Electrolysis

Using electric current to drive a chemical reaction, most prominently splitting water into hydrogen and oxygen.

• Current between two electrodes in water releases hydrogen at one and oxygen at the other, while a membrane keeps the gases apart.
• It takes about 50–55 kWh of electricity to make 1 kg of hydrogen, against a theoretical minimum near 39 kWh.
• Green hydrogen could replace fossil hydrogen in fertiliser, refining and steel, where electricity alone can't do the chemistry.
• At roughly $4–6/kg versus about $1–2 for hydrogen from natural gas, it depends on cheap power, high utilisation and subsidies.