Conventional biogas-driven distributed energy systems concern the cascaded utilization of thermal energy; however, the chemical energy in the fuel is lost during the combustion process. To solve the problem, this paper designs a solar-and-biogas-fired CCHP integrated with chemically recuperated gas turbine, which is capable to make full use of both chemical and physical energy; also, the issues of high consumption of fossil fuel for biogas digester thermal insulation can be addressed by a novel combination of low concentration ratio of trough solar collectors. By performance comparison, the new design achieves a high net solar-to-electric efficiency of 19.71% which is higher than the optimal power efficiency (~16.00%) of a trough solar thermal power generation system. Besides, the new design can save 116.5 kg/h of natural gas (100%) compared with the conventional one. The new design broadens the possibility of the complementary use of multiple renewable energy sources.
Keywords biogas reforming, distributed energy system, chemically recuperated gas turbine, solar energy, latent heat recovery