High-temperature electrolysis

In a society based mainly on renewable energy, storage and transport of this energy from the point of production to the point of consumption will play an important role. The main reason for this is that wind and solar energy production cannot be turned on and off at will. It is necessary to convert surplus electricity from, e.g., wind power to chemical energy in the form of compounds such as hydrogen, methane or methanol. In this form the energy is easy to store and use in, e.g., vehicles. A fuel cell converts chemical energy to electricity with high efficiency, but it is also possible to reverse the cell process to make it work as an electrolyzer, using electricity and water to make hydrogen and oxygen. As an offspring of our solid oxide fuel cell (SOFC) research we have a project on solid oxide electrolysis cells (SOECs).

The operating temperature of an SOEC is much higher (800-1000 °C) than in conventional electrolysis. For thermodynamic reasons this makes it possible to attain very high efficiencies in the production of hydrogen. Furthermore, the high operating temperature makes it possible to produce methanol and methane by electrolysis of mixtures of CO2 and water. SOEC units will be robust and have a simple structure mechanically.

Such units are not yet on the market. This is due to a high manufacturing price and unsolved problems regarding lifetime and reliability. To solve these problems, we need improved materials and increased knowledge about the optimal process conditions. Our research centers on these questions. Much of the obtained knowledge in this field will also benefit the fuel cell development, and vice versa.

Page updated  24.09.2008

Risø DTU
Fuel Cells and Solid State Chemistry Division
Frederiksborgvej 399
P.O. Box 49
DK-4000 Roskilde
Denmark
Tel: +45 4677 5800
Fax: +45 4677 5858
abf@risoe.dk