Reliability, economic, and environmental analysis of fuel-cell-based hybrid renewable energy networks for residential communities

A fuel cell system has received considerable interest as an effective combined heat and power (CHP) generation system. In particular, a polymer electrolyte membrane fuel cell (PEMFC) has been regarded as suitable for residential buildings as their low-temperature heat generation can be used to meet high heat demand. This study aims to optimize renewable energy networks on the basis of PEMFC, considering both different system mixes in an energy network and different system sizes. This study scrutinizes the overall performance of different hybrid energy networks based on PEMFC in terms of the reliability, economic, and environmental perspectives when both the heat and power generation from PEMFC are used to meet the energy need of residential communities. A hybrid renewable energy network for a residential community with 12 households is modeled and simulated using TRNSYS to evaluate the performance of different hybrid energy network scenarios. Four scenarios are created on the basis of the base case with a gas-based fuel cell (FC) system and heat tank by incrementally adding renewable energy systems-a ground source heat pump (GSHP) system, photovoltaic (PV) system, battery, electrolyzer, and hydrogen storage tank. First, the impacts of individual design variables are quantified using variance-based sensitivity analysis for identification of key design variables. Second, the cost optimization of hybrid energy network is performed under the four scenarios of system mixes. Last, the effects of the key design variables for each scenario are further scrutinized through heat maps. The analysis results of the case study confirms the feasibility of a FC system as part of renewable energy network for residential buildings. Furthermore, Scenario 3 comprising a FC system, GSHP, PV system, and battery is found to be the optimal design in terms of all the three aspects. This result suggests that the whole performance of hybrid energy network can be improved when other renewable systems are included in the network to complement the FC system. In contrast, Scenario 4 using green hydrogen has poorer performance than Scenario 3 using gas as fuel due to high unit prices of hydrogen systems and low efficiency of green hydrogen production. Furthermore, external factors such as utility prices and system unit prices are considered in further analysis and found to have great influence on the optimal design of energy networks.