Kathy Ayers | California Institute of Technology (original) (raw)

Papers by Kathy Ayers

Frontiers in Energy Research

Editorial on the Research Topic Advanced water splitting technologies development: Best practices... more Editorial on the Research Topic Advanced water splitting technologies development: Best practices and protocols As the level of deployment and utilization of renewable energy sources, including wind and solar, continues to rise, large-scale, long-term energy storage technologies that could accommodate weekly and seasonal energy fluctuations will play a significant role in the overall deployment of renewable energies in the future. Harnessing and storing renewable energy resources via electrochemical, photoelectrochemical, or thermochemical processes by converting renewable energy into sustainable (energy storage) fuels have the potential to meet the long-term, terawatt scale energy storage challenge. Renewable hydrogen production is the cornerstone for sustainable fuel production and deep decarbonization of multiple sectors in our society. Cost-competitive clean hydrogen provides value to applications, such as 1) in the transportation sector for fuel cell vehicles, 2) in the electric grid sector for system stability and load balancing, and 3) in the industrial sector with metal refineries, cement production, and biomass upgrading (carbon-free fertilizer production). In addition, coupling clean renewable hydrogen with the carbon and nitrogen cycles enables known and wellestablished thermal-chemical processes to generate renewable hydrocarbon fuels and ammonia. The Advanced Water Splitting Technologies (AWST): low temperature electrolysis (LTE), high temperature electrolysis (HTE), photoelectrochemical (PEC) and solar thermo-chemical hydrogen (STCH) provide four unique and parallel approaches to produce low cost, low greenhouse gas (GHG) emission hydrogen at scale (Figure 1). Cost competitive clean hydrogen production using these four technologies is a current high priority focus for governments and industry.

The Electrochemical Society Interface

Proton exchange membrane (PEM) electrolysis was originally developed in the 1950s and 1960s by Ge... more Proton exchange membrane (PEM) electrolysis was originally developed in the 1950s and 1960s by General Electric for space applications to generate oxygen for astronaut life support. Since then, several companies have transitioned the same basic technology to products for hydrogen generation at various scales. Today, PEM water electrolysis has developed into a mature technology for green hydrogen production when integrated with renewable energy. Its advantages include high efficiency, high operating density, fast dynamic response, and the ability to operate at high and differential pressures. However, cost and durability limit the large-scale implementation of PEM electrolyzers. Major components, including catalysts, membranes, and porous transport layers, hold promise for significantly reducing the cost of PEM electrolyzers. Collaborative accelerated stress tests across different labs are highly desirable to study the degradation of PEM electrolyzers and to further improve their dur...

EMN 2B LTE Questionnaire Summary: Includes background and motivation, respondent demographics and... more EMN 2B LTE Questionnaire Summary: Includes background and motivation, respondent demographics and summary of LTE questionnaire responses.

International Journal of Hydrogen Energy, 2021

h i g h l i g h t s High-performance and cost-effective cells are fabricated for water electrolys... more h i g h l i g h t s High-performance and cost-effective cells are fabricated for water electrolysis. Platinum group metal loading is reduced to 1/10th of commercial cell loading. Cells fabricated by reactive spray deposition technology have high durability. Electrodes fabricated by reactive spray deposition technology have high activity.

Energy & Environmental Science, 2021

Understanding the durability-limiting factors of anion exchange membrane water electrolyzers oper... more Understanding the durability-limiting factors of anion exchange membrane water electrolyzers operating under pure water-, KOH- and K2CO3-fed conditions.

