Development Trend of International Hydrogen Production Technology from Electrolytic Water

From the development history, alkaline water electrolysis began to realize the industrial application of alkaline water electrolysis hydrogen production technology around the 20th century. After the development process of unipolar to bipolar, small to large, atmospheric to pressurized, manual control to full automatic control, alkaline water electrolysis hydrogen production technology has gradually entered a mature stage of industrial application. Since the 1970s, proton exchange membrane water electrolysis hydrogen production technology has begun to develop, and has become the research focus of water electrolysis technology due to its high hydrogen production efficiency, high degree of equipment integration and environmental friendliness, gradually realizing the development from miniaturization to megawatt level.

At present, the bottleneck of PEME hydrogen production technology is that the equipment cost is high, the service life is low, and the actual electrolysis efficiency is far lower than the theoretical efficiency (its hydrogen production efficiency potential is expected to exceed AE hydrogen production technology). Therefore, developed countries in Europe and the United States are focusing on technological breakthrough to break through the technical bottleneck and achieve greater development of PEME hydrogen production technology. SOE hydrogen production technology uses steam electrolysis, which works under high temperature environment, with the highest theoretical energy efficiency, but this technology is still in the laboratory research and development stage.

At present, the United States, Japan, South Korea and Europe all regard electrolytic water hydrogen production technology as the mainstream development direction in the future, focusing on the scale of AE hydrogen production technology and the industrialization of PEME hydrogen production technology, and focusing on the three key cost reduction performance indicators of "electrolytic efficiency", "durability" and "equipment cost" to promote the overall technology research and development. The cost structure and key technology analysis of electrolytic water hydrogen production are shown in Figure 1.

Figure 1 Cost Structure and Key Technology Analysis of Hydrogen Production by Electrolytic Water

In 2011, the United States developed a technical roadmap for hydrogen production from electrolytic water, as shown in Figure 2. With the goal of 2.3 dollars/kg of hydrogen production cost, it set the development goals of system electrolytic efficiency greater than or equal to 75%, electrolytic cell electrolytic efficiency greater than or equal to 77%, and system investment cost of 0.5 $/kg.

In terms of technical route, PEME technology is mainly used to tackle key problems, and AE, SOE and other electrolytic water technologies are developed in parallel. In terms of technology development, PEME hydrogen production technology specifically focuses on the research of key core materials such as proton exchange membrane and precious metal catalyst to obtain higher electrolysis efficiency and life; At the same time, the research and development of low load nano precious metal catalysts and non precious metal catalysts, AE hydrogen production technology, the development of high-temperature alkaline water electrolysis device and the research of high efficiency were carried out.

Figure 2 Key Indicators and Objectives of Electrolytic Water Hydrogen Production Technology in the United States

In 2013, Europe formulated the technical route of hydrogen production from electrolytic water, which also focuses on PEME technology and coordinated development of various electrolytic technologies. The key technical indicators are shown in Figure 3. Among them, the technical target in 2023 is: electrolysis energy consumption ≤ 50 (kWh)/ kgH2@1000kg /d. The annual reduction of electrolytic cell efficiency is less than 1% (annual operation time under rated power is 8000h), and the equipment investment cost is less than 1.5M/(t/d).

In terms of PEME technology, Europe, on the one hand, improves the electrolysis efficiency through the research and development of key basic materials such as catalysts and electrolyte membranes, focuses on MW level system design, and reduces equipment investment costs; On the other hand, the performance evaluation and degradation evaluation system of PEME technology is established to scientifically evaluate the systematic economic effectiveness of technology. In terms of AE hydrogen production, Europe has developed a high temperature and high pressure compatible alkaline water electrolysis device, and further improved the hydrogen production efficiency by optimizing the peripheral equipment and operating conditions.

Figure 3 Key Indicators and Objectives of EU Electrolytic Water Hydrogen Production Technology

From 2014 to 2018, Japan made great efforts to promote the development of alkaline electrolyzed water devices, especially 2000Nm3/h large-scale electrolytic cell technology, through pioneering research and development projects such as hydrogen utilization and technology research and development projects for building a hydrogen society. In 2019, by benchmarking the development route of electrolytic water technology in the United States and Europe, Japan formulated a 10-year technical breakthrough goal for AE and PEME water electrolysis technology, focused on the research on reactor reaction mechanism, durability evaluation methods and standardization, and carried out system level optimization based on various information such as renewable energy generation forecast, power supply and demand adjustment, and hydrogen demand to improve current density, efficiency and durability, The objectives of relevant technical key indicators are shown in Figure 4 and Figure 5.

In general, all countries carry out technical development on AE and PEME hydrogen production technologies at the same time. In terms of AE, in the near future, the main goal is to optimize and improve the hydrogen production efficiency and scale up the unit.

In terms of PEME, European and American countries continue to carry out technical breakthroughs, and regard it as the next generation mainstream hydrogen production technology by electrolysis of water. Through the research and application of core materials and components such as catalysts, diaphragms, collectors, membrane modules, etc., the electrolysis efficiency and service life of equipment are improved, and the cost of equipment is reduced.

At the same time, Europe has carried out research on performance evaluation and degradation evaluation of hydrogen production equipment from electrolytic water, which is of great significance in the development of hydrogen production technology from electrolytic water. On the basis of absorbing the technical route of electrolyzed water hydrogen production in the United States and Europe, Japan has focused on the technical development of AE and PEME, and formulated the most comprehensive technical objectives.

Figure 4 Technical Objectives of Alkaline Electrolytic Water Hydrogen Production in Japan