Water electrolysis has benefits over other hydrogen generation technologies due to the lack of carbon footprint when integrated with a renewable source of energy. Specifically, proton exchange membrane (PEM) electrolysis is a promising technology for hydrogen generation applications because of the lack of corrosive electrolytes, small footprint, and ability to generate at high pressure, requiring only deionized water and an energy source. PEM electrolysis also produces very pure hydrogen, with none of the typical catalyst poisons that may be found in hydrogen produced from reforming. However, significant advances are required in order to in order to provide a cost-competitive hydrogen source for energy markets. This paper will discuss the current limitations and recent work by Proton Energy Systems towards reaching the DOE Hydrogen Program objective for distributed production of hydrogen from distributed water electrolysis of $3.70/gge by 2012. Status of TechnologyProton exchange membrane (PEM) electrolysis has been known for over 50 years, starting from GE technology. Proton Energy Systems is currently the world leader in manufacturing of PEM hydrogen generation products using electrolysis, with over 1300 units in the field. Pure hydrogen is used in a variety of industrial applications, including acting as a cooling fluid for power plant turbine generators, a reducing atmosphere for heat treating and semiconductor processing, and as a carrier gas for spectroscopic applications such as gas chromatography. Proton's on site hydrogen generators are costcompetitive with delivered hydrogen for these applications. However, interest in hydrogen for energy applications has increased the need to decrease capital cost and increase efficiency of electrolysis and other generation methods. PEM vs. AlkalineThere are two main types of low temperature electrolysis currently commercially available. Alkaline electrolysis uses liquid electrolyte, with high concentrations of potassium hydroxide to provide ionic conductivity and to participate in the electrochemical reactions. PEM electrolysis replaces the liquid electrolyte with a solid polymer electrolyte, which selectively conducts positive ions such as protons. The protons participate in the water-splitting reaction instead of hydroxide, creating a locally acidic environment in the cell.There are advantages and disadvantages of each system. One advantage of KOH electrolyzers is the stability of nickel and stainless steel in this environment, enabling elimination of expensive materials of construction. However, in the KOH system, the

Alkaline stability of benzyl trimethylammonium (BTMA)-functionalized polyaromatic membranes was investigated by computational modeling and experimental methods. The barrier height of hydroxide initiated aryl-ether cleavage in the polymer backbone was computed to be 85.8 kJ/mol, a value lower than the nucleophilic substitution of the αcarbons on the benzylic position of BTMA cationic functional group, computed to be 90.8 kJ/mol. The barrier heights of aryl− aryl cleavage (polymer backbone) are 223.8−246.0 kJ/mol. The computational modeling study suggests that the facile aryl−ether cleavage is not only due to the electron deficiency of the aryl group but also due to the low bond dissociation energy arising from the ether substituent. Ex situ degradation studies using Fourier transform infrared (FTIR) and 1 H nuclear magnetic resonance (NMR) spectroscopy indicated that 61% of the aryl−ether groups degraded after 2 h of treatment in 0.5 M NaOH at 80 °C. BTMA cationic groups degraded slowly over 48 h under the same conditions. In situ degradation studies validate the calculated results: anion exchange membrane fuel cells and water electrolyzer using poly(arylene ether) membranes exhibit a catastrophic, premature failure during lifetime tests, while no sudden performance loss is observed with an ether-free poly(phenylene) membrane. Despite the gradual performance loss due to the degradation of BTMA cation functional group, the membrane electrode assembly using the poly(phenylene) membrane exhibited a lifetime of >2000 h in the alkaline water electrolyzer mode at 50 °C.

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Proton exchanges membrane (PEM) regenerative fuel cell electrolysis of water is of great recent interest as a hydrogen generation technology. Anode side titanium current collectors and separator plates used in these applications typically employ coatings of platinum group metals to achieve durability and performance requirements in the high voltage, oxidizing environment. The present work assessed the potential for lower cost surface modified titanium by both thermal (gas) nitridation and plasma nitridation approaches. The nitrided Ti was found to result in far less hydrogen uptake in coupon testing than did Pt-plated Ti. Short-term (48 h) single-cell performance at 25 °C was approximately 13% better (lower voltage) at 1.2 A/cm 2 for thermal and plasma nitrided plates vs untreated Ti. However, at 50°C and 1.5 A/cm 2 , the thermally nitrided plate exhibited only on the order of 3% better behavior (lower voltage) compared to the untreated Ti and plasma nitrided Ti. Durability testing for 500 h resulted in only a minor degradation in cell performance, on the order of 1-2% voltage increase, with the best behavior exhibited by the thermally nitrided Ti plate. Despite their relatively stable cell performance, extensive local oxidation of the thermally nitrided and plasma nitrided flow field regions was observed.

Carbon-free energy generation is a necessity to meet rising global energy needs while minimizing environmental impact. Hydrogen has the potential to be a cost competitive and scalable solution to replace fossil fuels, and water electrolysis is an attractive concept for producing hydrogen with zero carbon footprint when integrated with a renewable energy source. Proton Energy Systems is a world leader in hydrogen generation from PEM electrolysis and has demonstrated the commercial viability of this technology in the industrial gas market, with pathways defined to reach targets in the energy markets. Recent catalyst research at Proton has demonstrated efficiency improvements while maintaining stability. Ongoing collaboration with 3M has also shown feasibility to reduce the catalyst loading by over an order of magnitude vs. current commercial loadings. This paper will discuss Proton's fueling efforts, particularly at high pressure, and advancements in efficiency which enable localized generation of hydrogen where it is needed.