ACS Applied Materials & Interfaces, 2021

Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which... more Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which can be used for energy, fertilizer, and industrial applications and thus displace fossil fuels. Pure-water anion-exchange-membrane (AEM) electrolyzers in principle offer the advantages of commercialized proton-exchange-membrane systems (high current density, low cross over, output gas compression, etc.) while enabling the use of less-expensive steel components and nonprecious metal catalysts. AEM electrolyzer research and development, however, has been limited by the lack of broadly accessible materials that provide consistent cell performance, making it difficult to compare results across studies. Further, even when the same materials are used, different pretreatments and electrochemical analysis techniques can produce different results. Here, we report an AEM electrolyzer comprising commercially available catalysts, membrane, ionomer, and gas-diffusion layers operating near 1.9 V at 1 A cm-2 in pure water. After the initial break in, the performance degraded by 0.67 mV h-1 at 0.5 A cm-2 at 55 °C. We detail the key preparation, assembly, and operation techniques employed and show further performance improvements using advanced materials as a proof-of-concept for future AEM-electrolyzer development. The data thus provide an easily reproducible and comparatively high-performance baseline that can be used by other laboratories to calibrate the performance of improved cell components, nonprecious metal oxygen evolution, and hydrogen evolution catalysts and learn how to mitigate degradation pathways.

Current Opinion in Chemical Engineering, 2021

iScience, 2020

Understanding the relationships between porous transport layer (PTL) morphology and oxygen remova... more Understanding the relationships between porous transport layer (PTL) morphology and oxygen removal is essential to improve the polymer electrolyte water electrolyzer (PEWE) performance. Operando X-ray computed tomography and machine learning were performed on a model electrolyzer at different water flow rates and current densities to determine how these operating conditions alter oxygen transport in the PTLs. We report a direct observation of oxygen taking preferential pathways through the PTL, regardless of the water flow rate or current density (1-4 A/cm 2). Oxygen distribution in the PTL had a periodic behavior with period of 400 mm. A computational fluid dynamics model was used to predict oxygen distribution in the PTL showing periodic oxygen front. Observed oxygen distribution is due to low in-plane PTL tortuosity and high porosity enabling merging of oxygen bubbles in the middle of the PTL and also due to aerophobicity of the layer.

ECS Meeting Abstracts, 2020

Hydrogen is an important material for many different applications including materials processing,... more Hydrogen is an important material for many different applications including materials processing, oil refining, ammonia production, energy storage, among many others. In commercial development since the 1950s, proton exchange membrane water electrolyzers (PEMWEs) have been identified as a green source of high-purity hydrogen which can be utilized for many applications [1]. While hydrogen produced by PEMWEs has shown significant promise as a clean hydrogen source for fuels or energy storage, there are a few technical challenges that need to be addressed to allow for its widespread use. One such challenge involves hydrogen crossover. In operation, hydrogen that is formed in the highly pressurized (~400 psi) cathode can diffuse back through the proton exchange membrane and into the anode chamber where oxygen is being formed as a result of the water splitting reaction [2]. This can lead to both performance and safety concerns. With the lower flammability limit (LFL) of hydrogen in oxyge...

ECS Meeting Abstracts, 2018

Sustainable sources of hydrogen are a key need for reducing environmental impact of chemical proc... more Sustainable sources of hydrogen are a key need for reducing environmental impact of chemical processes, with over 95% of hydrogen for industrial applications currently made from fossil fuels through natural gas reforming or coal gasification. Hydrogen is an important industrial gas, representing a 10 million metric tons/year industry worth $100 billion. While proton exchange membrane (PEM)-based water electrolysis has been commercially available for many years, the production scale has been too small until recently to make large impacts. Also, because of the legacy of the technology in life support applications and lower R&D investment relative to PEM fuel cells, there is still significant room for cost and efficiency improvement of PEM electrolysis through materials and manufacturing advancements. This talk will discuss recent work in high efficiency catalysts and membranes and fundamental challenges in translating laboratory tests to manufacturable components. While catalyst compo...

ECS Meeting Abstracts, 2018

Electrochemistry is becoming increasingly important in transitioning from primarily fossil fuel b... more Electrochemistry is becoming increasingly important in transitioning from primarily fossil fuel based energy sources to more renewable options. This challenge will require a combination of solutions, depending on geography, the mix of renewables, and other factors. The intermittent nature of wind, solar, and other forms of renewable energy, as well as demand fluctuations which do not match the generation capacity, drives the need for modular, distributed energy storage solutions, where electrochemistry can be ideal. However, for very long storage times, conversion of energy to a chemical fuel is often the most practical solution. Electrochemical generation of fuels such as hydrogen, ammonia, and CO2-derived hydrocarbons are all related and have similar R&D challenges. In addition, all of these chemicals have different advantages and disadvantages, and have benefits in different scenarios. This talk will focus on some of the considerations in developing a new electrochemical device, ...

