Alkaline Water Electrolysis (AWE)

In plain terms

An alkaline electrolyzer passes direct current through cells that hold a liquid potassium hydroxide (KOH) solution. Hydrogen forms at the cathode, oxygen at the anode, and a porous diaphragm keeps the two gases apart. Electrodes are nickel-based, so AWE needs no platinum-group metals.

Stacks are built either near atmospheric pressure or pressurised, which changes how much compression the plant needs downstream. AWE is widely used for large, steady plants. Its weakness is speed: the Clean Hydrogen JU puts state-of-the-art hot-idle ramp time at 60 s and cold start at 3,600 s, against 2 s and 30 s for PEM (2020 baseline, SRIA 2022).

Typical range

System electricity use is 50–55 kWh/kg H₂ at today's state of the art: 50 kWh/kg per the Clean Hydrogen JU (2020 baseline, system boundary, cooling included) and 55 kWh/kg per the US DOE (2022 status). Targets are 48 kWh/kg by 2030 (Clean Hydrogen JU) and 52 kWh/kg by 2026 (DOE).

Why it moves LCOH

Low stack cost is AWE's main advantage: DOE puts uninstalled system cost at $500/kW (2022 status), half the $1,000/kW it gives for PEM. That advantage holds only when the stack runs many hours. On a variable solar or wind supply, the minimum load and slow ramps cut usable hours and push up cost per kilogram. Sebbahi et al. (2026) studied this coupling for a 20 kW alkaline electrolyzer fed by solar and wind at Moroccan sites.

Common mistake