Green Hydrogen: Compact Power Plants

In a groundbreaking joint research effort known as the Neo-PEC project, three Fraunhofer institutes have joined forces to create a cutting-edge modular solution that allows for highly flexible hydrogen generation and supply using solar energy.

The focal point of this innovative development is a tandem PEC module, which bears resemblance to traditional photovoltaic modules but with a key distinction: the electricity generated is not intended for later electrolysis in a separate process. Instead, the entire hydrogen generation process occurs within the same unit, emphasizing the importance of maintaining a strict separation between hydrogen and oxygen throughout the process.

To construct the tandem cell, experts coat standard float or plate glass with semiconducting materials on both sides. When sunlight reaches the glass, one side of the module absorbs short-wavelength light while the long-wavelength light passes through the upper layer and is absorbed on the reverse side. Hydrogen is released on the cathode side, while oxygen is produced on the anode side.

Over the course of the three-year project, Fraunhofer scientists focused on researching and developing high-purity semiconductor materials, utilizing gentle coating methods to enhance the hydrogen yield. Dr. Arno Görne, group manager at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS, highlights the impact of the vapor phase deposition process on reactor activity and material properties.

The resulting reactor boasts an active surface area of half a square meter, efficiently generating hydrogen that can be captured and quantified directly. A single module exposed to European sunlight conditions can produce over 30 kilograms of hydrogen per year per 100 square meters, enabling significant potential for applications such as hydrogen-powered vehicles.

Collaboration across Fraunhofer institutes was key to the project's success, with each institute contributing unique expertise. Fraunhofer IKTS focused on materials and processing for the photoactive layer, while the Fraunhofer Institute for Surface Engineering and Thin Films IST brought their experience in physical vapor deposition. The Fraunhofer Center for Silicon Photovoltaics CSP handled reactor design, production, and module evaluation.

Following the project's conclusion, the Fraunhofer teams showcased their reactor at the Achema 2024 trade show in Frankfurt, marking the beginning of future plans. They aim to continue their collaborative efforts in a new project and further enhance their solution in partnership with the private sector, paving the way for efficient decentralized hydrogen generation and supply.