ECS Meeting Abstracts, 2017

Membrane (PEM)-based electrolysis provides an ideal near-term technology to address the growing e... more 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 l...

ECS Meeting Abstracts, 2017

One of the biggest challenges in applying hydrogen to energy storage and vehicle fueling applicat... more 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 wi...

ECS Meeting Abstracts, 2015

Proton Energy Systems (d/b/a Proton OnSite) was founded in 1996, based on the premise that hydrog... more Proton Energy Systems (d/b/a Proton OnSite) was founded in 1996, based on the premise that hydrogen generation from proton exchange membrane (PEM)-based electrolysis cells could be made cost competitive versus existing solutions. From small scale laboratory generators, Proton has successfully scaled up products over several design generations. A key advance has been the development of Proton’s C Series, a 30 Nm3/hr or 65 kg/day hydrogen generator based on PEM technology. A building block of this size is more suited for many applications, including common industrial markets and fueling infrastructure for small fleets of cars. This presentation will describe the evolution of Proton’s electrolyzer technology, including improvements in cell stack technology, balance-of-plant scale up, and the strong product platform we have built leading to our next product scale-up effort, for megawatt scale electrolysis applications. Market drivers and applications for various unit capacities, especially the C Series, will also be discussed. Electrolysis based on PEM technology was initially used in space and underwater for life support applications. Reliability is therefore a key characteristic of these systems. Proton has demonstrated over 50,000 hours of continuous operation in house, and has over 2000 systems fielded across product lines, with excellent reliability and up time. An advantage of the PEM systems in general is the ability to generate and electrochemically compress hydrogen at differential pressure, enabling low pressure on the oxygen side of the cell and inexpensive plastic components. The non-corrosive electrolyte also enables low maintenance cost and simpler balance-of-plant. Commercial applications for on-site hydrogen generation are driven by factors such as the desire for low hydrogen inventory, high purity hydrogen requirements, and lack of easily accessible hydrogen delivery infrastructure. Proton’s initial systems were designed to replace helium as the carrier gas in gas chromatographs, or as the lifting gas in weather balloons. The H Series, the precursor to the C Series, was developed specifically to address the electric generator cooling market. Hydrogen is utilized as a cooling fluid for the windings of over 16,000 power plant generators worldwide due to its high heat capacity and low density. Many of these plants are in areas with no reliable hydrogen delivery infrastructure. By 2006, Proton had established a robust cell design leveraging many of the design principles used today. The C Series was developed to serve larger power plants as well as the next level of fueling demonstrations, including small fleets of fuel cell vehicles and fuel cell buses. In addition, it is an appropriate size for heat treating and semiconductor applications. The cell stack, the core technology for the electrochemical system, was originally developed as a replacement for the existing electrolysis stack design for oxygen generation on board submarines. Proton was selected as the preferred developer based on our water electrolysis cell technology knowledge and expertise, leading to the development of a new, larger active area cell stack, including new flow field materials for the hydrogen side of the cell and a thinner cell configuration. This design effort was completed in 18 months, from early 2008 to 2009. Proton is currently under contract to manufacture cell stacks for several submarine platforms. This new cell architecture was then modified for the commercial application, and used as the basis for designing the new C Series system configuration. On the systems side, funding from the U.S. Army / TARDEC led to the development of key balance-of-plant subsystems, such as the implementation of a new gas/water management system, as well as a new high efficiency power supply configuration to drive the cell stacks. Internal investment from Proton paid for the development of system controls, manufacturing processes, and all of the quality documentation and third party agency certification testing required to release this platform as a commercial product. This development effort also spanned about 18 months, from 2009 to early 2011. Currently, Proton is working to translate many of the material advancements from PEM fuel cells to PEM electrolysis cells. While some changes will require modification, there are significant cost savings and efficiency improvements still possible, which Proton has demonstrated to have feasibility. In addition, Proton is performing another scale up effort to launch a megawatt scale product, representing another order of magnitude increase in hydrogen output. These systems will be designed based on requirements for emerging energy markets such as renewable energy capture and biogas methanization, and will also be discussed in this talk. Figure 1

