Frequently Asked Questions and Common Concerns
Find responses to other frequently asked questions and common concerns about clean hydrogen.
Electrolysis—a process that uses electricity to split water into hydrogen and oxygen—is one of the key pathways for generating clean hydrogen. However, the consumption of water in the electrolysis process is an important concern, particularly in the context of droughts related to climate change in various parts of the United States. Although electrolysis does consume water to generate hydrogen, the water consumed by electrolysis is comparable to the amount of water consumed when hydrogen is produced via the most common method today, steam methane reforming (which uses high-temperature steam to produce hydrogen from a methane source, such as natural gas). It is also comparable to water usage in the refining of petroleum products such as diesel and gasoline. In addition, if the hydrogen is subsequently used in a fuel cell, water is produced as the end product, which completes the cycle, providing an opportunity to replace some of the water consumed in the hydrogen production process.
Deployments of hydrogen production technologies should be optimized to mitigate water impacts in water-stressed regions of the country—for example, through connective infrastructure to other regions that could reduce water usage where shortages exist. The Greenhouse Gases, Regulated Emissions, and Energy use in Technologies (GREET) model can be used to estimate water usage for different hydrogen production methods.1
Furthermore, seawater may be a viable water source for electrolysis since the additional cost of water purification and desalination would not significantly contribute to the overall cost of hydrogen production. This is a promising pathway for regions that have access to seawater. The added cost of desalination would range from approximately $0.01 to $0.04 per kg of hydrogen.2 This would be a relatively small contribution to the total cost of hydrogen produced from electrolysis, which is currently more than $5/kg, and it would not be a significant impediment to achieving the Hydrogen Shot3 goal of producing clean hydrogen for less than $1 per kg. In addition, DOE is funding research into electrolyzers that can tolerate impure water sources, which could further reduce stress on limited resources of clean, fresh water.4,5
1 Argonne National Laboratory, "GREET Model," 2022. https://greet.es.anl.gov/
2 This estimated cost is based on the following: the cost of desalination ranges from less than two-tenths of a cent per gallon to approximately one cent per gallon [J. R. Ziolkowska, "Is Desalination Affordable?—Regional Cost and Price Analysis," Water Resources Management 29, 1385–1397 (2015). https://doi.org/10.1007/s11269-014-0901-y]; and it can take approximately 3.8 gallons of water to produce 1 kg of hydrogen from electrolysis [National Renewable Energy Laboratory, "H2A: Hydrogen Analysis Production Model," 2024. https://www.nrel.gov/hydrogen/h2a-production-models.html].
3 U.S. Department of Energy, "Hydrogen Shot." www.energy.gov/eere/fuelcells/hydrogen-shot
4 U.S. Department of Energy, "U.S. Department of Energy Announces $72 Million for Small Business Research and Development Grants—with $8.6 Million for 43 Hydrogen and Fuel Cell Projects." www.energy.gov/eere/fuelcells/articles/us-department-energy-announces-72-million-small-business-research-and#c5618l
5 U.S. Department of Energy, "Pure Hydrogen Production through Precious-metal-Free Membrane Electrolysis of Dirty Water," Annual Merit Review and Peer Evaluation Meeting, 2022. https://www.hydrogen.energy.gov/pdfs/review22/p187_boettcher_2022_p.pdf