The Next Step Towards a Hydrogen EconomyModern Motivations for Moving to Water Electrolyzers

The Next Step Towards a Hydrogen Economy 2

A growing number of international and regional regulations now mandate reductions in greenhouse gas emissions. Thus, hydrogen has become a serious marketplace contender as a low-carbon energy source.

CEOs from 39 international energy, transportation, and industrial companies formed the Hydrogen Council.¹ This council envisions using hydrogen to replace gasoline

as a transport fuel, natural gas for heating, and fossil fuels for generating electricity needed to meet energy requirements of homes, offices, and factories.

By 2030, the Hydrogen Council members believe that approximately 230-250 TWh of surplus solar and wind energy could be converted to hydrogen.

Global Regulations and Businesses Push for Cleaner Energy

¹Source: http://hydrogencouncil.com/

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Increasing Demand for Clean and Scalable Hydrogen Production

Whether hydrogen is burned to produce heat or converted to electricity in a fuel cell, its only by-product is water—making it an attractive source for clean energy. In fact, the hydrogen generation market is predicted to grow at a compound annual growth rate (CAGR) of 5.8% through 2025.² This estimate may be conser-vative based on the market’s increased focus on cleaner energy, favorable government reg-ulations, and other landscape-shifting trends driving expansion.

However, traditional methods of hydrogen production via steam or oil reforming and coal gasification result in significant greenhouse gas emissions. Stringent regulations designed to control the use of these fossil fuels will likely influence the market to find cleaner production methods more quickly. It’s imperative to find sustainable production methods at scale.

Electricity from renewable sources can also be used to produce hydrogen, which represents a win-win for clean energy because:

• Using hydrogen with renewable wind and solar electricity generation helps meet emis-sion regulations

• Excess hydrogen can be stored and convert-ed to clean energy via fuel cells when renew-ables don’t produce enough electricity flow

Additionally, the growing market for fuel cell cars (electric vehicles powered by hydrogen) will continue to boom, further increasing the demand for clean energy production.³

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²Source: https://www.grandviewresearch.com/industry-analysis/hydrogen-generation-market

³Source: https://www.marketwatch.com/press-release/global-hydrogen-fuel-cell-vehicle-market-to-grow-with-healthy- cagr-2027-2019-01-16

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During the water electrolysis process, an elec-trolyzer converts electricity and water into gaseous hydrogen and oxygen, which can be stored for later use as an energy source. Unlike most hydrogen production methods, water elec-trolysis doesn’t produce pollution or damaging greenhouse gases as by-products of the conver-sion process.

Historically speaking, large-scale systems that the water electrolysis process requires were considered costly and inefficient. But, techno-logical advances have improved the economic and commercial viability of water electrolysis systems. Many industry experts predict that future energy conversion and storage will use water electrolysis for hydrogen production.

Hydrogen via Water Electrolysis Supports Other Clean Energy Applications

Hydrogen generated by water electrolysis helps stabilize electrical grids when they rely solely on intermittent renewable sources like wind tur-bines and solar cells.

Renewables face a challenge of keeping energy production consistent and reliable, matching supply with demand. Solar power generation peaks at midday and ends at sunset—but, sometimes cloud cover interferes.

Because peak energy consumption generally occurs between mid-afternoon to early eve-ning—with variations based on region and sea-son—energy supply can drop, with little means to generate more. Hydrogen production, via electrolysis, can supplement these renewable energy gaps more sustainably.

Fuel cells—which use hydrogen and oxygen to produce electricity—can also compensate for times of lower energy production from renewables. Utility and grid operators can use commercial-scale systems to convert and store excess renewable power as hydrogen to supple-ment higher demand. Water electrolysis and oth-er clean energy applications can work in parallel to support a sustainable hydrogen economy.

Water Electrolysis as a Means for Clean and Green Hydrogen Production

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Hydrogen Production Provides Versatile Solutions to Downstream Industries

⁴Source: https://www.grandviewresearch.com/industry-analysis/hydrogen-generation-market

Hydrogen production and storage can be used for more than just renewable energy generation, branching out and benefiting other markets, such as the transportation, agriculture, and manufacturing industries that also need energy.

Automobile Fuel Cells

Unlike conventional vehicles that run on gasoline or diesel, fuel cell cars combine hydrogen and oxygen to produce electricity that runs their motors. Classified as electric vehicles (EVs) because they’re powered entirely by electricity, the range and re-fueling processes of fuel cell vehicles compare favorably to conventional cars and trucks.

Ammonia Production

The expanding ammonia production market relies heavily on hydrogen. The agriculture indus-try needs hydrogen to produce ammonia, a basic ingredient in most fertilizers.⁴ When added to high-moisture grains, ammonia controls mold growth. It adds non-protein nitrogen to corn silage— the stored, fermented, high-moisture fodder fed to cattle, sheep, and other cud-chewing livestock. Hydrogen used in ammonia production also yields by-products used in pharmaceuticals and plastics.

Hydrodesulfurization of Petroleum Products

Hydrogen is used to hydrodesulfurize fuels in the oil refining process. This catalytic chemical reaction reduces sulfur from petroleum products, including gasoline, kerosene, jet fuel, fuel oil, diesel, and natural gas.

