Electrolyzers 101: What they are, how they work and where they fit in a green economy

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As Cummins looks to the future, we see a shift in the energy market. With that change comes new possibilities and opportunities beyond our traditional product set. To better serve our customers and our planet, Cummins is innovating new, sustainable forms of power and bringing a wide range of new possibilities to the New Power product portfolio, providing a way to produce clean hydrogen to power hydrogen fuel cells, supply industrial processes or produce green chemicals like fertilizers, renewable natural gas and methanol. 

Cummins offers a variety of hydrogen-based technologies, including electrolyzer systems, and recently announced it will provide its 5-megawatt PEM electrolyzer to convert surplus hydro power to clean hydrogen for the Douglas County Public Utility District in Washington state (USA). But what exactly is an electrolyzer, how does it work and where does it fit in our green economy? 

What is an electrolyzer and how does it work?

Electrolysis - ElectrolyzerAn electrolyzer is a system that uses electricity to break water into hydrogen and oxygen in a process called electrolysis. Through electrolysis, the electrolyzer system creates hydrogen gas. The oxygen that’s left over is released into the atmosphere or can be captured or stored to supply other industrial processes or even medical gases in some cases.

The hydrogen gas can either be stored as a compressed gas or liquefied, and since hydrogen is an energy carrier it can be used to power any hydrogen fuel cell electric application — whether it’s trains, buses, trucks, or data centers. 

In its most basic form, an electrolyzer contains a cathode (negative charge), an anode (positive charge) and a membrane. The entire system also contains pumps, vents, storage tanks, a power supply, separator and other components. Water electrolysis is an electrochemical reaction which takes place within the cell stacks. Electricity is applied to the anode and cathode across the proton exchange membrane (PEM) and causes the water (H20) to split into its component molecules, hydrogen (H2) and oxygen (O2).

Are there different kinds of electrolyzers? 

Yes, they range in size and function. These electrolyzers can be scaled to meet a variety of input and output ranges, ranging in size from small industrial plants installed in shipping containers to large-scale centralized production facilities that can deliver the hydrogen by trucks or be connected to pipelines.

There are three main types of electrolyzers: proton exchange membrane (PEM), alkaline and solid oxide. These different electrolyzers function in slightly different ways depending on the electrolyte material involved. Both alkaline and PEM electrolyzers can deliver on-site and on-demand hydrogen, pressurized hydrogen without a compressor and 99.999% pure, dry and carbon-free hydrogen.

The difference between the three main kinds of electrolyzers include:

Alkaline ElectrolyzerAlkaline Electrolyzers

  • Uses a liquid electrolyte solution such as potassium hydroxide (KOH) or sodium hydroxide (NAOH), and water. 
  • The hydrogen is produced in a “cell” which consists of an anode, cathode and membrane. The cells are typically assembled in series in a “cell stack” that produces more hydrogen and oxygen as the amount of cell increases. 
  • When current is applied on the cell stack, the hydroxide ions (OH-) move through the electrolyte from the cathode to the anode of each cell, with hydrogen gas bubbles generated on the cathode side of the electrolyzer and oxygen gas at the anode, as represented here.

 

Proton Exchange MembraneProton Exchange Membrane (PEM) Electrolyzers

  • PEM electrolyzers use a Proton Exchange Membrane which use a solid polymer electrolyte.
  • When current is applied on the cell stack, the water splits in hydrogen and oxygen and the hydrogen protons pass through the membrane to form H2 gas on the cathode side.

 

 

 

 

Solid Oxide ElectrolyzerSolid Oxide Electrolyzers (SOEC) 

  • Uses solid ceramic material as the electrolyte
  • Electrons from the external circuit combine with water at the cathode to form hydrogen gas and negatively charge ions. Oxygen then passes through the slid ceramic membrane and reacts at the anode to form oxygen gas and generate electrons for the external circuit
  • SOECs operate at a much higher temperature (above 500C) than alkaline and PEM electrolyzers (up to 80C) and have the potential to become much more efficient than PEM and alkaline.

