Comprehensive analysis of the four major electrolyzed water technologies and development trends in Europe and the United States

With the gradual development of my country's top-level policy system for hydrogen energy, hydrogen energy is expected to be officially incorporated into the national energy system in the near future. At the same time, fuel cell and FCV technologies are becoming more and more mature. The source and cost of hydrogen have become one of the key factors restricting the development of the industry, and electrolyzers have also become a hot spot in the industry. This article has sorted out the four major water electrolysis technologies and the development trends in Europe and the United States, which are alkaline (ALK), anion exchange membrane (AEM), proton exchange membrane (PEM) and solid oxide (SOEC).

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1. Introduction

In terms of materials, performance, efficiency and cost, the four water electrolysis technologies in the above figure have their own advantages and challenges. Compared with alkaline electrolyzers, the advantages of PEM in specific application scenarios (such as vehicle-grade hydrogen energy and variable renewable energy) are becoming more and more obvious. Many new projects in the world have begun to use PEM electrolyzers, and its market penetration rate is expected to increase. gradually expand. As emerging technologies, SOEC and AEM have great potential and are also the focus of research and development in Europe and the United States. However, the former needs to be improved in terms of durability and manufacturing process before mass production, and the latter is still in the research and development stage of basic materials.

The Technology Readiness Levels (TRLs) listed in the chart above are DOE 2020 classifications. The EU's assessment of its SOEC in 2020 is TRL7, which is higher than the US Department of Energy's TRL5-6.

Both the United States and the European Union take PEM and SOEC electrolysis of water as their near-term research and development priorities, and biomass (Biomass) hydrogen production as a medium-term goal. In addition, the U.S. Department of Energy takes direct use of the sun’s light and heat (photoelectric catalysis) to produce hydrogen as a long-term R&D strategy, and its three major hydrogen production routes are specifically reflected in the maturity of each related technology in Figure 2 below.

2. Proton exchange membrane electrolyzer

Proton exchange membrane (PEM) electrolyzers use thinner perfluorosulfonic acid membranes (PFSA) and advanced electrode structures for low resistance and high efficiency. PFSA membranes are chemically, mechanically stable and pressure resistant, so PEM cells can operate at up to 70 bar while the oxygen side is at atmospheric pressure. The disadvantage of PEM electrolyzers is that they need to work in highly acidic, high potential and unfavorable oxidizing environments, thus requiring highly stable materials. Expensive titanium-based materials, noble metal catalysts, and protective coatings are necessary, which not only provide high stability for battery elements, but also good conductivity and battery efficiency. PEM systems have a compact, simple design, but are sensitive to water impurities (eg iron, copper, chromium, sodium) and can be affected by calcination.

The above table shows the major suppliers of PEM electrolysis water systems in Europe and the United States, which have had major financing, mergers and acquisitions and integrations in recent years. For example, UK ITM completed a £172 million financing in 2020 (including 30 million from Italian Snam), following a £58.8 million financing in 2019 (including 38 million from Linde), and plans to build one in 2023 and 2024 respectively. Plants with an annual capacity of 1.5GW and 2.5GW.

In continental Europe, in October 2020 the French Gaztransport & Technigaz (GTT Group) acquired AREVAH H2Gen for around €8 million and renamed it Elogen. As the world's top liquefied natural gas (LNG) membrane patent technology provider, GTT is the patent owner of the membrane-type LNG carrier cargo hold containment system, and its various membrane-type technologies are widely used by shipowners and shipyards around the world. It is worth mentioning here that in the storage and transportation of thin-film liquid hydrogen (LH2) at the next strategic commanding height, Zhongtai Marine Technology (Shanghai) Co., Ltd. built the world's first thin-film liquid hydrogen storage and transportation simulation cabin in Wuxi in September 2021. , has achieved a major breakthrough in liquid hydrogen storage and transportation technology and engineering applications, laid a good foundation for future related technologies to be put into marine use, and further consolidated China's leading position in the international track of hydrogen energy storage and transportation technology.

