Abstract
A strategic roadmap for non-carbonized fuels is a global priority, and the reduction of CO2 emissions
is a key focus of the Paris Agreement to mitigate the effects of rising temperatures. In this context,
hydrogen (H2) is a promising non-carbonized fuel, but the pace of its implementation will depend on
the engineering advancements made at each step of its value chain. To accelerate its adoption, various
applications of hydrogen across industries, transport, power, and building sectors have been identified,
where it can be used as a feedstock, fuel, or energy carrier and storage. However, widespread usage of
hydrogen will depend on its political, industrial, and social acceptance. It is essential to carefully assess
the hydrogen value chain and compare it with existing solar technologies. The major challenge to
widespread adoption of hydrogen is its cost as outlined in the roadmap for hydrogen. It needs to be
produced at the levelized cost of hydrogen (LCOH) of less than $2/kg to be competitive with the
established process of steam methane reforming. Therefore, this review provides a comprehensive
analysis of each step of the hydrogen value chain, outlining both the current challenges and recent
advances.