Thermodynamic and economic analyses of a solar-aided biomass-fired combined heat and power system

Abstract

A hybrid renewable energy system for combined heat and power production has been developed and evaluated. The integration is achieved by feeding the heat harvested from sunlight by parabolic trough collectors into the steam cycle of a biomass-fired cogeneration plant. Under the cogeneration mode or power generation mode, the obtained solar heat is exploited to drive the absorption heat pump for providing heat or warm the feedwater into the boiler, saving the extraction steam and contributing to additional power output. The thermodynamic and economic performance of the hybrid system was assessed based on a typical biomass-fired cogeneration plant. The performance of the new design under different operation modes and various solar conditions was also explored. The results indicated that the solar-to-electricity conversion efficiency can reach 19.38% or 16.92% at the design points under different operation modes (cogeneration or power generation); while the biomass consumption and thermal efficiency of the biomass plant are fixed, the cogeneration mode is superior to the power generation mode. Throughout the year, the solar based electricity of 2803.04 MWh can be generated with an annual solar-to-electricity conversion efficiency of 16.16%. Besides, the levelized cost of solar aided electricity is only 0.1306 $/kWh.