Green hydrogen: A desert full of possibilities

The advantages of green hydrogen are clear - It has the potential to decarbonize many global energy systems. Right now, 96 percent of hydrogen is produced by nonrenewable sources, but green hydrogen has the added benefit of using renewable energy sources like solar and wind power with low carbon intensity.

Solar power potential is greatest in desert conditions such as in the American southwest. Where is it hardest to secure new water supplies, the feedstock for green, electrolytic hydrogen production? Also, arid areas like the American southwest, where water stress (demand divided by available water) is the highest in the country. Guaranteeing water quality and availability are crucial for the production facilities and surrounding communities. For instance, high quality water required for input and cooling is estimated at about 12 tons of water for each ton of hydrogen produced or 2 million gallons per day (MGD) for a 300 MW electrolyzer.

Where water is in short supply, getting permits and legislative approval to secure the water needed is difficult. So the challenge is deploying desert green hydrogen while using less water.

For example, in Lodi, California, the Northern California Power Agency is building a landmark project to site a hydrogen production and cofiring facility next to the Lodi Water Pollution Control Facility. As part of the proposed Lodi Hydrogen Cluster, the Lodi Energy Center project will produce low-carbon hydrogen to reduce the carbon intensity of natural gas power generation. The facility will use recycled wastewater from the water pollution control facility as feedstock.

To take advantage of solar resources in the desert, total water usage for hydrogen production can be economically reduced by large percentages in the following ways:

• Colocate hydrogen production with sustainable sources of water supply. Like Lodi, hydrogen production facilities can be colocated near wastewater treatment plants or other facilities that produce recycled water. You can reduce the need for new demands on groundwater or surface water supplies and beneficially reuse the wastewater that would otherwise end up in a waste stream or evaporation pond. Also, you can select technologies that recover a higher quality of the reused wastewater, achieving more water savings.
  
  
• Design systems with equipment and technology that reduce total water usage. You can reduce overall water demand in the plant lifecycle, from treatment to cooling, by choosing the right equipment. Don’t miss opportunities for efficiencies throughout the design process.
  
  
• Consider waste streams of water treatment. Green hydrogen production requires highly purified water in the electrolyzer system. Treatment technologies such as reverse osmosis, ion exchange, and demineralization produce concentrated brine streams that must be handled. Projects in delicate environmental settings such as deserts should consider strategic wastewater management, such as zero liquid discharge systems that align with local regulatory frameworks.
  
  
• Consider waste heat recovery. While capital intensive, waste heat from the hydrogen production and compression processes may be recovered to drive desalination and brine management and reduce overall cooling requirements.
  
  
• Navigate the water market. It helps to establish close working relationships with water permitting agencies in the local area. For instance, many of the water systems and associated conveyance and storage infrastructure in the southwest are managed so that water may be transferred from faraway places without sending the actual water molecules. A comprehensive understanding of the project’s specific challenges and institutional knowledge from other projects will ease the way over regulatory hurdles.
  
  It can be feasible to implement green hydrogen projects in the desert. We have been working with hydrogen for over 50 years in North America and worldwide. In addition to the Lodi project, we have served as lead technical advisor and stakeholder engagement for one of the world's largest hydrogen supply chain projects, which will deliver hydrogen from Australia to Japan.

Green hydrogen offers a whole host of community benefits, importantly balancing environment with economic growth. Hydrogen has the promise of decarbonizing heavy industrial sectors, helping them along the path to net-zero and towards a circular economy. While we reduce air quality emissions through hydrogen, we need to ensure we manage impacts to existing water systems.