Toward Large‐Scale Hydrogen Production from Water: What Have We Learned and What Are the Main Research Hurdles to Cross for Commercialization?

Abstract

The focus of this study is evaluating the status of the most promising methods for water splitting to H2 and O2 with their implementation in mind. These are thermochemical water splitting, photocatalytic (PC) and photo‐electrocatalytic (PEC) water splitting, and water electrolysis. In addition to evaluating their coherence, potential, and cost, some misconceptions in the PC H2 production from water over suspended powder catalysts are highlighted. A few needed research directions at the fundamental level together with the main hurdles to cross for large‐scale production are presented and in some cases discussed. Although an increasing level of activity has taken place in the last few years for large‐scale hydrogen production from water, this is still marginal (at the megawatt scale). A considerable investment in different technologies is needed for a noticeable impact on the environment to occur with an objective to decrease the world dependence on fossil fuels (the terrawatt scale).

Seawater electrolysis for hydrogen production: a solution looking for a problem?

“…Today, over 95% of the 70 million tons of hydrogen produced annually comes from steam methane reforming (SMR), releasing 830 million tons of CO2 every year. 2,3 While blue hydrogen routes coupling SMR to carbon capture and storage (CCS) technologies are being tested at scale 4 , green or sustainable hydrogen made from water electrolysis and powered by low-carbon energy is crucial to attain climate neutrality. 2,[5][6][7] As the price of renewable electricity continues to plummet, sustainable hydrogen production via water electrolysis is gaining momentum globally.…”

The Merit and the Context of Hydrogen Production from Water and Its Effect on Global CO2 Emission

“…The power of hydrogen and its important effect on cleaning the environment can be seen when it is used as fuel for transport, heat and other energy applications, as these applications represent over 70% of CO 2 emissions worldwide. This poses a much bigger problem for R&D; hydrogen needs to be made at an unprecedented scale, much larger than the present one, and from water, not from methane [5]. This is a daunting task that is probably not fully appreciated nor given its level of importance.…”

Artificial photosynthesis for high‐value‐added chemicals: Old material, new opportunity

“…Most studies of artificial photosynthesis for value‐added chemicals are currently focused on several fundamentals in terms of energy band structure, activation energy, and product selectivity (Figure 1C). Indeed, more factors remain, such as stability, cost‐effectiveness, or environmental issue, while these issues are much close to commercialization while the current step of research on artificial photosynthesis is still yet to be commercialized 53 . Thus, controlling the three abovementioned factors to increase selectivity would lead to a high R value of the desired value‐added chemical production to achieve future commercialization.…”