Source: Energy & Management Powernews, February 03, 2022
Researchers at the Universities of Ulm and Jena have developed a process with which green hydrogen can be produced "on demand" at any time of day or year.
Green hydrogen produced from renewable energy sources is an integral part of the German government's National Hydrogen Strategy. How it can be reliably produced in the evening and also in winter, when there is little or no sunshine, is being investigated by scientists from the universities of Ulm and Jena in the joint project "CataLight."
The research partners are working on new materials for energy conversion. Photosynthesis from nature serves them as a model here. With a molecular photochemical system, they have now succeeded for the first time in decoupling sunlight-driven hydrogen production from the course of the day. The new system even makes light energy storage possible, so that hydrogen production can start on demand and even in the dark. The researchers published their system in the journal Nature Chemistry.
Previous models for producing hydrogen from solar energy have been inefficient, the researchers write. They have mostly relied on coupling multiple components - photovoltaic cells, batteries and electrolyzers. At each step of the energy conversion process - from sunlight capture to storage to hydrogen production - the energy losses would have added up. This is no longer the case in the system now presented.
Spatial and temporal separation of the substeps
The Ulm alternative is reportedly based on a single molecule that can absorb sunlight, store energy and produce hydrogen. In this compact unit, the spatial and temporal separation of these steps becomes possible. Carsten Streb, professor at the Institute of Inorganic Chemistry I at the University of Ulm, explains, "Light irradiation leads to charge separation and electron storage in our molecule - the result is a liquid fuel that can be easily stored." To produce hydrogen from it, he adds, a proton source is added.
The researchers have tested the performance of their system using a wide variety of analytical methods. They found that the molecular unit exhibited "excellent chemical and photochemical stability."
In the future, the chemists plan to scale up the model. It will serve as a blueprint for decentralized energy storage systems. The scientists see possible applications in climate-friendly electricity and heat generation as well as mobile, solar-powered hydrogen filling stations for trucks and buses.
Author: Davina Spohn