From green hydrogen to electricity: A review on recent advances, challenges, and opportunities on power-to-hydrogen-to-power systems

The energy sector is responsible for around two-thirds of greenhouse gas emissions, mainly relying on fossil fuels. Thus, the industry must make substantial changes as part of the global energy transition toward a carbon-neutral society. Green hydrogen has the potential to boost the transition to clean and renewable energy while providing stability and reliability to power grids. This work reviews the most recent developments of Power-to-Hydrogen-to-Power (P2H2P) systems: conversion of power to hydrogen, its storage, transport, and re-electrification, with emphasis on their technical characteristics, novel modeling approaches, and implementation challenges. The main opportunities to exploit the potential of P2H2P are associated with cost efficiency and innovation, sector coupling, and reduction of grid dependence. In such a way, P2H2P systems would become cost-competitive while decarbonizing sectors. Furthermore, the gradual maturity of technology and political support would encourage the development of sustainable energies for zero-emission economies.