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New Paper – Is Photocatalysis the Next Technology to Produce Green Hydrogen to Enable the Net Zero Emissions Goal?

green hydrogen Photocatalysis

New paper – is photocatalysis the next technology to produce green hydrogen to enable the net zero emissions goal?

This perspective paper discusses the development of renewable technologies for green hydrogen production, which is important for energy security and meeting the goals of the Paris Agreement.

Renewable energy, particularly solar energy, is a promising alternative because it has an effectively unlimited supply and can be used to produce solar clean fuels through the selective capture of photons with different energies. However, challenges exist in capturing solar photons due to factors such as the day-night cycle, seasonal changes, clouds, and geographical variations.

Photocatalysis, a simple heterogeneous surface catalytic reaction inspired by natural photosynthesis, has potential for scaling up processes for widespread use. Water splitting through photocatalysis means requires only light, a catalyst, and water, and hydrogen has several advantages as an energy vector, including a high energy content per unit mass, versatility in storage and use, and the potential for cost-effectiveness through the use of hydrogen fuel cells for mobility as well as new burner designs for the industry and the built environment.

The main advantage of photocatalysis over conventional water electrolysis is that there is no need for the (intermediate) generation of renewable energy: sunlight is directly used in a catalyst to split water in hydrogen and oxygen. This represents advantages in particular to countries and regions that have an additionality requirement i.e., because photocatalysis does not require (unlike for conventional water electrolysis) that additional renewable electricity generation is installed to be able to classify the produced hydrogen as low-carbon (i.e., green). As such, photocatalysis has the potential of having a low CAPEX (since no additional renewable energy sources need to be installed) as well as a low OPEX (since no electricity is needed for the generation of hydrogen).  Another advantage of photocatalysis is that it doesn’t require expensive catalyst materials (unlike PEM electrolysis), making it suitable for the current and expected constraints in the availability of materials for hydrogen production.

Photocatalysis is a technology currently being developed and tested in small- and medium-scale pilot projects i.e., its current TRL is 5-6. In the perspectives paper, the authors point at the current challenges to producing large amounts of hydrogen via photocatalysis including improving reactor efficiency, developing multifunctional, efficient solar-driven catalysts, and testing pilot devices. Furthermore, the authors introduce three pilot projects and further efforts from Japan, Spain, and France to illustrate efforts at the laboratory, pilot-device and large-scale levels. In order for solar-assisted photocatalysis to mature as a solution for hydrogen production, these challenges must be addressed to advance the technology readiness level, assess capital expenditure, and enter the market as a cost-effective alternative to conventional water electrolysis.

Link to the article: https://onlinelibrary.wiley.com/doi/10.1002/gch2.202200165

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