A comprehensive literature review on the challenges associated with underground hydrogen storage

The current rate of global warming is greatly increasing greenhouse gas emissions which is only set to worsen the planet's environmental condition. In ensuring a sustainable future, it has become necessary to move away from fossil fuels and adopt renewable energy sources as the primary source of energy generation. Dependency of renewable energy sources on the environment, however, has entailed storing the excess generated energy in bulk for times of need. Hydrogen storage in subsurface porous media has contended to be the buffer for energy storage. Still in infancy, there is little known about the consequences associated with storing hydrogen in naturally existing (depleted oil and gas reservoirs, and saline aquifers) as well as artificially intervened (salt caverns) subsurface geological media. This review article aims to define, characterize, and summarize the different types of subsurface geological media currently considered viable for underground hydrogen storage. Present in this article is also an elaboration of hydrogen's physiochemical properties and the resulting potential interactions that may occur, prospects that need to be addressed and challenges that need to be overcome in ensuring hydrogen's large scale geological storage.