Multi-objective optimization design and operation strategy analysis of BCHP system based on life cycle assessment

The promising energetic and environmental benefits of building cooling heating and power (BCHP) system are greatly dependent upon its design and operation strategy. In this paper, the energy and emission flows and different operation strategies of a BCHP system driven by gas engine are analyzed. Life cycle assessment (LCA) is employed to assess and compare the whole life energy saving potentials and pollutant emission reductions of BCHP system with the traditional energy system. Furthermore, energy consumption and three pollutant-related impacts, global warming, acid precipitation and respiratory effects, are selected as objective functions to optimize the gas engine capacity of BCHP system in different operation strategies. A numerical case of BCHP system for a commercial office building in Beijing, China is applied to obtain the optimum BCHP alternative in terms of the comprehensive energy and environment performance. The uncertainty of different evaluation criteria weights is also analyzed to show their influences on the optimal design and operation strategy. The results show that a reasonably sized BCHP system with an electric load-following strategy has the best performance under a wide interval of criteria weights, when the energetic and environmental benefits of producing excess electricity for nearby users are not considered.

► System size and operation mode are optimized to obtain the best integrated performance.
► System operation and fuel acquisition are important to the life cycle assessment result.
► When BCHP system runs following thermal load, the maximum energy saving can be achieved.
► When BCHP system runs following electricity load, the environment benefits are friendly.
► Influences of different evaluation criteria weights on the optimal result is analyzed.