Multi-generation system incorporated with PEM electrolyzer and dual ORC based on biomass gasification waste heat recovery: Exergetic, economic and environmental impact optimizations

In this paper, a multi-generation system comprising a dual organic Rankine cycle equipped with an ejector refrigeration loop, a biomass gasification process and a proton exchange membrane electrolyzer is developed to produce the syngas, power, refrigeration effect, heating load, hydrogen and oxygen. R245fa-R134a, R236fa-R1234yf and R600-R290 are applied as three organic working fluid groups inside the dual organic Rankine cycle. The system concerned is modeled using the exergy, exergoeconomic and exergoenvironmental analyses. An elitist non-dominated sorting genetic algorithm is individually used to optimize the thermodynamic, economic and environmental performances of the system for each working fluid group. The LINMAP and TOPSIS decision makers are applied to select the optimum performances of the system and electrolyzer. The optimization results show that the hydrogen cost and environmental impact per unit exergy are improved within 49.18% and 34.58%, respectively through the LINMAP method for R236fa-R1234yf. In addition, the maximum improvement in the total cost rate of the system is calculated within 39.5% for R245fa-R134a through the TOPSIS procedure and the highest increment in the environmental impact rate belongs to R236fa-R1234yf by about 34.69% using the LINMAP decision maker.