Identifying Key Design Criteria for Large-Scale Photocatalytic Hydrogen Generation from Engineering and Economic Perspectives

Photocatalytic hydrogen (H-2) generation has emerged as a promising approach for direct conversion of solar energy into green H-2 fuel. Prior works predominantly focused on photocatalyst material development and optimization with photoreactor and system design receiving considerably less attention. Further, significantly less focus has been devoted to the economic feasibility study of photoreactor systems. Therefore, this Perspective contemplates photoreactor design and scale up from an economic viewpoint. The economics of two popular large-scale photoreactor designs, (i) panel and (ii) slurry based, are evaluated. This Perspective suggests that the design of a photocatalytic slurry system is approximately 12% more cost effective than a panel photoreactor system under the base-case scenario in producing 10 kg H-2 /day. The analysis also suggests that a cost reduction of up to 75% can be achieved if the photon conversion efficiency is increased from 1% to 5%, indicating that research and development should continue to be undertaken to increase process efficiency via photocatalyst and system engineering. In addition, other considerations, such as improving photocatalyst reusability (to give a photocatalyst lifespan of at least 1 year), reducing photocatalyst cost (using non-noblemetal-based photocatalysts) and increasing input photon density (installing a solar concentrator to harness more than 1 Sun intensity), will each impose an additional 20-30% of the cost.

Automated summary

This article discusses and evaluates the design and scale-up of photocatalytic reactors from an economic perspective. It finds that a photocatalytic slurry system is more cost-effective in producing H-2 fuel compared to a panel photoreactor system. It also suggests that increasing photon conversion efficiency and considering factors such as photocatalyst reusability and cost reduction can significantly impact the overall cost.