In the US, Plug Power acquired Giner ELX for $58 million in 2020 and Frames Group for $98 million last year, giving it the former's PEM water electrolysis laboratory technology and the latter's equipment and engineering capabilities. In addition, Plug acquired United Hydrogen, a civilian liquid hydrogen production, storage and transportation company, for $65 million in 2020. After fuel cell forklifts, Plug plans to develop PEM water electrolysis into its other main business. In 2007, Plug acquired General Hydrogen, which focused on forklift business (the company was founded by Geoffrey Ballard after leaving Ballard in 2000), for $10 million, and started the ice-breaking journey of fuel cells in the forklift field; More than 40,000 forklifts have been deployed.

As a representative of the US electrolyzed water technology, Giner ELX and its original parent company Giner Labs have several PEM and AEM R&D projects funded by the US Department of Energy. At present, the research and development of PEM water electrolysis materials in the United States focuses on mechanism research and improvement of material properties, while AEM focuses on material development and mechanism research, and has established a research and development project led by universities and national laboratories as shown in the figure below.

3. Anion exchange membrane electrolyzer

As the latest water electrolysis technology, the potential of anion exchange membrane (AEM) electrolyzers lies in combining the low cost of alkaline electrolyzers with the simplicity and efficiency of PEM. The technology can use non-precious metal catalysts, titanium-free components, and can operate under differential pressure like PEM, but the current AEM membrane has problems with chemical and mechanical stability, which affect the life curve. In addition, the low conductivity, slow catalytic kinetics, and poor electrode structure of AEM membranes also affect the performance of AEM. Improvements in performance are usually achieved by tuning the conductivity of the membrane, or by adding supporting electrolytes (eg, KOH, NaHCO3), which in turn reduce durability. In PEM, the conduction velocity of OH- ions is three times slower than that of H+ protons, so AEM will face greater challenges, requiring the development of thinner or higher charge density membranes. requirements.

According to whether alkaline electrolyte is needed, the current research and development direction of AEM in the world is divided into alkaline electrolyte system and pure water system (ie, no lye solution, which is convenient for system maintenance). The former is R&D focused on improving current density and durability; the latter is improving membrane stability and using advanced membranes and PGM-free (or low) catalysts to improve performance and durability. In addition, the unit stack cost of AEM is much lower than that of PEM, so it is also a research and development strategy to improve the power efficiency of AEM by reducing the cell voltage.

AEM technology is still in the research and development stage. The leading international developer and manufacturer is ENAPTER in Italy, which has realized the commercialization of small-scale products. The upper right of the figure below discloses the parameters of its products, and the lower right is the questionnaire survey information of the US Department of Energy in 2021.

The current research and development focus of ENAPTER is to improve the conductivity and durability of membranes in pure water systems, in order to achieve current density >1A/cm2 (cell working voltage 1.8V) and decay rateAs the birthplace of modern PEM fuel cell technology, Canada has a number of forward-looking technology companies such as Ballard, Hydrogenics, Carbon Engineering, Westport, etc., which benefits from the Canadian government's high emphasis on breakthrough innovation. In 1983, a company then called Ballard Research Inc. received a $500,000 grant from the Canadian federal government to begin the commercialization of PEM fuel cell technology. Today, the industry hopes that Ballard's history can be repeated at Ionomr. The picture below shows Dominic Barton, the then Canadian ambassador to China and former global president of McKinsey, visiting the company's booth and Canadian exhibition area at FCVC 2021.

4. Solid oxide electrolytic cell

Solid oxide (SOEC) cells operate at high temperatures (700-850°C), and the kinetic advantages allow the use of inexpensive nickel electrodes. If using high-quality waste heat in industrial production (for example, the energy input is 75% electrical energy + 25% thermal energy in water vapor), the system efficiency of SOEC (LHV H2 to AC) is expected to reach 85% in the near future, and reach the EU within 10 years. 90% of the 2030 target. The SOEC electrolyzer feeds water vapor, and if carbon dioxide is added, it can generate syngas (Syngas, a mixture of hydrogen and carbon monoxide), and then further produce synthetic fuels (e-fuels, such as diesel, jet fuel). Therefore, SOEC technology is expected to be widely used in carbon dioxide recovery, fuel production and chemical synthesis, which is the focus of research and development in the EU in recent years. Another advantage of SOEC is reversibility, that is, the use of reversible fuel cells for the storage of renewable energy, which is also a long-term key research and development topic in Europe and the United States.

