Proton OnSite (United States)

One of the biggest challenges in applying hydrogen to energy storage and vehicle fueling applications is to efficiently store the hydrogen in a small volume with high reliability equipment. High pressure hydrogen applications that are used at a high duty cycle, including vehicle fueling demonstrations, repeatedly show that mechanical compression is one of the highest maintenance devices in the system. Electrochemical compression requires no moving parts within the cell, resulting in less maintenance due to wear, and also is highly efficient, with very low voltage penalty. The primary efficiency loss in electrochemical compression of hydrogen at high pressure is due to back diffusion of the compressed gas to the other cell chamber. Still, the overall efficiency still competes very well with mechanical compression to thousands of psi, as will be shown in this talk. Proton exchange membrane (PEM)-based electrolysis enables combining the generation of hydrogen through water-splitting with the direct electrochemical compression of the gas. These membrane-based systems also have the advantage that they are capable of differential pressure operation. While there are applications for both pressurized oxygen and hydrogen, the differential pressure capability is especially attractive for generating high pressure hydrogen while maintaining the water-oxygen loop at ambient pressure, due to the inherent safety risks of high pressure oxygen. Proton OnSite, the market leader in PEM electrolysis, has been increasing the proven output pressure of PEM electrolyzer devices, with demonstration of 350-bar (5,000 psi) hydrogen generation and 250-bar (3600 psi) oxygen generation, both in full differential pressure mode (see Figure). The hydrogen cell stack has been scaled to a capacity of 4.5 kg/day and is certified to meet the relevant codes and standards. This talk will address the challenges and successes for both hydrogen and oxygen compression at Proton, and potential best fits for these technologies. Figure 1

Membrane (PEM)-based electrolysis provides an ideal near-term technology to address the growing energy storage demands as intermittent renewable energy becomes more prevalent. While proton exchange membrane (PEM) systems are often viewed as preferred solutions to legacy KOH systems due to the lack of corrosive electrolyte, small footprint, and dynamic operating range due to the ability of the PEM systems to generate hydrogen at differential pressure, they still present capital cost challenges. In particular, the platinum group metal catalysts and valve metals for separator and flow field construction required for stability in the acidic environment become a significant cost driver at scale. Alkaline exchange membrane (AEM)-based electrolysis is therefore viewed as a potential replacement to the current PEM systems as a means of driving down the high capital cost. This cost reduction is accomplished by replacing the typical high cost catalyst and materials of cell construction with lower cost metals that would corrode in the acidic PEM environments, but are stable in the alkaline chemistries. In theory, this approach is highly promising, but testing of the current state-of the art has shown the technology gaps between the two platforms in terms of stability, durability, and operating electrical efficiency. Modeling has shown that savings realized in capital cost are typically off-set by an increase in operating expense resulting from the lower activity of the non-PGM catalysts and poor conductivity of the AEM. Additionally, thermal instability of the AEMs require stacks to be operated at lower temperatures than a typical PEM system, impacting conductivity further and slowing kinetics. The addition of liquid electrolyte to the water feed has been shown by some groups to be effective in reducing cell operating potentials and providing overall voltage stability. However, this solution adds management and additional maintenance of handling the caustics typically used. Efforts at Proton have shown significant improvements in operation under milder conditions, showing some potential to achieve targets required to compete with incumbent technology. In this talk, some of the advancements achieved and how these have impacted the cost of the hydrogen will be discussed. An example of this improvement is shown in the figure below, where collaborative ionomer research and partnering with a commercial entity for scale-up of catalyst synthesis have translated into an immediate improvement over targets previously established. Additionally, cost models will be compared to show the path needed to establish equivalence with current PEM systems and what is required to go beyond. Figure 1

The growing need to store increasing amounts of renewable energy has recently triggered substantial R&D efforts towards efficient and stable water electrolysis technologies. The oxygen evolution reaction (OER) occurring at the electrolyser anode is central to the development of a clean, reliable and emission-free hydrogen economy. The development of robust and highly active anode materials for OER is therefore a great challenge and has been the main focus of research. Among potential candidates, perovskites have emerged as promising OER electrocatalysts. In this study, by combining a scalable cutting-edge synthesis method with time-resolved X-ray absorption spectroscopy measurements, we were able to capture the dynamic local electronic and geometric structure during realistic operando conditions for highly active OER perovskite nanocatalysts. Ba0.5Sr0.5Co0.8Fe0.2O3-δ as nano-powder displays unique features that allow a dynamic self-reconstruction of the material's surface during OER, that is, the growth of a self-assembled metal oxy(hydroxide) active layer. Therefore, besides showing outstanding performance at both the laboratory and industrial scale, we provide a fundamental understanding of the operando OER mechanism for highly active perovskite catalysts. This understanding significantly differs from design principles based on ex situ characterization techniques.

