Energy, economy, and environment optimization of biomass gasification hybrid energy systems integrated with solar and geothermal energies

In the context of dual-carbon, building an efficient, clean, and low-carbon integrated energy system (IES) is a crucial way to realize "carbon peaking and carbon neutrality". This study optimized two biomass gasification combined cooling, heating and power (BGCCHP) systems for energy, environment and economy. Firstly, a basic framework of IES covering a variety of energy conversion devices and energy storage devices is established. Then, a multi-objective operation optimization model of the integrated energy system is built by combining the operation constraints of the system devices. Four kinds of biomass raw materials (rice straw (RS), wheat straw (WS), wood pellet (WP), and corn straw (CS)) and three operating strategies (following thermal load (FTL), following electric load (FEL), and following hybrid electric-thermal load (FHL)) are used in the optimization model. Furthermore, a novel multi-objective artificial gorilla troops optimizer (MOGTO) algorithm is proposed, which obtains the Pareto front by solving the model. Then, the technique for order preference by similarity to ideal solution (TOPSIS) method is used to decide on each optimal solution. The optimization results indicate that BGCCHP-ground source heat pump-solar energy (BGCCHP-GSHP-SE) and BGCCHP-ground source heat pump (BGCCHP-GSHP) systems for all biomass materials and operating strategies outperform separated generation systems. For both BGCCHP-GSHP-SE and BGCCHP-GSHP systems, the CS material allows for the best performance, regardless of the operating strategy, compared to WP, WS, and RS materials. In particular, the combination of CS and FEL results in optimal overall performance for the two BGCCHP systems. The annual cost savings (ACSR), primary energy savings (PESR), and carbon dioxide reduction rate (CDRR) of the BGCCHP-GSHP-SE system reached 30.26 %, 91.66 %, and 94.28 %, respectively. The annual ACSR, PESR, and CDRR of the BGCCHP-GSHP system reached 36.33 %, 88.15 %, and 92.18 %, respectively. Furthermore, integrating solar energy makes the system less economical, while energy and environmental performance significantly improve. In addition, it reduces the installed capacity of the power generation unit (PGU) while the installed capacity of the thermal energy storage (TES) is significantly increased. The sensitivity analysis indicates that higher CS prices potentially worsen the Pareto solution set performance, making the economics of the compromise solution worse, while energy and environmental performance show uncertainty.