Hydrogen will increase in importance in the future, in order to reduce our dependence on fossil fuels. Hydrogen can be sustainably generated by using solar energy to split water into hydrogen and oxygen. The resulting clean fuel can be stored, used as a fuel in transportation or, when necessary, converted into electricity. However, to produce hydrogen from solar energy requires rare and costly materials – for both the solar cells as well as the catalytic components – to capture energy and convert it.

LRESE

Researchers from the Laboratory of Renewable Energy Science and Engineering (LRESE) are, however, using concentrated sunlight to produce large quantities of hydrogen at a modest cost. To achieve this, they have built an improved electrochemical system that – combined with a solar collector and smart heat management – produces hydrogen from solar energy with an efficiency of 17% and with an unprecedented power and current density. And even more important: the new technology is stable and can cope with the daily sunlight variations.

Water

In this new method, a thin layer of water flows over a solar cell in order to cool it. The system temperature remains relatively low, which means that the solar cell can have a higher efficiency. At the same time, the heat extracted by the water is passed to the catalytic sites, which makes the chemical reaction more efficient and increases the hydrogen production.

The researchers used the unique solar simulator at LRESE to demonstrate the stable performance of their method. The results of these experiments at a laboratory scale showed so much promise that the system has now been scaled up and is being tested outside the laboratory on the campus of the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Lausanne. A parabolic mirror with a diameter of 7 metres has been installed, which concentrates the sunlight by a factor of 1000 and provides the system with energy.

The researchers estimate that the system can be used for more than four years before any components need to be replaced, and some 20 years with replacing only a few parts every four years.

The research has been published in Nature Energy.

Source: EPFL