World record Fuel cell works perfectly for 11 years
Scientists at the Jülich Research Centre recorded more than 100,000 hours of operating time for their new variant of a high-temperature fuel cell.
Forschungszentrum Jülich has operated a fuel cell at a temperature of 700 °C for more than eleven years. The more than 100,000 hours service life of the high-temperature fuel cell represents a new record: No fuel cell has supplied electricity for the same time. Proving such a long service life is regarded as an important step in the development of high-temperature fuel cells that achieve the highest levels of efficiency.
Professor Ludger Blum of the Jülich Institute for Energy and Climate Research explains: "Initially, hardly anyone would have thought that it would be possible to operate high-temperature fuel cells over such a long period of time." But the Jülich scientists have experienced the opposite with their developed variant of the fuel cell type.
Profitable after five to ten years of operation
Ceramic high-temperature fuel cells achieve the highest efficiencies and are considered to be particularly low-maintenance. The high operating temperature also means high demands on the materials used. Possible areas of application are decentralised power and heat supply in households, in larger residential areas or in industry, as well as systems for trains or ships. High temperature fuel cells must run for 5 to 10 years, or the equivalent of 40,000 to 80,000 hours, in order for their use to be cost-effective.
The Jülich "Solid Oxide Fuel Cell" (SOFC) even lasted much longer. In the long-term experiment, the researchers were the first in the world to demonstrate a service life of 100,000 hours. Since the start of the experiment on August 6, 2007, the stack of cells consisting of two cells has continuously supplied electricity for 93,000 hours, a total of approximately 4,600 kWh. Comparatively, this corresponds roughly to the amount of electricity consumed by a single-family household in a year.
Which effects did the years of stress have on the cell? With the deactivation of SOFC, researchers now have new tasks awaiting them. Externally, the metallic components have changed noticeably over the years. The metallic-silvery shiny surface of the tested fuel cell has become significantly darker, almost black. But apart from this unavoidable superficial oxidation, no negative external changes can be observed.
"We are very excited to see what it looks like inside," says Dr. Norbert Menzler from the Institute for Energy and Climate Research, responsible for the development of ceramic cells. "The state of the cell is hardly visible during operation. So far, nobody in the world has been able to examine a cell after 100,000 operating hours at such high temperatures."
Over the coming weeks and months, the researchers will use various methods to precisely analyze the effects of years of extreme thermal stress on the ceramic components, glass solder seals and metallic connectors, the so-called interconnectors. The results gathered then flow into the development of new materials and design approaches in order to further improve ageing resistance. Scientists led by Professor Ludger Blum are currently testing a reversibly operable version of the solid oxide fuel cell. This not only supplies electricity, but can also generate hydrogen and oxygen through water electrolysis in a reverse operating mode. This further development has already achieved some very good results. It is the first high-temperature fuel cell to achieve an efficiency of over 60% in hydrogen operation with 62%.
This article was first published in German by Elektronikpraxis.