ACS Applied Materials & Interfaces, 2019

Frontiers in Energy Research

Editorial on the Research Topic Advanced water splitting technologies development: Best practices... more Editorial on the Research Topic Advanced water splitting technologies development: Best practices and protocols As the level of deployment and utilization of renewable energy sources, including wind and solar, continues to rise, large-scale, long-term energy storage technologies that could accommodate weekly and seasonal energy fluctuations will play a significant role in the overall deployment of renewable energies in the future. Harnessing and storing renewable energy resources via electrochemical, photoelectrochemical, or thermochemical processes by converting renewable energy into sustainable (energy storage) fuels have the potential to meet the long-term, terawatt scale energy storage challenge. Renewable hydrogen production is the cornerstone for sustainable fuel production and deep decarbonization of multiple sectors in our society. Cost-competitive clean hydrogen provides value to applications, such as 1) in the transportation sector for fuel cell vehicles, 2) in the electric grid sector for system stability and load balancing, and 3) in the industrial sector with metal refineries, cement production, and biomass upgrading (carbon-free fertilizer production). In addition, coupling clean renewable hydrogen with the carbon and nitrogen cycles enables known and wellestablished thermal-chemical processes to generate renewable hydrocarbon fuels and ammonia. The Advanced Water Splitting Technologies (AWST): low temperature electrolysis (LTE), high temperature electrolysis (HTE), photoelectrochemical (PEC) and solar thermo-chemical hydrogen (STCH) provide four unique and parallel approaches to produce low cost, low greenhouse gas (GHG) emission hydrogen at scale (Figure 1). Cost competitive clean hydrogen production using these four technologies is a current high priority focus for governments and industry.

The Electrochemical Society Interface

Proton exchange membrane (PEM) electrolysis was originally developed in the 1950s and 1960s by Ge... more Proton exchange membrane (PEM) electrolysis was originally developed in the 1950s and 1960s by General Electric for space applications to generate oxygen for astronaut life support. Since then, several companies have transitioned the same basic technology to products for hydrogen generation at various scales. Today, PEM water electrolysis has developed into a mature technology for green hydrogen production when integrated with renewable energy. Its advantages include high efficiency, high operating density, fast dynamic response, and the ability to operate at high and differential pressures. However, cost and durability limit the large-scale implementation of PEM electrolyzers. Major components, including catalysts, membranes, and porous transport layers, hold promise for significantly reducing the cost of PEM electrolyzers. Collaborative accelerated stress tests across different labs are highly desirable to study the degradation of PEM electrolyzers and to further improve their dur...

EMN 2B LTE Questionnaire Summary: Includes background and motivation, respondent demographics and... more EMN 2B LTE Questionnaire Summary: Includes background and motivation, respondent demographics and summary of LTE questionnaire responses.

International Journal of Hydrogen Energy, 2021

h i g h l i g h t s High-performance and cost-effective cells are fabricated for water electrolys... more h i g h l i g h t s High-performance and cost-effective cells are fabricated for water electrolysis. Platinum group metal loading is reduced to 1/10th of commercial cell loading. Cells fabricated by reactive spray deposition technology have high durability. Electrodes fabricated by reactive spray deposition technology have high activity.

Energy & Environmental Science, 2021

Understanding the durability-limiting factors of anion exchange membrane water electrolyzers oper... more Understanding the durability-limiting factors of anion exchange membrane water electrolyzers operating under pure water-, KOH- and K2CO3-fed conditions.

ACS Applied Materials & Interfaces, 2021

Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which... more Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which can be used for energy, fertilizer, and industrial applications and thus displace fossil fuels. Pure-water anion-exchange-membrane (AEM) electrolyzers in principle offer the advantages of commercialized proton-exchange-membrane systems (high current density, low cross over, output gas compression, etc.) while enabling the use of less-expensive steel components and nonprecious metal catalysts. AEM electrolyzer research and development, however, has been limited by the lack of broadly accessible materials that provide consistent cell performance, making it difficult to compare results across studies. Further, even when the same materials are used, different pretreatments and electrochemical analysis techniques can produce different results. Here, we report an AEM electrolyzer comprising commercially available catalysts, membrane, ionomer, and gas-diffusion layers operating near 1.9 V at 1 A cm-2 in pure water. After the initial break in, the performance degraded by 0.67 mV h-1 at 0.5 A cm-2 at 55 °C. We detail the key preparation, assembly, and operation techniques employed and show further performance improvements using advanced materials as a proof-of-concept for future AEM-electrolyzer development. The data thus provide an easily reproducible and comparatively high-performance baseline that can be used by other laboratories to calibrate the performance of improved cell components, nonprecious metal oxygen evolution, and hydrogen evolution catalysts and learn how to mitigate degradation pathways.

