Thermoeconomic analysis of co-firing combined cooling, heating, and power system based on energy level.

• Auxiliary cost allocation equations are modified based on energy level. • Different cost allocation results between the modified and previous methods are indicated. • Unit exergoeconomic costs of electricity increases 21.10 and 22.90 USD/MWh under summer and winter conditions, respectively. • Sensitivity of the exergoeconomic cost to fuel prices and some non-energy factors is discussed. In this work, exergy and exergoeconomic cost analyses are applied to biomass and natural gas co-firing in a combined cooling, heating, and power (CCHP) system, based on the structural theory of thermoeconomics. The thermoeconomic model for the investigated co-firing CCHP system is defined to quantify the productive relationships among the various components. The unit exergy/exergoeconomic cost of all flows in the productive structure are calculated by solving the characteristic equations and exergy/exergoeconomic cost equations together with the auxiliary cost allocation equations. A comparative analysis between the previous auxiliary cost allocation method and the method based on energy level is presented. Moreover, the production performance of components under summer and winter conditions are evaluated based on the exergy cost analysis. The results show that, compared with the previous method, the exergoeconomic costs of electricity with higher energy level increase 21.10 and 22.90 USD/MWh under summer and winter conditions, respectively, while the costs of other products with lower energy level decrease. Furthermore, a sensitivity analysis is presented to analyze the variation of the unit exergoeconomic cost of products with fuel prices and some non-energy factors. In conclusion, the structural theory of thermoeconomics integrated with auxiliary cost allocation equations based on the energy level can provide reasonable and accurate results for multi-product energy systems. [ABSTRACT FROM AUTHOR]