 

How are electrolyzers commercialized based hydrogen production?

There are four main ways that electrolyzers can be commercialized:

  1. Power to mobility: Hydrogen can be used as fuel at refueling stations for fuel-cell electric vehicles such as buses, trains, and car.
  2. Power to Fuel: Be used in refineries to remove sulfur from fossil fuels. 
  3. Power to Industry: Be used directly as an industrial gas in the steel industry, flat glass plants, semi-conductor industry, etc.  It can also be injected directly into the natural gas grids for lower carbon heating and other natural gas applications.
  4. Power to Gas: Be used in the production of green chemicals such as methanol, fertilizers (ammonia) and any other liquid fuel, even jet fuel!  

Electrolyzer - Power to Industry

What’s so unique about hydrogen fuel cells?

The hydrogen produced from an electrolyzer is perfect for use with hydrogen fuel cells. Working much like a battery, fuel cells do not run down or need charging and produce electricity and heat as long as fuel is supplied. You can learn more about batteries and fuel cells here. The fuel cells use the hydrogen to generate electricity with zero emissions at the point of use. That means no fossil fuels or harmful emissions come from the tailpipe.

Even better, when the electrolyzer system is powered by a renewable energy source, such as a hydropower from the Columbia River Dams, the hydrogen produced is considered renewable and CO2-free from well to wheel. Learn more about well to wheel emissions in all-electric and fuel cell applications.

Why is hydrogen such a good option for clean energy?

Hydrogen presents an opportunity for mass market change in the energy industry. Energy systems across the globe are undergoing a fundamental transformation to focus on lower emissions and less negative impact on the environment.

To decrease the negative impacts of climate change and decarbonize the power sector, renewable technologies like wind and solar have emerged as key ingredients to providing a solution. But integrating these intermittent energy sources into the power grid can be challenging.

Hydrogen can act as an energy storage medium to address these grid challenges, allowing renewable power to be more easily used outside the electric power grid. Hydrogen is a stable way to store and transport renewable electricity efficiently over long periods of time. That way, renewable electricity generated by wind and solar that isn’t being used right away can be used another time or in another place. Hydrogen’s potential for storing and transporting energy makes it a key enabler of a global transition to renewable energy.

What is Cummins doing with electrolyzers?

Cummins made a bold entry into the hydrogen economy in September 2019 with the acquisition of Hydrogenics, a global hydrogen fuel cells and electrolyzer technology manufacturer. Cummins continues to make quick progress in innovating new products and applications in the hydrogen space, and currently, there are two different types of electrolyzers offered by Cummins:

  1. The HyLYZER® Polymer Electrolyte Membrane (PEM) Electrolyzer uses an ionically conductive solid polymer and is better suited for large-scale hydrogen production.
  2. The HySTAT® Alkaline Electrolyzer uses a liquid electrolyte and is well-suited for small- to medium-scale hydrogen production. 

Cummins is proud to be leading the charge in new hydrogen technology. With a century of experience in a multitude of power sources and drivetrains, we work with our customers to provide the right solution for the right customer at the right time. Whether it’s battery power, diesel, natural gas or fuel cells, your power is your choice.
 

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Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Cummins New Power President emphasizes decarbonizing now at The New York Times Climate Hub

Cummins New Power President emphasizes decarbonizing now at The New York Times Climate Hub

Amy Davis, Vice President and President of New Power, painted a picture of a decarbonized transportation sector with the help of both battery electric and hydrogen-powered solutions at The New York Times Climate Hub in Glasgow, Scotland, earlier this month. And while the debate between various low- and zero-carbon solutions continues around the world, she urged governments and corporations to start doing something now – because the carbon you put out today, tomorrow and next week cannot be taken back.

Cummins is over 100 years old, and we’ve been powering all kinds of commercial applications. One of the things we know is that [transportation] is very diverse, and we believe it’s not going to take just one solution [to decarbonize it].” – Amy Davis, President of New Power

In parallel with the 2021 United Nations Climate Change Conference, COP26, the Climate Hub hosted its program The Forum.  Over nine days, people across the globe tuned in to 45 live discussions, debates and workshops that addressed the mounting threat of climate change and what actions can be taken to stop it. 

