Optimization and integration of hybrid renewable energy hydrogen fuel cell energy systems – A critical review

Electricity generation presents the biggest opportunity to lower CO2 emissions and it is foreseen that hydrogen energy technology will play an important role in realising the scenario to cap global warming at 2 °C through replacement of fossil fuels with renewables. The transition to electric power for transport in battery- and fuel-cell-electric vehicles will further increase the need for low-carbon electricity generation. For a successful transition to a renewable energy economy the traditional approach of designing energy systems to meet only goals related to the technology (capacity, availability, reliability) and economics (return on investment, cost to the consumer) must evolve to take on a more holistic viewpoint and be able to take into account other goals addressing environmental and social considerations. This paper reviews approaches for integrating hydrogen energy technology into hybrid energy systems, emphasising electricity generation using a hydrogen fuel cell. Integration of energy storage, sizing methodologies, energy flow management and their associated optimization algorithms and software implementation are addressed. Few published case studies go beyond technical considerations. This reality is discussed in the light of available software packages. A four-dimensional multi-objective meta-heuristic function is proposed with weighting of technical, economic, environmental and socio-political factors to suit the design goals for the energy system.