Current Opinion in Chemical Engineering, 2021

iScience, 2020

Understanding the relationships between porous transport layer (PTL) morphology and oxygen remova... more Understanding the relationships between porous transport layer (PTL) morphology and oxygen removal is essential to improve the polymer electrolyte water electrolyzer (PEWE) performance. Operando X-ray computed tomography and machine learning were performed on a model electrolyzer at different water flow rates and current densities to determine how these operating conditions alter oxygen transport in the PTLs. We report a direct observation of oxygen taking preferential pathways through the PTL, regardless of the water flow rate or current density (1-4 A/cm 2). Oxygen distribution in the PTL had a periodic behavior with period of 400 mm. A computational fluid dynamics model was used to predict oxygen distribution in the PTL showing periodic oxygen front. Observed oxygen distribution is due to low in-plane PTL tortuosity and high porosity enabling merging of oxygen bubbles in the middle of the PTL and also due to aerophobicity of the layer.

ECS Meeting Abstracts, 2020

Hydrogen is an important material for many different applications including materials processing,... more Hydrogen is an important material for many different applications including materials processing, oil refining, ammonia production, energy storage, among many others. In commercial development since the 1950s, proton exchange membrane water electrolyzers (PEMWEs) have been identified as a green source of high-purity hydrogen which can be utilized for many applications [1]. While hydrogen produced by PEMWEs has shown significant promise as a clean hydrogen source for fuels or energy storage, there are a few technical challenges that need to be addressed to allow for its widespread use. One such challenge involves hydrogen crossover. In operation, hydrogen that is formed in the highly pressurized (~400 psi) cathode can diffuse back through the proton exchange membrane and into the anode chamber where oxygen is being formed as a result of the water splitting reaction [2]. This can lead to both performance and safety concerns. With the lower flammability limit (LFL) of hydrogen in oxyge...

ECS Meeting Abstracts, 2018

Sustainable sources of hydrogen are a key need for reducing environmental impact of chemical proc... more Sustainable sources of hydrogen are a key need for reducing environmental impact of chemical processes, with over 95% of hydrogen for industrial applications currently made from fossil fuels through natural gas reforming or coal gasification. Hydrogen is an important industrial gas, representing a 10 million metric tons/year industry worth $100 billion. While proton exchange membrane (PEM)-based water electrolysis has been commercially available for many years, the production scale has been too small until recently to make large impacts. Also, because of the legacy of the technology in life support applications and lower R&D investment relative to PEM fuel cells, there is still significant room for cost and efficiency improvement of PEM electrolysis through materials and manufacturing advancements. This talk will discuss recent work in high efficiency catalysts and membranes and fundamental challenges in translating laboratory tests to manufacturable components. While catalyst compo...

ECS Meeting Abstracts, 2018

Electrochemistry is becoming increasingly important in transitioning from primarily fossil fuel b... more Electrochemistry is becoming increasingly important in transitioning from primarily fossil fuel based energy sources to more renewable options. This challenge will require a combination of solutions, depending on geography, the mix of renewables, and other factors. The intermittent nature of wind, solar, and other forms of renewable energy, as well as demand fluctuations which do not match the generation capacity, drives the need for modular, distributed energy storage solutions, where electrochemistry can be ideal. However, for very long storage times, conversion of energy to a chemical fuel is often the most practical solution. Electrochemical generation of fuels such as hydrogen, ammonia, and CO2-derived hydrocarbons are all related and have similar R&D challenges. In addition, all of these chemicals have different advantages and disadvantages, and have benefits in different scenarios. This talk will focus on some of the considerations in developing a new electrochemical device, ...