Proton exchange membrane water electrolysis (PEMWE) offers several advantages over other electrolysis technologies including greater energy efficiency, higher production rates, dynamic responses and more compact design. [1] High loading is a major barrier to the path of large-scale production of PEMWE. [2] The state-of-the-art anode catalysts in conventional PEMWEs are mixed iridium and iridium oxides (IrOx) with typical iridium loading from 1 to 3 mg cm-2, which is too high to meet the long term cost target for energy markets [2]. Meanwhile, translation of catalyst development from lab scale to the megawatt scale remains challenging in terms of electrode stability. [3] Herein, a composite catalyst layer of iridium oxide/Nafion (IrOx/Nafion) is developed using reactive spray deposition technology (RSDT) which combines the catalyst synthesis and catalyst-coated membrane (CCM) fabrication into one step. The RSDT-derived IrOx/Nafion showed distinctive features that are beneficial to the oxygen evolution reaction (OER) activity and durability. The iridium particles were about 1-2 nm with very high surface area due to the intrinsic property of resistance to sintering [4]. This resulted in high anodic charge proportional to the oxide surface area and superior activity over planar and electrodeposited IrO2thin films. The OER activity can be further enhanced by increasing the amount of surface oxide of iridium which was achieved by increasing the flame length, flame temperature and oxygen flow rate. In Figure 1, F-1 and F-2 corresponds two different flame conditions with iridium surface oxide percentage of 28% and 100%, respectively. Higher surface oxide percentage (F-2) resulted in superior anodic charge (Figure 1a) and OER activity (Figure 1 b,c). The electrolyzer durability of the RSDT-derived IrOx/Nafion catalyst layer was optimized by increasing the amount of iridium oxide on the iridium particle surface and by decreasing the number of IrOx/Nafion agglomerates on the catalyst layer surface. Ongoing studies of CCMs fully fabricated by the RSDT process showed promising electrolyzer durability of 3300 hours (Figure 1d). Analysis of post-durability test samples will be conducted to investigate the effect of long-term operation on catalyst layer integrity and iridium dissolution and migration in the electrolyte membrane. Figure 1. Cyclic voltammetry (CV) of RSDT-derived IrOx/Nafion catalyst with two flame conditions (a). CV recorded in nitrogen-purged 0.1M HClO4 at 25 oC with 20 mV/s scan rate from 0.0 V to 1.5V (vs. RHE). Quasi-stationary polarization curves for OER recorded from 1.45-1.69 V vs. RHE with 20 mV step and 5 min dwell time (b). (c) Compares the OER mass activity and specific activity of RSDT-derived IrOx/Nafion catalysts and pure IrO2 (adapted from [5]) tested with the same procedure. (d) Shows the electrolyzer MEA durability test of RSDT-derived cathode and anode. Test performed using a circular 86 cm2 cell at 80 oC with 1.8 A cm-2current load and 400 psi hydrogen pressure.

Renewable hydrogen is becoming an increasingly important component of the transition away from fossil fuel use and towards reduction in carbon dioxide production. Hydrogen is the intermediary between primary energy sources and end products in many chemical processes such as ammonia generation, refining, and biogas processing, and is currently mainly produced by reforming of natural gas. Hydrogen from electrolysis can both make a strong environmental impact on these industries and also improve utilization of intermittent renewable energy sources such as wind and solar by leveraging otherwise stranded resources. Proton exchange membrane (PEM) electrolysis is especially well suited to energy capture because of the dynamic range and ability to quickly ramp up and down from near zero output to full capacity. This paper will discuss the challenges in continued scale up, translating laboratory scale findings to commercial PEM systems as well as some of recent advancements and impact on cost.

Abstract Advanced electrolysis hydrogen technology has demonstrated utility in providing hydrogen for brazing, annealing, MIM, P/M, flame spray and other thermal treatment techniques, in both continuous and batch modes. Advantages include low flammable inventory, elimination of pressure hazards, eliminating of the need to move cylinders and elimination of deliveries. By combining on-site hydrogen generation with a small amount of in-process hydrogen surge storage, on-site hydrogen generation can be used to meet the needs of batch process such as batch furnaces. By carefully choosing generation pressure and surge storage vessel volume, the process can provide maximum flexibility while minimizing the amount of hydrogen actually stored. As compared with dissociated ammonia, advanced electrolysis hydrogen generation provides drier gas, and the ability to vary furnace atmosphere from no hydrogen to 100% hydrogen, enhancing processing flexibility. Additionally, advanced electrolysis can be turned off when not in use saving power as compared with ammonia retorts.

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Water based electrolyzers offer a promising approach for generating hydrogen gas for renewable energy storage. 3M's nanostructured thin film (NSTF) catalyst technology platform has been shown to significantly reduce many of the performance, cost and durability barriers standing in the way of H2/air PEM fuel cells for vehicles. In this paper we describe results from the first evaluations of low loaded NSTF catalysts in H2/O2 electrolyzers at Proton OnSite and Giner, Inc. Over two dozen membrane electrode assemblies comprising nine different NSTF catalyst types were tested in 11 short stack durability tests at Proton OnSite and 14 performance tests in 50 cm2 single cells at Giner Electrochemical Systems. NSTF catalyst alloys of Pt68Co29Mn3, Pt50Ir50 and Pt50Ir25Ru25, with Pt loadings in the range of 0.1 to 0.2 mg/cm2, were investigated for beginning-of-life performance and durability up to 4000 hours as both electrolyzer cathodes and anodes. Catalyst composition, deposition and process conditions were found to be important for meeting the performance of standard PGM blacks on electrolyzer anodes while using only 10% as much PGM catalyst. Analyses of MEA's after the durability tests by multiple techniques document changes in catalyst alloy composition, loading, crystallite structure and support stability.