Durability is the primary issue of SOEC at present. Thermochemical cycles, especially when the system is stopped and started, will accelerate aging and reduce service life. Current solid oxide materials include zirconium dioxide, which is stabilized by adding 8% yttrium oxide, and has the formula (ZrO2)0.92(Y2O3)0.08. Improving the performance, durability and lowering operating temperature of solid oxides is currently the focus of research and development in Europe and the United States.

US SOEC representative companies include FuelCell Energy and Cummins. During 2016-2020, FuelCell Energy led a SOEC R&D project with a US Department of Energy grant of $3 million and achieved the metrics below.

- Stack efficiency (LHV H2 to AC)>95%

- System efficiency (LHV H2 to AC)>90%

- System Efficiency (LHV, calculated as electrical energy + thermal energy)>75%

- Single cell decay rate ≤1%/1000 hours; stack decay rate ≤2%/1000 hours

- Develop subsystems to make SOEC compatible with intermittent renewable energy sources

In September 2021, Cummins received a $5 million grant from the U.S. Department of Energy for the research and development of automated assembly and production of SOEC stacks. The project will leverage Cummins' existing proven thermal spray process to automate the production of metal-based solid oxide stacks, thereby reducing the costly sintering process and reducing the number of seals required by 50 percent. The three-year project, with a total budget of $7.16 million, aims to develop a standard prototype for automated assembly of 60kW solid oxide stacks for the establishment of a SOEC electrolyzer plant with an annual capacity of 94MW.

In January 2020, the EU launched the SOEC demonstration project with a total budget of 9.75 million euros (of which FCH JU contributed 7 million), aiming to improve the technical maturity of SOEC from TRL7 to TRL8 within five years, and formulated the following KPIs.

- System power consumption (standard working condition) ≤ 39kW/kgH2

- stack decay rate ≤ 1.2%/1000 hours- Operating time ≥ 98 %

- Unit investment cost (1 kg of hydrogen per day) ≤ EUR 2,400

- Annual operating and maintenance costs (1 kg of hydrogen per day) ≤ 120 euros

German Sunfire is the European SOEC technical representative. The Saxony-based company was founded in 2010 and acquired a SOFC company the following year as the technological core of its later development. Based on a Power-to-Liquid (PtL) process, Sunfire built a 2.4MW SOEC project demonstration in the Netherlands in October 2020, producing 60 kg of hydrogen per hour for synthetic fuel production, and its system electrical energy efficiency (LHV H2 to AC) target is 85%.content_copyshare

Sunfire is an active participant in the German H2Giga program. Earlier this month the company and 15 partners it leads received 33 million euros in funding from the German Federal Ministry of Education and Research (BMBF) for SOEC electrolyser system optimization, manufacturing processes and mass production.

Sunfire secured a €109 million Series D round in November 2021 (it had previously raised more than €100 million) and plans to build a 200MW SOEC electrolyser capacity in 2023. On the M&A front, Sunfire acquired the Swiss electrolyzer company IHT in January 2021 and installed the EU's first 3.2MW alkaline electrolyzer with a working pressure of 30 bar in a food production center in Austria in November. The electrolyser is a central part of the EU's Demo4Grid demonstration project to demonstrate the commercial viability of a pressurized alkaline electrolyzer to balance the grid and produce green hydrogen for industrial use under real market conditions. The five-year project has a total budget of EUR 7.8 million, including EUR 2.9 million from the FCH JU.

The figure below shows the EU's 2010-2021 period of the application of fuel cell technology in the energy field, demonstration projects (such as cogeneration, balancing grid, off-grid power generation) funding, which has been used for PEMFC, SOFC and other technologies every year since 2018. Project funding is approximately 78 million, 70 million and 8 million euros (blue, orange, green legends). Major participating companies and research institutes include: SolidPower, Sunfire, Ballard, Politecnico di Torino (Polytechnic University of Turin) and VTT Technical Research Centre of Finland.

