Thermo-ecological assessment of CCHP (combined cold-heat-and-power) plant supported with renewable energy

The current energy policy requires a constant technology development towards more sustainable energy transformation systems. Cogeneration and the use of renewables are two important solutions available to achieve this goal. If cogeneration is applied locally, e.g. as CHP (combined heat-and-power generation) modules with internal combustion engines, it leads to additional advantageous effects due to the decrease of energy transmission losses. To analyse such systems from the point of view of resource efficiency, the pure energy analysis is not sufficient since the quality of particular energy carriers is not evaluated.The paper presents the exergo-ecological analysis using the concept of TEC (thermo-ecological cost) for a selected CCHP (combined cold-heat-and-power) trigenaration system consuming both renewable and non-renewable resources. The analysed CCHP system is equipped with a photovoltaic plant, an internal combustion engine fired with biogas and an adsorption chiller. The peak demand for electricity is covered from the grid, and the peak demand for heat is covered by a gas boiler. The seasonal availability of renewable sources (solar radiation and biogas) is taken into account.It has been demonstrated that the obtained TEC depends on the type of generated carrier (electricity/heat/cold), on internal process irreversibility and the emitted pollutants, and on the type of primary energy supplied to the analysed systems. The values of TEC range between 0.22 for electricity generated in the photovoltaic plant and 4.72 for the cooling agent generated in the adsorption chiller.