Green hydrogen runs on ultrapure water

On 7 May 2026 the European Commission announced the results of the third European Hydrogen Bank auction: about 1.09 billion euro for nine projects in Austria, Denmark, Finland, Germany, Greece, Norway and Spain, with around 1.1 GW of electrolyser capacity expected to produce more than 1.3 million tonnes of renewable hydrogen over ten years.

Electrolysis splits water, so each kilogram of hydrogen consumes roughly nine litres of water as feed, before cooling and losses. That water has to be far purer than drinking water. Many PEM electrolyser makers specify a conductivity below 0.1 microsiemens per centimetre, with limits on silica and organics, because dissolved ions foul and scale the cell stack and shorten its life.

The usual treatment train is pretreatment, two-pass reverse osmosis, membrane degassing to remove carbon dioxide, and electrodeionisation, with a mixed-bed ion exchange polisher as a safeguard. EDI runs at around 95 percent recovery and its concentrate can be returned to the RO inlet, which keeps the overall water footprint low.

Theway Membranes supplies the RO elements and UF modules for pretreatment, and Davey Products designs and builds complete RO plants. For developers and research teams testing new electrolyser membranes, Tech Inc builds the casting, spinning and test equipment. VDT Europa delivers all three in the EU.

Supplied in Europe

In the European Union, Davey Group equipment is supplied, contracted and supported by VDT Europa OÜ in Tallinn, Estonia. Contact contact@vdteuropa.com.

Sources: European Commission, results of the third European Hydrogen Bank auction (7 May 2026); industry guidance on ultrapure water for PEM electrolysis.