The 33rd China International Exhibition on Electric Power Equipment and Technology
Shanghai International Energy Storage Technology Application Expo / Hydrogen Energy Expo
Water electrolysis is the process of using an electric current to decompose water (H?O) into hydrogen (H?) and oxygen (O?) through electrochemical reactions at the anode and cathode of an electrolyser. When powered by renewable electricity, the hydrogen produced is termed 'green hydrogen' — the cleanest form of hydrogen production with near-zero lifecycle carbon emissions. The three main electrolyser technologies are Alkaline Electrolysis (AEL), the most commercially mature and lowest-cost option; Proton Exchange Membrane (PEM) electrolysis, offering faster response and higher purity hydrogen suitable for dynamic operation with variable renewable power; and Solid Oxide Electrolysis (SOEC), an emerging high-efficiency technology operating at elevated temperatures. China is the world's largest electrolyser market and manufacturer, with domestic companies rapidly scaling production capacity.
5 Key Questions About Water Electrolysis
Alkaline electrolysers (AEL) use a liquid potassium hydroxide electrolyte and nickel-based electrodes, offering low capital cost and long operational life — making them the dominant technology for large-scale industrial hydrogen production. PEM electrolysers use a solid polymer membrane and precious metal catalysts (platinum, iridium), enabling faster start-up, wider load range, and higher hydrogen purity, making them better suited for coupling with variable renewable energy sources. PEM systems have higher capital costs but are declining rapidly as manufacturing scales up. The choice between technologies depends on scale, power source variability, and purity requirements.
Producing one kilogram of hydrogen by water electrolysis requires approximately 50–55 kWh of electricity for current commercial systems, though advanced systems are approaching 45 kWh/kg. Since hydrogen has an energy content of approximately 33 kWh/kg (lower heating value), the round-trip efficiency of electrolysis is approximately 60–70%. The electricity cost is therefore the dominant factor in green hydrogen economics — at a power cost of USD 0.03/kWh, electricity alone accounts for approximately USD 1.50–1.65/kg of hydrogen, before capital and operating costs.
China has become the world's largest electrolyser market, with installed capacity growing from under 100 MW in 2020 to several gigawatts by 2024. Chinese manufacturers including PERIC, Sungrow Hydrogen, Longi Hydrogen, and CSSC Huahai have rapidly scaled alkaline electrolyser production, driving down costs significantly. The National Development and Reform Commission's hydrogen development plan targets 100,000–200,000 tonnes of green hydrogen production per year by 2025, requiring several gigawatts of electrolyser capacity.
Electrolysers can be coupled directly with wind or solar farms to convert surplus renewable electricity into hydrogen, providing a productive use for generation that would otherwise be curtailed. This 'power-to-hydrogen' pathway helps solve the intermittency challenge of renewables by storing energy in chemical form. PEM electrolysers are particularly well-suited for this application due to their ability to ramp up and down rapidly in response to variable power input. Grid-connected electrolysers can also provide demand response services, reducing consumption during peak periods and increasing it when renewable generation is abundant.
Green hydrogen produced by water electrolysis has applications across multiple sectors: industrial feedstock (replacing grey hydrogen in ammonia synthesis, refining, and chemical production), transportation fuel (for fuel cell vehicles, buses, trucks, trains, and ships), power generation (via hydrogen turbines or fuel cells for grid balancing), heating (blending with natural gas or direct combustion in industrial processes), and long-duration energy storage. The decarbonisation of hard-to-abate industrial sectors — steel, cement, chemicals — is considered the highest-value application for green hydrogen given the limited alternatives.
Key Takeaways
Water electrolysis is the foundational technology for green hydrogen production, converting renewable electricity into storable, transportable clean fuel. China's rapid scale-up of electrolyser manufacturing is driving down costs and positioning the country as a global leader in the hydrogen economy. HE Shanghai, co-located with EP Shanghai, is Asia's premier platform connecting electrolyser manufacturers, system integrators, and hydrogen project developers with buyers and partners.
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