Green Hydrogen’s Water Problem

US President Joe Biden’s green hydrogen plans have unexpectedly run into issues like they’re Mark Watney stuck on Mars: a water shortage.

Background: Green hydrogen uses electrolysis, a process that takes electricity and splits water into hydrogen and oxygen. Beyond using enough water to rival Aquaman, green hydrogen needs a special type of water known as ultrapure water for the electrolysis.

• For context on ultrapure water, Aquafina uses both advanced filtering and reverse osmosis to achieve ~2 parts per million of total dissolved solids (TDS) for its bottled water. The ultrapure water used for green hydrogen has a TDS of just 50 parts per billion or ~40 times purer.

Depending on how much de-mineralization is needed to make the ultrapure water, each kilogram of green hydrogen needs between 18 and 24 kilograms of water.

The details: Research by Food and Water Watch estimates the United States would require one trillion gallons of water per year to meet the Department of Energy’s 2050 green hydrogen goals.

• While ‘one trillion gallons’ sounds like a lot, it’s roughly 1 percent of the country’s current freshwater use.

The bigger issue: Many of the best places to generate renewable energy are the worst for water. According to Reuters, nine of the 33 green hydrogen hubs in the US that have been shortlisted for approval are in water-stressed regions.

Texas energy hub Corpus Christi would need millions of gallons of water for its hydrogen hubs but is currently facing a multi-year drought. The projects could install very expensive desalination plants to use seawater, but the proposed plants are being protested by environmental groups for threatening water ecosystems.

• “It makes no sense to create a purported clean energy source that in turn destroys an entire ecosystem, threatens other economies reliant upon a healthy bay system, and usurps the water supply for residents,” wrote the Coastal Alliance to Protect the Environment.

Zoom out: There is no such thing as a free lunch when it comes to decarbonization. Deserts are often the best place for cheap and abundant solar power, but the worst for the water needed to make green hydrogen.