Water Impacts in Hydrogen Production Must be Considered

Hydrogen has emerged as clean energy source that could help to decarbonize the “hard-to-abate” industrial, aviation, and long-distance transportation sectors.

The federal government has funded a number of programs to rapidly improve clean hydrogen production technology in order to meet the U.S. goal of net-zero carbon emissions by 2050. Programs to develop hydrogen technology include the Hydrogen Shot effort to bring down the cost of clean hydrogen by 80%, to $1 per kilogram in one decade.  

The Regional Clean Hydrogen Hub program will provide $7 billion in federal funding to create networks of hydrogen producers, consumers, and local connective infrastructure to accelerate the use of hydrogen. The Department of Energy is working with seven selected projects around the country, including the ARCH2 project in the Applachian region.

Hydrogen emits only water vapor when burned, and is produced in a number of ways. Gray hydrogen is produced with natural gas using steam reformation, but is not clean because carbon dioxide emissions result. When that process is coupled with carbon capture and sequestration to store the CO2, the resulting hydrogen is known as “blue” hydrogen. “Green” hydrogen is produced by splitting water molecules using several methods using renewable energy.

But all hydrogen production technologies require large amounts of water as an input, not only for production but also for cooling, as high heat results. A recent report by the International Renewable Energy Agency (IRENA) studied the water withdrawal and consumption requirements of various methods and compared them.

The report found that about 2.2 billion cubic meters of freshwater is withdrawn for hydrogen production around the world every year, accounting for .6% of the energy sector’s water use. That amount equals roughly 581 billion gallons of water. That amount could more than triple by 2040 and increase six-fold by 2050, IRENA projected.

The report determined that green hydrogen is the most water efficient of all types of clean hydrogen production, followed by blue hydrogen production. Coal gasification, where coal is broken down using a heat and chemical process to produce hydrogen and CO2, is by far the most water intensive, and becomes about 60% more intensive when CCS is used to make the hydrogen clean. The report noted that one such plant producing 237 kilotons of hydrogen would be equal to half the water demand in London for a year.

IRENA also noted that when planning for hydrogen projects, local water availability would have to be considered, especially in water-stressed regions. Some 35% of green and blue hydrogen production in operation and planned across the globe is located in highly water-stressed regions, it added.

The report makes a number of recommendations, including prioritizing green hydrogen projects, and carefully considering water impacts, and well as incentivizing efficiency in energy conversion and water consumption.