency at higher steam inlet temperatures) is also necessary to enhance the performance of the hybrid geothermal–biomass power plant.