The U.S. Naval Research Laboratory (NRL) has been granted the first U.S. patent for a method to simultaneously extract carbon dioxide and hydrogen from seawater. The process provides all the raw materials required for the production of synthetic fuels at sea or in remote locations.

The carbon dioxide and hydrogen recovered from the seawater as feedstock can be catalytically converted to hydrocarbons in a second additional synthetic process step.

The Electrolytic Cation Exchange Module (E-CEM), successfully demonstrated as a proof of concept, provides the Navy the capability to produce fuel stock in the form of liquefied natural gas, compressed natural gas, marine naval fuels and kerosene-based jet fuels. Synthetic liquid hydrocarbon fuel production can offer significant logistical and operational advantages to the Navy by reducing both its dependency on in-theater fossil fuel availability and the vulnerabilities resulting from unprotected fuel delivery at sea.

Diagram of the Electrolytic Cation Exchange Module (E-CEM). Image credit: U.S. Naval Research Laboratory.“A ship's ability to produce a significant fraction of the battle group's fuel for operations at sea could reduce the mean time between refueling and increase the operational flexibility and time on station,” says U.S. Naval Reserve Commander Felice DiMascio, one of the technology's co-inventors. This will allow the Navy to reduce the logistics tail on fuel delivery with the potential to increase the force's energy security and independence while minimizing the impact on the environment, he adds.

According to NRL research chemist Dr. Heather Willauer, a second-generation, larger-scale E-CEM research prototype will be demonstrated at NRL's Marine Corrosion Facility, in Key West. “Using a scaled-up, second-generation E-CEM prototype, we will substantially increase CO2 and H2 production capable of producing up to one gallon of fuel per day, an increase nearly 40 times greater than with the earlier-generation E-CEM,” she says.

To accommodate increased feedstock production, NRL is also scaling up the catalyst system to synthesize fuel from CO2 and H2—moving from a small plug-flow chemical reactor to a large-scale chemical reactor.

“Basically we are optimizing both processes separately—CO2 and hydrogen production and recovery, and synthesis of hydrocarbons from CO2 and hydrogen," Willauer says. “Since we will be producing enough feedstock in the near future, we envision integrating the two processes at our Key West facility to further evaluate how full-scale, end-to-end production might evolve.”

The team hopes to have the two processes operating by late 2016.