A probability constrained multi-objective optimization model for CCHP system operation decision support

Novel performance curves to determine optimal operation of CCHP systems

Combined cooling, heating, and power (CCHP) systems use waste heat from on-site electricity generation to meet the thermal demand of the facility, which includes cooling, heating, and hot water. When compared with traditional set-ups of grid-generated electricity and an on-site boiler for heat, CCHP systems are capable of improving fuel utilization and lowering emissions. One of the critical components affecting the performance of CCHP systems is the prime mover. The objective of this investigation is to study the effect of the prime mover size and operational strategy on the energy, economical, and environmental performance of CCHP systems under different pricing structures. Three different sizes for the prime mover, a natural gas engine, are simulated under different operational strategies such as: following the electric demand of the facility, following the thermal demand of the facility, and following a constant load. The results obtained for the CCHP system will be compared with a reference building operating under conventional technologies to determine the advantages or disadvantages of the CCHP system's operation. In addition, a simple optimization of the system's operation determines the best engine load for each hour during the simulation that minimizes cost, primary energy consumption (PEC), or carbon dioxide emissions (CDEs). For this study, three locations in different climate zones that have different electricity rate structures were chosen: one with a constant flat rate; one that uses seasonal rates; and one that incorporates block charges. Historical monthly natural gas rates were also used. Since most authors perform cost analyses using a fixed constant rate for both electricity and natural gas, a comparison is made between the cost results from using the actual cost data to those that use an average fixed rate. In general, among the three engine sizes that were simulated, the smallest engine yielded the lowest costs and lowest PEC; but, no such trend was found with regard to the CDE. The results also showed that the performance of the evaluated CCHP system can be improved by optimizing the system based on cost or primary energy.

Multi-objective optimization of district energy systems with demand response

Multi-objective operation optimization and evaluation of large-scale NG distributed energy system driven by gas-steam combined cycle in China

Performance analysis and optimization of a combined cooling, heating and power system based on active regulation of thermal energy storage

A MOEA/D approach using two crossover strategies for the optimal dispatches of the combined cooling, heating, and power systems

In order to overcome the limitation of traditional single-objective optimal operation method for the multiple energy flows system combined cooling, heat and power (CCHP), this paper presents a multi-objective comprehensive optimization model for CCHP with renewable energy resources and energy storage devices based on the fuzzy theory and PSO. The model utilizes the membership function to fuzzify each objective function. Then linearly weighted sums the objective functions with coefficient of variation method and solve the model by PSO algorithm. The simulation results based on the case of a real district show that compared with traditional optimization method, the comprehensive optimization model established in this paper can take each important performance index into account and effectively optimize the dispatch of energy resources of the CCHP system with renewable energy.

• Methodology for exergy analysis of bio-solar CCHP/HP systems. • Transient and dynamic model for optimal sizing of gasifier and other components. • Optimal sizing can significantly reduce irreversibility losses. • Biomass types have marginal effect on system exergy efficiency. Biomass-based, small-scale Combined Cooling, Heating and Power (CCHP) systems can increase the energy autonomy of building complexes while reducing their Greenhouse Gases (GHG) emissions. In combination with air-to-water Heat Pumps (HP), highly efficient energy systems can be designed, which allow for high flexibility in serving thermal and electric demands. This study presents an exergy evaluation of such a small-scale CCHP/HP system using a dynamic modelling approach based on gasification of various types of woody biomass. The transient model takes into account the effects of the biomass chemical composition as well as of ambient temperatures on the exergy performance of all key components for various CCHP system sizes supporting an HP system. The model has been applied in a case study for a historic building complex, where the CCHP sub-system would support an HP-subsystem allowing for downsizing the latter. The results show that smaller CCHP systems operate with higher exergy efficiency, because for larger systems the heat transfer from the engine and the operation of the absorption chiller are less exergy efficient. The electric load-following CCHP subsystem reaches exergy efficiencies of up to 13.3%, indicating huge improvement potential for system and sub-system design. It was also found that the biomass composition heavily influences the exergy efficiency of the gasifier and in turn changes the exergy efficiency of the syngas engine and the entire CCHP sub-system.

Energy flow optimization method for multi-energy system oriented to combined cooling, heating and power

Micro-combined cooling, heating and power systems hybrid electric-thermal load following operation

Novel flexibility evaluation of hybrid combined cooling, heating and power system with an improved operation strategy

Integrated energy systems with CCHP and hydrogen supply: A new outlet for curtailed wind power

Poor economic performance has limited the diffusion of the combined cooling, heating, and power (CCHP) system. Various factors influence the economic performance of the CCHP system. To analyze the impacts of these different factors and promote the CCHP system, this study evaluated its comprehensive performance through a multi-criteria method, using an amusement park resort in Shanghai as a research case. First, three CCHP systems with different penetration rates were presented and simulated in a transient simulation model for comparison. The economic and environmental performance of these different penetration CCHP systems were evaluated based on the dynamic payback period and carbon dioxide emissions. The impacts of investment cost, energy prices, investment subsidy and a carbon tax on the economic performance of the three systems were discussed, and a sensitivity analysis was used to compare these factors. The results show that the current subsidy can reduce the economic gap between the CCHP system and the conventional system, but it still needs to be increased by 1.71 times to achieve market competitiveness of the CCHP system with 100% penetration under the current investment cost and energy prices. In addition, the introduction of a carbon tax could accelerate the promotion of the CCHP system. When the carbon tax reaches 25 $/ton, the CCHP system becomes the best choice of energy supply system.

Risk-involved dominant optimization of multi-energy CCHP-P2G-based microgrids integrated with a variety of storage technologies

Multi-objective optimal dispatching of combined cooling, heating and power using hybrid gravitational search algorithm and random forest regression: Towards the microgrid orientation