Electrolysers are at the heart of green hydrogen production. They are the devices that make it possible to split water into hydrogen and oxygen using electricity — a process called electrolysis. When this electricity comes from renewable sources like solar or wind, the hydrogen produced is completely clean and emission-free.

How Electrolysers Work

The basic idea behind all electrolysers is the same. Water (H₂O) is fed into the system and exposed to an electric current. This current separates the water molecules into hydrogen (H₂) and oxygen (O₂). The hydrogen is collected and stored as fuel, while oxygen is released into the atmosphere.

An electrolyser consists of two electrodes — an anode and a cathode — separated by an electrolyte. When electricity passes through the water, hydrogen forms at the cathode, and oxygen forms at the anode. Though the principle is simple, the technology that enables it efficiently and reliably is sophisticated and constantly evolving.

Types of Electrolysers

There are three main types of electrolysers used today, each with its own strengths and ideal applications:

1. Alkaline Electrolysers (AEL)
The most established technology, alkaline electrolysers use a liquid electrolyte (usually potassium hydroxide). They are reliable, cost-effective, and suited for large-scale hydrogen production. However, they have slower response times and are less flexible when paired with variable renewable power sources.

2. Proton Exchange Membrane (PEM) Electrolysers
PEM electrolysers use a solid polymer membrane as the electrolyte. They operate at higher current densities, have faster response times, and are compact in design. These qualities make them ideal for integration with solar or wind power, where electricity supply fluctuates. Their main drawback today is higher cost due to the use of precious metals like platinum in their construction.

3. Solid Oxide Electrolysers (SOEC)
These electrolysers operate at very high temperatures (around 700–1,000°C) and use a ceramic electrolyte. The heat allows for higher efficiency, especially when combined with industrial processes that already produce waste heat. However, the technology is still developing and less commercially mature than AEL or PEM systems.

The Future of Electrolyser Technology

Advancements in materials, efficiency, and scale are rapidly improving electrolyser performance. Global manufacturers are building gigawatt-scale factories to reduce costs through mass production. Research is also underway to develop anion exchange membrane (AEM) electrolysers — a hybrid design that combines the best features of alkaline and PEM systems while lowering material costs.

As electrolyser technology improves, it will play a crucial role in making green hydrogen affordable and widely available. These machines are not just tools for producing fuel — they’re the engines driving the transition to a cleaner, more sustainable energy future.