Proton OnSite’s latest project with the US Department of Energy (DOE) has yielded a proton exchange membrane (PEM) electrolyzer stack that can produce hydrogen gas at the pressure required to fuel a vehicle, without the need for a compressor.
A high-differential pressure PEM stack can now safely generate hydrogen gas at 5,000 psi (344 bar) without the need for a compressor, while releasing the outgoing oxygen gas at atmospheric pressure. Proton OnSite began collaborating with the DOE in February 2010 on Phase I of the project. With this achievement, Proton OnSite will successfully end Phase II in August 2012.
Currently, fuel cell buses and some passenger cars require hydrogen gas at 5,000 psi, which is attained by attaching a compressor to the refueler. Attaining this level without a compressor brings refueling stations a step closer to forgoing this capital- and maintenance-intensive piece of equipment. This would allow stations to pass these savings onto drivers of fuel cell vehicles through lower fuel costs.
PEM electrolyzers work by running a current through a solid polymer electrolyte, which through electrolysis draws a hydrogen ion (proton) from deionized water and through the membrane. These ions combine at the other end of the membrane to produce hydrogen gas, leaving oxygen on the other side. Manufacturers who are currently developing fuel cells for automobiles are using this same PEM technology in reverse.