ECS Meeting Abstracts, 2017

Membrane (PEM)-based electrolysis provides an ideal near-term technology to address the growing e... more 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 l...

ECS Meeting Abstracts, 2017

One of the biggest challenges in applying hydrogen to energy storage and vehicle fueling applicat... more 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 wi...

ECS Meeting Abstracts, 2015

Proton Energy Systems (d/b/a Proton OnSite) was founded in 1996, based on the premise that hydrog... more Proton Energy Systems (d/b/a Proton OnSite) was founded in 1996, based on the premise that hydrogen generation from proton exchange membrane (PEM)-based electrolysis cells could be made cost competitive versus existing solutions. From small scale laboratory generators, Proton has successfully scaled up products over several design generations. A key advance has been the development of Proton’s C Series, a 30 Nm3/hr or 65 kg/day hydrogen generator based on PEM technology. A building block of this size is more suited for many applications, including common industrial markets and fueling infrastructure for small fleets of cars. This presentation will describe the evolution of Proton’s electrolyzer technology, including improvements in cell stack technology, balance-of-plant scale up, and the strong product platform we have built leading to our next product scale-up effort, for megawatt scale electrolysis applications. Market drivers and applications for various unit capacities, especially the C Series, will also be discussed. Electrolysis based on PEM technology was initially used in space and underwater for life support applications. Reliability is therefore a key characteristic of these systems. Proton has demonstrated over 50,000 hours of continuous operation in house, and has over 2000 systems fielded across product lines, with excellent reliability and up time. An advantage of the PEM systems in general is the ability to generate and electrochemically compress hydrogen at differential pressure, enabling low pressure on the oxygen side of the cell and inexpensive plastic components. The non-corrosive electrolyte also enables low maintenance cost and simpler balance-of-plant. Commercial applications for on-site hydrogen generation are driven by factors such as the desire for low hydrogen inventory, high purity hydrogen requirements, and lack of easily accessible hydrogen delivery infrastructure. Proton’s initial systems were designed to replace helium as the carrier gas in gas chromatographs, or as the lifting gas in weather balloons. The H Series, the precursor to the C Series, was developed specifically to address the electric generator cooling market. Hydrogen is utilized as a cooling fluid for the windings of over 16,000 power plant generators worldwide due to its high heat capacity and low density. Many of these plants are in areas with no reliable hydrogen delivery infrastructure. By 2006, Proton had established a robust cell design leveraging many of the design principles used today. The C Series was developed to serve larger power plants as well as the next level of fueling demonstrations, including small fleets of fuel cell vehicles and fuel cell buses. In addition, it is an appropriate size for heat treating and semiconductor applications. The cell stack, the core technology for the electrochemical system, was originally developed as a replacement for the existing electrolysis stack design for oxygen generation on board submarines. Proton was selected as the preferred developer based on our water electrolysis cell technology knowledge and expertise, leading to the development of a new, larger active area cell stack, including new flow field materials for the hydrogen side of the cell and a thinner cell configuration. This design effort was completed in 18 months, from early 2008 to 2009. Proton is currently under contract to manufacture cell stacks for several submarine platforms. This new cell architecture was then modified for the commercial application, and used as the basis for designing the new C Series system configuration. On the systems side, funding from the U.S. Army / TARDEC led to the development of key balance-of-plant subsystems, such as the implementation of a new gas/water management system, as well as a new high efficiency power supply configuration to drive the cell stacks. Internal investment from Proton paid for the development of system controls, manufacturing processes, and all of the quality documentation and third party agency certification testing required to release this platform as a commercial product. This development effort also spanned about 18 months, from 2009 to early 2011. Currently, Proton is working to translate many of the material advancements from PEM fuel cells to PEM electrolysis cells. While some changes will require modification, there are significant cost savings and efficiency improvements still possible, which Proton has demonstrated to have feasibility. In addition, Proton is performing another scale up effort to launch a megawatt scale product, representing another order of magnitude increase in hydrogen output. These systems will be designed based on requirements for emerging energy markets such as renewable energy capture and biogas methanization, and will also be discussed in this talk. Figure 1

ACS Applied Materials & Interfaces, 2019