Is solar hydrogen a viable solution for energetically self-sustainable off-grid buildings?

A micro-cogeneration solution based on an alkaline fuel cell, supplied by solar hydrogen to satisfy electric and thermal energy demands in an off-grid building, is investigated. Hydrogen is produced by using PV surpluses through an alkaline electrolyzer and stored in a pressurized gas tank. Regarding a reference building with a gross footprint of 100 m2 affected by severe winter climate conditions and heated by a radiant floor supplied by an airwater heat pump, TRNSYS simulations showed that 14.4 kWp of PV power and 5 m3 of hydrogen tank volume ensure the building energy self-sustainability. Indoor comfort conditions are achieved by observing air temperatures always in the range of 19-21 °C during winter. The thermal power recovered from the fuel cell reduced DHW demand noticeably. Results show that hydrogen acts as an inter-seasonal storage with summer overproductions needed for the fuel-cell winter operation. An economic analysis confirms that the system is profitable when compared with electric storage made of batteries periodically replaced.