Davis’ presence at The Forum was just one of numerous engagements and initiatives occurring in Glasgow that week. Cummins Chairman and CEO Tom Linebarger also attended COP26, meeting with governments, industry leaders and media to advocate for the shift from fossil fuels to low- and no-carbon solutions and demonstrating how Cummins will be part of the energy transition.

In the days leading to COP26 and The Forum, Cummins was accepted into two influential groups advocating for climate action

The consensus across conversations was that moving toward a carbon-free world is essential – but is it easier said than done? How do we make decarbonization happen? What does decarbonization even look like?

During the Transport and Mobility panel Time and Space: Moving People and Goods in a Carbon-Free World, Davis participated alongside Avinash Rugoobur, President of Arrival; Laura Lane, Chief Corporate Affairs Officer of UPS; and Peter Vanacker, President and CEO of Neste – all transportation and technology companies moving the industry toward a cleaner, greener future.

Watch the full discussion below as The New York Times climate reporter and panel moderator Brad Plumer opens the floor to Davis to discuss why Cummins is approaching decarbonization beyond just electrification, how infrastructure challenges have influenced hydrogen in mobility, and how transitionary periods lead to innovation in aftermarket solutions. 

Watch the full panel:

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From long-range possibilities to innovations happening now, Net Zero News delivers monthly highlights for low-carbon energy. Subscribe today to receive the next issue in your inbox.

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

What is a fuel cell?

Fuel cells are a key technology to unlocking our carbon-neutral future

Fuel cells aren’t new. In fact, the first reference to hydrogen fuel cells appears in 1838 in the December issue of The London and Edinburgh Philosophical Magazine and Journal of Science. Almost 200 years later, the world is recognizing fuel cells as a key technology to unlocking a carbon-neutral future.

Here is what they are, how they work and two fuel cell types that Cummins is investing in.

What is a fuel cell in simple terms?

Like batteries, fuel cells are energy converters – they use an electrochemical reaction to take the chemical energy stored in a fuel source and convert it to electricity. Unlike batteries, which contain a fixed supply of energy, fuel cells do not require recharging. As long as fuel is continuously supplied to the fuel cell, electricity, water and heat will be produced.

How does a fuel cell work?

A fuel cell is comprised of two electrodes and an electrolyte membrane. The electrodes are called a cathode and an anode, and they sandwich the electrolyte membrane between them. Within that system, a series of chemical reactions occur to separate the electrons from the fuel molecules to create energy.

The fuel, typically hydrogen, is fed into the anode on one side while oxygen is fed into the cathode on the other. At the anode, the hydrogen fuel molecules are separated into protons and electrons that will travel different paths toward the cathode. The electrons go through the electrical circuit, creating the flow of electricity. The protons travel through the electrolyte to the cathode. Once at the cathode, oxygen molecules react with the electrons and with the protons to create water molecules.

A fuel cell is a clean energy source with the only byproducts being electricity (power), heat and water. A single fuel cell alone only produces a few watts of power; therefore, several fuel cells can be stacked together to create a fuel cell stack. When combined in stacks, the fuel cells’ output can vary greatly, from just a few kilowatts of power to multi-megawatt installations.

What fuels can be used in fuel cells?

Fuel cells offer flexibility in the fuel type that can be used. While hydrogen is the most common fuel source for fuel cells (hence the common name, hydrogen fuel cells), hydrogen-rich fuels such as natural gas and ammonia are also viable fuel sources.

Hydrogen: When produced using renewable electricity – like solar, wind and hydropower – hydrogen is completely decarbonized and produces zero emissions. Hydrogen fuel cells (i.e. fuel cells that are fueled by hydrogen) produce power, heat and water and release no carbon dioxide or other pollutants into the air.

Natural gas: As widespread production of green hydrogen is still in progress, natural gas is currently the most-used fuel to power fuel cells. In this case the fuel cells are not completely emission-free, but they do offer significantly lower emissions than other fuels, like oil and coal.

