Building a green hydrogen future: policy approaches for photocatalytic water splitting

Published on December 3rd, 2024

The energy transition plays a crucial role in reducing greenhouse gas emissions (GHGs), mainly by global economies shifting to renewable energy (i.e., wind, solar, biomass, hydropower), investing into smart grids and carbon capture and storage (CCS), as well as electrifying transport, heating and cooling systems. Green hydrogen, too, is considered a major factor in the transition away from fossil fuels. It would act as a clean energy source, powering planes, ships and trucks; it would heat homes, store excess renewable energy supply, balancing electricity grids, whilst help decarbonize hard-to-abate industry sectors, including steel and cement (1). Recently, the world's two largest economies have advanced new hydrogen policies, including the EU's “Important Projects of Common European Interest'” (IPCEI) initiatives, the EU Hydrogen Bank, and the US Inflation Reduction Act.

Photocatalytic water splitting is the emerging technology that offers a promising solution for generating renewable, or green, hydrogen by converting solar energy into chemical energy. By using sunlight to split water, photocatalytic systems produce hydrogen without emitting greenhouse gases, offering a pathway to a carbon-neutral energy system. However, the transition from laboratory-scale demonstrations to large-scale implementation faces several technical, political, and economic challenges (2). Building on this foundation, this policy outlook explores large-scale hydrogen production, focusing on the Frontiers in Science lead article “Photocatalytic water splitting for large-scale solar-to-chemical energy conversion and storage” by Hisatomi et al. (3). The ultimate aim from a policy perspective is to align this emerging technology with global climate goals and to provide a roadmap for integrating photocatalytic hydrogen production into existing energy systems.

Challenges in scaling-up photocatalytic water splitting for hydrogen production

The policy implications of green hydrogen relate in part to the technological challenges involved. A major barrier to the widespread adoption of photocatalytic water splitting is the need for efficient photocatalysts capable of high solar-to-hydrogen (STH) conversion rates (3). Current research is focused on improving the performance of particulate semiconductors, which are critical for water splitting with high energy efficiency. However, achieving this on a commercially viable scale remains a challenge.

Scaling up photocatalytic water splitting requires more than just improving efficiency. Large-scale implementation will require the development of reactors covering areas as large as 1 km² to produce significant amounts of hydrogen. This scaling presents logistical challenges, such as the development of materials for reactors, piping, and safety systems. Current research has demonstrated near-perfect efficiency under controlled conditions using ultraviolet (UV) light. However, practical application will require robust designs capable of operating in a wide range of environmental conditions.

One of the policy challenges hindering the large-scale implementation of photocatalytic hydrogen production is the lack of a consistent international regulatory framework. Although progress has been made, such as the work of the International Organization for Standardization (ISO) Technical Committee 197 on hydrogen technologies (4), there are still no comprehensive standards governing the production, storage, and transport of hydrogen.

The lack of a well-established green hydrogen value chain is another major barrier. To achieve large-scale deployment, new value chains must be developed to integrate hydrogen production, distribution, and consumption.

Policy recommendations

Support for research and development

To accelerate the adoption of photocatalytic water splitting, targeted investment in research and development is crucial. Governments and international organizations should allocate funds to support interdisciplinary research efforts aimed at improving photocatalyst efficiency and scalability. Public-private partnerships will play a key role in fostering innovation, enabling rapid commercialization of next-generation photocatalytic systems. These partnerships facilitate faster development of highly efficient photocatalytic systems by enabling private firms to access both funding and research expertise, reducing time-to-market for photocatalytic technologies. By bridging research and commercialization, public-private collaborations can streamline scaling efforts, reduce costs, and position new photocatalytic systems for widespread, practical application.

Public funding should also be directed towards large-scale pilot projects that demonstrate the feasibility of photocatalytic water splitting. Such projects will provide critical insights into the operational costs, long-term performance, and safety of large-scale hydrogen production. These demonstrations should be conducted in regions with high solar irradiance and adequate temperatures to maximize efficiency and potential hydrogen output.

Regulatory frameworks for hydrogen safety

One of the major risks associated with photocatalytic water splitting is the handling of oxyhydrogen gas, which can be highly explosive. Establishing stringent safety standards for reactor design, gas separation, and hydrogen recovery is essential. International safety standards should be developed to guide the safe implementation of this technology at scale, drawing on best practices from other industries, such as chemical and nuclear energy.

Establishing a global regulatory framework will also be crucial for promoting fair competition and ensure that hydrogen produced via photocatalysis meets safety and environmental standards. Countries must work together to create standardized (e.g., ISO) regulations that support the development of hydrogen as a global energy commodity.

Infrastructure for hydrogen storage and transportation

Significant investment in hydrogen infrastructure is required to enable photocatalytic hydrogen production to be integrated into national energy grids. This includes the development of pipelines, storage facilities, and hydrogen refueling stations. The newly developed units should be approved by chemical engineering specialists to ensure compliance with safety requirements. Governments should incentivize the construction of this infrastructure through tax breaks, grants, and public-private partnerships. Additionally, fostering international coordination, in areas such as regulation, trade and market access, infrastructure development, and technology and research development, will be crucial to facilitate the smooth operation of hydrogen markets across borders.

Creating a market for green hydrogen

Policymakers must also create market demand for green hydrogen by integrating it into national energy strategies. This can be achieved through industry incentives such as carbon credits, renewable fuel standards, and long-term purchase agreements, which will stimulate demand for hydrogen as an alternative to fossil fuels. Additionally, international government cooperation is needed to establish hydrogen trade networks, enabling countries with abundant solar resources to export green hydrogen to regions with high demand.

In Mexico, for example, the focus is still on developing the production capacity, regional supply chains, and promoting consumer adoption of hydrogen products as part of the transition away from fossil fuels. However, there is currently no national strategy for developing a green hydrogen industry and the country has yet to adapt its existing energy infrastructure to it. Thus, including green hydrogen formally in Mexico's legal framework and establishing regulatory standards for the industry could significantly advance market growth. This approach could also serve as a model for other countries looking to transition to renewable energy sources.

Conclusions

Photocatalytic water splitting represents a breakthrough technology in the quest for sustainable energy solutions. However, to achieve large-scale implementation, a coordinated effort between governments, industries, and institutions is urgently needed. To overcome the technical, economic, and political challenges outlined here, policymakers must prioritize investment in research and infrastructure, establish regulatory frameworks, and create markets for green hydrogen.

By aligning photocatalytic water splitting with global climate goals, we can unlock its potential to provide a clean, renewable fuel source that will drive the energy transition and help establish a sustainable future.

1. Altaf CT, Demir O, Colak TO, Karagöz E, Kurt M, Sankir ND, et al. Decarbonizing the industry with green hydrogen. In: Sankir M, Sankir ND, editors. Towards green hydrogen generation.  Hoboken, NJ: John Wiley and Sons, Scrivener Publishing (2024). 1–48. doi: 10.1002/9781394234110.ch1 

2. Ji M, Wang J. Review and comparison of various hydrogen production methods based on costs and life cycle impact assessment indicators. Int J Hydrog Energy (2021) 46(78):38612–35. doi: 10.1016/j.ijhydene.2021.09.142 

3. Hisatomi T, Wang Q, Zhang F, Ardo S, Reisner E, Nishiyama H, et al. Photocatalytic water splitting for large-scale solar-to-chemical energy conversion and storage. Front Sci (2024) 2:1411644. doi: 10.3389/fsci.2024.1411644 

4. International Organization for Standardization. ISO/TC 197 Hydrogen technologies [online]. Available at: https://www.iso.org/committee/54560.html 

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