Hydrogen production by water electrolysis (or water electrolysis for hydrogen production) is a method of hydrogen production that involves the decomposition of water into hydrogen and oxygen by electrolysis of water. This technology has significant advantages and disadvantages, and the following are the key advantages and limitations of hydroelectric hydrogen production:
Advantages
Highly environmentally friendly
The main by-product of the water electrolysis process is oxygen, which does not release greenhouse gases such as carbon dioxide, making it a clean and environmentally friendly way to produce hydrogen. It has a lower environmental impact especially when renewable energy sources (e.g. solar, wind) are used.
Easy availability of raw materials
Water is abundant as the main raw material, and electrolysis can be carried out by adding just the right amount of electrical energy. In contrast to hydrogen production from fossil fuels, hydrogen production from water electrolysis does not rely on limited natural resources.
High purity of hydrogen
Hydrogen generated from water electrolysis is usually of high purity, making it suitable for applications that require high purity hydrogen, such as fuel cells, aerospace and fine chemicals.
High compatibility with renewable energy sources
Hydrogen from water electrolysis can be combined with renewable energy sources, such as solar and wind, to produce hydrogen for storage using excess power from the grid, acting as an ‘energy store’ and improving the flexibility and stability of the grid.
Flexibility of application
Water electrolysis hydrogen production systems can be scaled to suit different needs, from small-scale decentralised applications to large-scale hydrogen production facilities.
A key technology for the low-carbon energy transition
Hydrogen production from hydropower is seen as an important way to realise a low-carbon energy system. As a clean energy carrier, hydrogen can be used in a variety of sectors such as industry, transport and power, providing important support for the low-carbon transition.
Disadvantages
Higher energy consumption
The water electrolysis process has a high demand for electricity, which is typically 60-80 per cent efficient, and requires a large amount of electricity to produce enough hydrogen. Hydrogen production from water electrolysis is costly and indirectly leads to carbon emissions, especially when fossil fuels dominate power generation.
Higher production costs
Hydrogen production from hydropower is currently much more expensive than other hydrogen production technologies (e.g. natural gas reforming) due to high energy consumption and expensive materials such as catalysts. The cost of hydropower hydrogen production is expected to decrease as production scales up and materials technology advances.
High requirements for electrolyser materials
Materials for the electrolyser (e.g., proton exchange membrane, electrodes, and catalysts) need to be corrosion-resistant, electrically conductive, and long-lived, resulting in high material and manufacturing costs, especially for precious metal catalysts, such as platinum and iridium, used in proton exchange membrane electrolysers (PEMs), which further push up the cost of the system.
Efficiency constraints
The efficiency of water electrolysis is limited by electrolyser materials and system design, making it more difficult to achieve 100% conversion efficiency. Therefore, there is still a need to improve electrolyser design and electrocatalyst technology to enhance overall efficiency.
Dependence on electricity supply
Hydrogen production by water electrolysis consumes a large amount of electricity, and the efficiency of hydrogen production is affected by unstable or costly electricity supply. Especially in areas with a low share of renewable energy, the economic and environmental benefits of hydrogen production from water electrolysis are limited.
Complicated equipment maintenance
Water electrolysis hydrogen production involves high temperatures, high pressures and highly corrosive environments (especially in PEM systems), requiring frequent maintenance and highly durable equipment, which increases operation and maintenance costs and technical difficulties.
Future Prospects
Despite the current limitations, the efficiency and cost of hydrogen production from water electrolysis is gradually improving with technological advances and scale-up. In addition, the global trend of transitioning to low-carbon energy sources and the popularity of renewable energy sources make water electrolysis hydrogen production a viable pathway for hydrogen production with a broad application prospect.