Hydrogen is a promising fuel because it is abundant, clean, and renewable. Every year, new technology rolls out to support the switch to hydrogen—from how it’s made, to how it’s stored, to how it’s used. New Mexico is a key player in the nation’s energy game, and a system in development at Los Alamos could help the state grow its emerging hydrogen economy.
Hydrogen fuel is produced in two main ways. The first method, called steam methane reformation (SMR), uses water as steam to react with natural gas at high temperatures, which causes molecular hydrogen (H2) to split off. The other method, water electrolysis, uses electricity to pull apart the hydrogen and oxygen atoms of water molecules. Both approaches require water, and New Mexico doesn’t have much to spare. But Los Alamos scientists Alp Findikoglu, Robert Currier, and Prashant Sharan, have found a way to tap into non-traditional water sources for hydrogen-fuel production.
Last year, New Mexico produced more than a million barrels of oil a day, second in the nation after Texas. For every barrel of oil collected, up to eight barrels of water—a combination of ground water and water that was injected into the ground to help bring up oil and gas—are recovered. Produced water, as it is called, contains residual petrochemicals, various salts, and other dissolved solids, so before it can be used for H2 production, it must be cleaned to a very high grade. This is where the Los Alamos technology comes in.
“Our system can clean produced water sufficiently for hydrogen production,” says Sharan. “We’ve got the total dissolved salts below critical thresholds, so this water could be used for either SMR or electrolysis.”
The method, called supercritical water desalination and oxidation, works like this: first, the water is heated and pressurized to an extreme inside a tank—this is the “supercritical” part. Next, oxygen is pumped in to react with the petrochemicals in the water, converting them into carbon dioxide and water—this is the “oxidation” part. Finally, with the petrochemicals removed, the temperature is raised even more, causing the dissolved salts to precipitate out of solution—this is the “desalination” part. (Certain salt solids can then be sold as a commodity, helping to offset costs.)
A key detail of the setup is that the oxidation step doesn’t just remove the petrochemicals from the water—it also releases their stored energy in the form of heat, which is used in the desalination step. The overall energy consumption is about 75 percent lower than current industry methods.
In addition to produced water from oil and gas operations, New Mexico has large underground saline aquifers, whose waters could also be tapped for H2 production. Creative new technology like this, combined with non-traditional water resources, may be the way forward for New Mexico’s hydrogen economy.