All of these applications—as well as more sustainable technologies—stand to benefit from dependable, consistent access to hydrogen. This demand for carbon-free hydrogen drives innovation in the electrolysis process and membrane technology used to separate hydrogen from oxygen.

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Alkaline Electrolysis

In this process, the reaction occurs in a solution composed of water and potassium hydroxide (KOH) liquid electrolyte between two electrodes. When the two electrodes receive sufficient volt-age, the cathode water molecules take electrons to form OH (hydroxide) ions and H2 (hydrogen) molecules.

OH ions travel through the KOH electrolyte toward the anode, where they combine and re-lease extra electrons to make water and oxygen (O2). A diaphragm with micrometer-sized pores prevents hydrogen and oxygen from mixing.

Proton Exchange Membrane (PEM)

In this process, a PEM conducts protons from the anode to the cathode, while providing electrical insulation to the electrodes.

Negatively charged oxygen molecules give up electrons at the anode to make protons, elec-trons, and O2 when a potential difference (volt-age) is applied between the two electrodes.

H⁺ ions travel through the proton-conducting membrane towards the cathode, where they combine with the electrons to make H2. The PEM allows only the positively charged ions to pass through to the cathode.

Currently, there are two main types of systems commercially available: alkaline and proton exchange membrane (PEM) water electrolyzers. Both alkaline and PEM technologies can deliver on-site and on-demand hydrogen, as well as ultrapure, dry, and carbon-free hydrogen.

Differentiating Types of Water Electrolysis

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The Next Step Towards a Hydrogen Economy 77

Advantages of PEM

Proton exchange membrane (PEM) water electrolysis provides a better alternative when paired with intermittent power sources. While the historical high cost of PEM components limited the system’s use in large-scale commercial applications in the past, recent technology developments have shrunk costs considerably—making PEM components more feasible options in many new use cases.

Proton exchange membrane water electrolyzers offer several advantages that make them well suited for the demands of twenty-first century hydrogen production.

Proton exchange membranes can:

• Operate at high current density that results in reduced costs, especially for systems coupled with very dynamic energy sources—like wind and solar—where sudden spikes in energy input would otherwise result in uncaptured energy

• Work with a very thin membrane, even at high pressures, because of their polymer electrolyte

• Deliver higher energy efficiency because their proton membrane has lower ohmic losses

• Exhibit a low gas crossover rate, which yields very high product gas purity critical for storage safety and direct use in fuel cells

• Operate without corrosive chemicals

Proton exchange membranes can also be used in smaller systems because they operate at high power density. Alkaline water electrolysis can require up to ten times the footprint of PEM water electrolysis—an important consideration for customers with space restrictions.

Issues with Alkaline Membrane Electrolyzers

While systems that use alkaline membranes cost less, they have experienced performance issues in renewable energy applications.

Hydroxide support across the diaphragm inside alkaline electrolyzers responds slowly to power input, limiting the electrochemical reaction and leading to low current density. The diaphragm’s porous structure allows the diffusion and mix-ture of hydrogen and oxygen when operating at a low density, which limits its operational safety range.

Conventional electrodes used in alkaline elec-trolyzers tend to have low surface areas, poor catalyst utilization, and associated voltage losses. These issues lead to low power density and require larger systems to support these electrodes.

Choosing the Right Water Electrolyzer

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Technological advances and innovative mem-brane research have risen to meet the challenge of identifying and addressing evolving require-ments of PEM electrolyzers.

Chemours researchers continue to develop Nafion™ membranes, which are made from an ion exchange polymer. This perfluorinated polymer provides chemical and thermal stability.

Perfluorinated cation exchange sites attached to the perfluorinated polymer chains make the

Advances in Membrane Technology

polymer permeable to many cations and polar compounds. Cation and polar compound sizes and electrical properties determine their mo-bility through the polymer. The membrane can reject anions and non-polar species.

Proton exchange membrane electrolyzers use membranes like Nafion™ N115 and N117 because they offer high conductivity, reliability, and performance that current and future water electrolysis applications need.

Their physical reliability helps facilitate easier handling, resist operational upsets, and main-tain reliable performance over the membrane’s lifetime.

Chemours scientists in collaboration with part-ners are also designing the next generation of Nafion™ membranes and dispersions to operate in higher temperature ranges and lower humidi-ty. Hence, even in the most demanding operating conditions, you can count on the efficiency of our membranes and dispersions.

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The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. Chemours makes no warranties, express or implied, and assumes no liability in connection with any use of this information. Nothing herein is to be taken as a license to operate under or a recommendation to infringe any patents or trademarks.

©2019 The Chemours Company FC, LLC. Nafion™ and any associated logos are trademarks or copyrights of The Chemours Company FC, LLC. Chemours™ and the Chemours Logo are trademarks of The Chemours Company.

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Reinventing the Energy Market with Nafion™ Membranes

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With over 50 years of experience, the Nafion™ membranes and dispersions team has the knowledge to lead the energy industry on the journey toward a safer, cleaner world. Nafion™ ion exchange membranes have been the products of choice for chlor-alkali electrolysis, providing unparalleled performance and durability. Today, Nafion™ membranes also offer leading-edge solutions for energy storage, fuel cells, water electrolysis, ultra-high purity chemical production, and other specialty applications.

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