Design optimization for an integrated tri-generation of heat, electricity, and hydrogen powered by biomass in cold climates

•Economic viability and environmental effects of a biomass-powered tri-generation system.•Developing a methodology for incorporating reliability, availability, and maintainability (RAM) analysis with optimization techniques.•A flexible modular design strategy adjustable to various types of energy inputs for hydrogen, heat, and electricity generation.•Incorporation of other operational criteria such as mean time for logistics, mean time to preventive maintenance.•Establishment of a platform for extending the integrated RAMS optimization approach to other phases of the project other than design. For green hydrogen energy systems driven by renewables, despite the complexities in design and operations, uncertainties related to availability of infrastructures or seasonality of resources are significant as well as the uncertainties in technical side such as adoption of technologies for energy generation, conversion, and storage. Such uncertainties put the economy and sustainability of these systems under shadows. Consequently, it has been attempted to balance and offset the impacts of uncertainties by means of providing the side products such as hydrogen. An enviro-economic optimization considering reliability, availability, and maintenance of a biomass-gasification-driven combined heating, hydrogen, and electricity system is considered in this study. The emission penalty cost as well as the electricity and hydrogen generation revenues are also pinpointed as part of the objective function which is the total cost. Such costs incorporate capital cost for purchase and installation of all modules, primary fuel (High Heat Value Woods) purchase, and transportation costs. Probabilistic approach using Weibull function is used for modeling reliability for the whole system. The most optimal values for total cost, hydrogen and electrical modules incomes, rated capacities, utilization times, reliability and maintainability indicators such as mean time to failure and maintenance intervals for modules are derived and compared. The sensitivity to performance parameters and sizing characteristics of those three modules are also investigated. The results support this notion that if there are opportunities to sell hydrogen, it is advantageous to integrate hydrogen module to the heating and power co-generation. The results show that minimum cost is obtained by devoting less rated capacities and utilization times to electricity modules in favor of increasing the hydrogen module uti