By using high-temperature proton exchange membranes (HT-PEM) in fuel cells, hydrogen purity is no longer a problem. It is even possible to use any fuel with H2 molecules. This also saves weight in heavy vehicles.
Because they operate at relatively low temperatures, conventional PEM membrane fuel cells require perfect hydrogen purity. In the United States, a partnership has just been formed around the Los Alamos National Laboratory to develop and market fuel cells using high-temperature proton exchange membranes. The technology, which is intended for heavy-duty vehicles, is based on a different membrane-electrode assembly developed by the Los Alamos National Laboratory. It will no longer be based on water, but on a polymer. Thanks to this, HT-PEM PACs can operate reliably over a wider range of high temperatures, between 80 and 200° C.
A lighter system
Several important benefits would result from the adoption of these membranes, the first of which would be to no longer have to worry about the heat release that typically accompanies power generation in fuel cells.
“In high-temperature operation, we can build heavy-duty trucks with a much simpler design, which allows us to reduce weight significantly,” adds Yu Seung Kim, a scientist at the Los Alamos lab. The biggest gain would be in the tanks. Today, for a range of more than 550 kilometers, road tractors must carry H2 containers weighing around 1,800 kg. With the future HT-PEM fuel cells, the weight of the tanks could be reduced by more than 650 kg.
A multitude of fuels
Why this reduction in tank weight? Simply because HT-PEM cells, in addition to pure hydrogen, can operate with any fuel containing H2 molecules. It becomes possible to use liquid fuels with high energy density.
The applications are numerous for mobility. Vessels can run on methanol or renewable ammonia. Methoxymethane, or dimethyl ether, would be preferred in aviation. That’s why the U.S. Department of Energy, through its Office of Hydrogen and Fuel Cell Technologies, is financially supporting the project.
Partners’ roles
Los Alamos National Laboratory’s knowledge of HT-PEM membranes will be transferred to the Renewable Energy Laboratory, which will be responsible for developing the process for mass production of membrane-electrode assemblies. Brookhaven National Laboratory will work on oxygen reduction catalysts. Finally, Advent Technology, a company focused on fuel cell and hydrogen technology innovation, will be responsible for confirming the performance and durability of the system in industrial-scale production and then delivering commercially viable HT-PEM fuel cells.