STTR Phase I: Development of High Temperature Membranes for Increased PEM Electrolysis Efficiency

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This Small Business Technology Transfer Phase I Project addresses the efficiency limitations of proton exchange membrane (PEM) electrolysis in order to provide a potentially renewable, cost-competitive hydrogen source for fueling and backup power applications. Proton Energy Systems manufactures PEM electrolyzers which operate at differential pressures ranging from 200 to 2400 psi hydrogen generation. The thickness requirements and temperature limitations of currently used PFSA-membranes result in large ionic resistance losses at the typical operating current densities of 1500 mA/cm2 or greater. Electricity cost is therefore the major contributor to the life cycle cost. In this work, cross-linked poly(sulfone) and poly(phenylene) thermoplastic polymers developed by Penn State University will be utilized to increase mechanical strength and enable higher temperature operation. The research objectives are to 1) synthesize and characterize alternative membrane compositions at thicknesses suitable for high pressure electrolysis applications, 2) incorporate these membranes into MEAs and 3) perform creep studies and electrolysis testing at the single cell stack level at temperatures up to 80 C. By using thinner membranes and higher operating temperatures, the system efficiency can be greatly increased, while the capital cost of the electrolysis unit is decreased. Three families of products will be enhanced or enabled by this research program: (1) PEM electrolysis systems for industrial gas applications, (2) PEM electrolysis systems for transportation fueling applications and (3) PEM electrolysis systems for regenerative fuel cell backup power applications. While all of the product families will benefit from significant cost reduction, the operating cost targets for backup power are the most aggressive. Several fuel cell companies have already been offering backup power packages for this market. However, the typical fueling solution has involved delivered hydrogen. Based on the market analysis Proton has conducted, this is not a practical solution for many wireless sites. The total US backup battery market size has been estimated at ~$250M/year, with the addressable section being ~$130M/year. Proton completed a detailed trade study for DOE which demonstrated that electricity is the largest contributor to the cost of hydrogen via PEM electrolysis, and therefore efficiency gains through higher temperature operation are essential to viability of this application. However, these membrane advances would also benefit the customers of Proton's commercial products in the lab and power plant markets. This study also provides critical information on the viability of non-PFSA membranes for long term electrolysis operation.