Ammonia: Ammonia is most used in agriculture as fertilizer. However, in recent years, several companies have been working to develop green ammonia. Green ammonia is made with hydrogen that comes from water electrolysis powered by alternative energy, making it another option for a low-carbon fuel.

What types of fuel cells is Cummins investing in?

There are six types of fuel cells that are under development, each primarily classified by the kind of electrolyte they employ. Each type of fuel cell has its own advantages, limitations and potential applications. Out of the six, Cummins has recognized the potential in two types of fuel cells – proton exchange membrane fuel cells and solid oxide fuel cells - and has invested in the advancement of their technologies and their application.

Proton exchange membrane (PEM) fuel cells: Also referred to as polymer electrolyte membrane fuel cells, this type of fuel cell uses a polymer electrolyte and operates at lower temperatures of around 80 degrees Celsius. PEM fuel cells are more suitable for mobile and back-up power applications due to their high-power density and quick start-stop capabilities.

Solid oxide fuel cells (SOFCs): SOFCs use a hard, non-porous ceramic compound as their electrolyte and operate at high temperatures, as high as 1,000 degrees Celsius.  This type of fuel cell is most suitable for stationary applications because it is highly efficient and fuel flexible. In addition, waste heat may be harnessed and reused to increase the overall system efficiency.

Why invest in fuel cells?

Already leaders in PEM electrolyzers that produce green hydrogen through electrolysis, we are working on making green hydrogen more readily available for future use in fuel cells. Cummins was awarded a U.S. Department of Energy grant for the advancement of SOFCs and have seen our fuel cells successfully support the operation of battery electric vehicles.

Fuel cells may predate the beginning of Cummins, but we are wasting no time discovering how to advance their technology to create a zero-emission future.

Keep up with alternative power innovation

From long-range possibilities to innovations happening now, Net Zero News delivers monthly highlights for low-carbon energy. Subscribe today to receive the next issue in your inbox.

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

Video Case Study: Cummins HyLYZER® PEM electrolyzer in Bécancour, Quebec

The Cummins HyLYZER in Bécancour, Quebec, Canada, is the largest proton exchange membrane (PEM) electrolyzer in operation in the world. A new video case study highlights the installation’s ground-breaking green hydrogen production capabilities, making it a beacon for a zero-carbon future.

Watch below: 

Commissioned in January and installed at the Air Liquide hydrogen production facility in Quebec, this 20-MW electrolyzer system features industry-leading technology, including four compact, pressurized HyLYZER electrolyzer skids fitted inside the existing building. The systems are modular and scalable, perfect for large-scale utility applications.

Through a phased ramp up, the Cummins HyLYZER system is now at full operation and can produce up to 8.2 tons of low-carbon hydrogen per day — or nearly 3,000 tons of hydrogen annually. It’s powered by the region’s electric grid, which is largely supplied by renewable hydro-electric power. This means the hydrogen produced at the plant is “green” and almost entirely carbon-free.

Through this green hydrogen production, the facility is preventing approximately 27,000 tons of CO2 emissions per year. This is equivalent to taking 10,000 fossil-fueled cars off the road.

Since its commissioning, the system in Bécancour has increased Air Liquide’s hydrogen production capacity by 50%, allowing them to respond to the growing demand for low-carbon fuel in the North American market for both industrial and mobility purposes.

Keep up with alternative power innovation

From long-range possibilities to innovations happening now, Net Zero News delivers monthly highlights for low-carbon energy. Subscribe today to receive the next issue in your inbox.

Cummins Office Building

Cummins Inc.

Cummins is a global power leader that designs, manufactures, sells and services diesel and alternative fuel engines from 2.8 to 95 liters, diesel and alternative-fueled electrical generator sets from 2.5 to 3,500 kW, as well as related components and technology. Cummins serves its customers through its network of 600 company-owned and independent distributor facilities and more than 7,200 dealer locations in over 190 countries and territories.

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