Updates on Hydrogen Value Chain: A Strategic Roadmap

Abstract

A strategic roadmap for noncarbonized fuels is a global priority, and the reduction of carbon dioxide emissions is a key focus of the Paris Agreement to mitigate the effects of rising temperatures. In this context, hydrogen is a promising noncarbonized 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 of less than $2 kg^-1 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.

Keywords: consumption; hydrogen; production; storage; transport; value chain.

Figure 1

Scheme outlining the hydrogen value chain fields, interconnection, and roles. Reproduced with permission.^{[ 4 ]} Copyright 2023, TÜV SÜD.

Figure 2

AM0^{[ 27 ]} and AM1.5^{[ 28 ]} solar spectra, together with the portion of the spectrum accessible by a double junction tandem perovskite/Si solar cell. In this example, the hybrid organic/inorganic perovskite is the wide‐bandgap top absorber, with a bandgap of 1.68 eV^{[ 23 ]} (cutoff at ≈740 nm). Single crystalline, n‐type silicon is the narrow‐bandgap bottom absorber, with a bandgap of 1.12 eV at room temperature ^{[ 23 ]} (cutoff at around 1107 nm). AM: Air Mass; UV: Ultraviolet radiation; VIS: Visible radiation; NIR: Near‐infrared radiation; SWIR: short wavelength infrared radiation.

Figure 3

Schemes of a) alkaline water electrolyzer (AWE), b) proton exchange membrane water electrolyzer (PEMWE) and c) solid oxide electrolysis cell (SOEC). Reproduced with permission.^{[ 95 ]} Copyright 2022, SciOpen.

Figure 4

Global electrolysis capacity (MW year⁻¹) becoming operational annually, 2014–2023, historical and announced. Dark blue stands for total and light blue stands for largest project. Reproduced with permission.^{[ 33 ]} Copyright 2022, IEA.

Figure 5

Schematic energy diagram of an H‐type photoelectrochemical cell equipped with a single‐junction semiconducting photoanode absorbing green light (≈495 nm, 2.5 eV) immersed in seawater, under nonequilibrium conditions. Note that the energy axes are not on scale (CB: conduction band; CBm: conduction band minimum; VB: valence band; VBM: valence band maximum; E _F: Fermi level; E _F,n: Quasi Fermi level for electrons; E _F,p: Quasi Fermi level for holes; U: applied potential).

Figure 6

A) Theoretical reaction kinetics controlled by the Butler–Volmer law for water splitting and the electrolysis involving biomass oxidation. For both cases the operating voltages have been determined for a current density of 1 A cm⁻². Adapted from C. Lamy, C. Coutanceau, S. Baranton, Production of Clean Hydrogen by Electrochemical Reforming of Oxygenated Organic Compounds, Academic Press, Cambridge, Massachusetts 2020.^[62] B) Photovoltage as a function of bandgap for selected semiconductors. The Shockley–Queisser (SQ) limit is also indicated. Adapted from Matthew T. Mayer, Photovoltage at semiconductor–electrolyte junctions, Curr. Opin. Electrochem., 2017, 2, 104–110 (themed issue on Solar Cells edited by Michael Grätzel). HER: Hydrogen Evolution Reaction; OER: Oxygen Evolution Reaction.

Figure 7

Salt structures localized along Europe. Reproduced with permission.^{[ 75 ]} Copyright 2020, Elsevier.