Performance analysis of PEMFC-assisted renewable energy source heat pumps as a novel active system for plus energy buildings

The adoption of plus energy buildings (PEBs) has been considered extensively in various nations for carbon neutralization. However, studies on suitable active systems that can efficiently supply heating, cooling, and electrical energy to PEBs are lacking. This study proposes PEMFC-assisted renewable energy source heat pumps (PEMFC-RSHPs) as active systems for plus energy buildings. In the steady-state simulations using TRNSYS, the waste-heat recovery effect was investigated at various current densities and PEMFC temperatures. In the transient simulations, the seasonal operating characteristics, energy, economic, and environmental performances of PEMFC-RSHPs using air, raw-water, and ground energy sources were analyzed. During the heating season, the maximum primary energy efficiency (PEF) of a PEMFC-assisted ground source heat pump (GSHP) was approximately 0.252 at an optimal current density of 0.8 A cm⁻². However, during the cooling season, the PEMFC-assisted raw-water source heat pump (RWSHP) showed the highest PEF of 0.407 at an optimal current density of 0.7 A cm⁻². In addition, the CO₂ emissions of the PEMFC-GSHP using green hydrogen were 54.3% lower than those using gray hydrogen, although the economic feasibility was still challenging. In conclusion, the PEMFC-GSHP using green hydrogen is the most feasible active system for PEBs.