Oriented thin films of La 0.5 Sr 0.5 CoO 3-x were deposited on single-crystal 9.5 mol% Y 2 O 3 stabilized ZrO 2 by laser deposition. The films were infused with 18 O by exchange with 20 kPa O 2 at 300-400°C, then quenched and depth profiled by secondary ion mass spectroscopy. Analysis of the depth profiles revealed a significant barrier to interfacial transport at these relatively low temperatures.

Isotope exchange with C18O2 followed by depth profiling analysis was used to study surface exchange and bulk diffusion of oxygen in single crystal ((100) surface orientation) yttria-stabilized zirconia (YSZ) in the temperature range 250°C - 350°C. The depth profiles, which were obtained using 18O(ρ,α)15N nuclear reaction analysis (NRA) and secondary ion mass spectrometry (SIMS), reveal both the bulk oxygen diffusion coefficients (D) and surface exchange coefficients (k). Bulk oxygen diffusion coefficients are consistent with an extrapolation to lower temperature of previously published results with an activation energy of 114 kJ/mol (1.2 eV). The surface exchange rates, however, depend strongly on the gas exchange species. Much higher exchange rates are observed with C18O2 than with 18O2 (over four orders of magnitude when compared to an extrapolation to lower temperatures of previously published results) with a measured activation energy of 152 kJ/mol (1.6 eV). This faster surface exchange rate enabled measurable 18O tracer profiles to be generated at lower temperatures than previously reported, further contributing to the understanding of YSZ material properties and bringing to light a possible order/disorder transition similar to that previously observed at 650°C.

Keywords: PEM Electrolyzer, Power to Gas, Mega Watt (MW) In future energy systems with high percentages of fluctuating renewable energy generation, electricity storage will become increasingly important for the utilization of surplus energy. Among several electricity storage options, the Power to Gas technology is one promising option for solving the challenge of long-term electricity storage [1]. In this approach, excess renewable energy is converted via water electrolysis to hydrogen and used directly as an energy storage medium or it can go thru further conversion to methane [2]. To fully utilize the potential of Power to Gas, large-scale technology implementation should be accelerated so the costs are driven down. PEM electrolyzers need to become quickly available on multi-mega watt (MW) scale [3]. Hydrogenics has been developing water electrolysis technology based on proton exchange membrane (PEM) since the late 1990s. Driven by Power to Gas applications and corresponding cost modeling, Hydrogenics increased the scale of its PEM water electrolysis stack and launched its new MW scale electrolysis platform in 2014. This MW scale platform is still the most compact, highest capacity PEM electrolyzer cell stack in the world and capable of absorbing 3 MW of electricity with a single stack. To date, Hydrogenics has delivered numerous MW systems globally, with the majority of them in Power to Gas, renewable energy storage and grid balancing applications. Hydrogenics is developing the next-generation systems with continuing focus on cost reduction through technology innovation and scale up. With the market introduction of a single 3 MW stack, Hydrogenics continues to demonstrate that its hydrogen-based energy storage technology will transform the energy sector by providing ancillary and grid balancing services to grid operators while converting large scale renewable energy at a utility scale. References: Jentscha, T. Trosta, M. Sternerb, Optimal Use of Power-to-Gas Energy Storage Systems in an 85% Renewable Energy Scenario, Energy Procedia 46 ( 2014 ) 254 – 261 Power-to-Gas: The Case for Hydrogen White Paper, Califonia Hydrogen Business Council, 2015 Schulze, J. Holstein, A. Noort and J. Knijp, Power-to-gas in a Decarbonized European Energy System Based on Renewable Energy Sources, European Power to Gas White Paper