5. U.S. hydrogen energy R&D system

Stones from other hills, can learn. This section takes the research and development of electrolyzed water as an example to introduce the research and development system in the United States, which is divided by technology maturity and led by national laboratories. Hereinafter RD&D = Research, Development & Demonstration.

The Technology Readiness Level (RTL) evaluation method has been used by the aerospace and defense departments in the United States for a long time. and configure the corresponding resources. This tool proved to be very effective and feasible, not only to assess the needs of different stages of development, but also to provide the necessary guidance for the final product.

The U.S. Department of Energy (DOE) is the administrative department of the U.S. federal government responsible for energy policy formulation, industry management, and related technology research and development. Among its 17 national laboratories, 14 are currently engaged in hydrogen energy-related research and development. DOE divides electrolyzed water research and development topics into three categories according to the technological maturity, and forms a corresponding consortium, so as to form a three-level gradual process from basic materials, key components to production and manufacturing, and avoid weak key components in the demonstration and promotion stage. situation. In addition, DOE's funding is not limited to local units in the United States. For example, Ballard in Canada has obtained tens of millions of dollars in research and development funds from DOE in the form of various contracts.

Basic materials are the cornerstone of high-end manufacturing. As far as hydrogen energy is concerned, the U.S. Department of Energy has established a hydrogen energy materials research and development network composed of the following four material alliances to accelerate the breakthrough of early application materials in the field of hydrogen energy.

6. Retrospect and Prospect

Since the invention of electrolyzed water in the UK in 1800, the development of electrolyzers has gone through more than two centuries, and technological advances (especially breakthroughs in materials) in different periods have greatly influenced its development process. Before 1950, electrolysis of water was mainly used to produce synthetic ammonia from low-cost hydropower, and alkaline electrolyzers were the only technology in this period. In the 1940s, DuPont invented a material with both mechanical, thermal stability and good proton transport properties, which made PEM technology possible, and was first used in aviation and military fields, and entered the commercial field in the 1980s. After 2010, with the promotion of photovoltaic and wind power and the reduction of the cost of electrolyzers, green hydrogen has become a commercially viable case, and has entered the energy policy agenda of various countries with the global consensus on climate action.

In the next five years, the author expects that PEM electrolyzed water will go from niche to mainstream, and achieve a leap from MW to GW. With the continuous breakthrough of material technology, SOEC is expected to usher in a substantial development stage, and AEM has also begun to gradually enter the early market. In addition, the investment in new hydrogen production research and development in various countries will continue to increase, which may usher in the emergence of disruptive technologies, such as biology and sunlight water molecule cracking technology.

Looking back on history, the development of space technology has also greatly advanced the frontier of fuel cell research and development. In the 1990s, NASA developed a research and development plan for the Unitized Regenerative Fuel Cell System (Unitized Regenerative Fuel Cell System) for its outer space program, and in the early 2000s, Proton OnSite developed a PEM system. technology-based reversible fuel cells. In addition, Bloom Energy's commercialized ES-5000 energy server is also derived from its solid oxide technology developed for NASA's Mars program.

The blue thread on the road leads to the opening of the mountains and forests. The internationally renowned Dalian Institute of Chemical Physics is the birthplace of my country's fuel cell technology. Its initial research originated from the task of developing aerospace hydrogen-oxygen fuel cells in 1967. Today, half a century later, following the successful completion of the Mars exploration mission in 2021, the National Space Administration plans to conduct the first manned Mars exploration in 2033 to explore the establishment of permanent settlements on the red planet, so that humans can live on Earth in the vast universe. Watch each other on Mars.

Conclusion: The competition for the first place depends on the continuous flow; the development of hydrogen energy depends on the continuous breakthrough of technology. At this historic moment when hydrogen energy and FCV converge and develop, understanding the latest developments at home and abroad and grasping the correct technical direction will become the key to corporate planning and decision-making. Travel far and far, never give up!

Source: Electrolyzed Water Technology Channel

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