Seawater Carbon Capture Process Receives US Patent

The NRL, Material Science and Technology Division, has been granted the first U.S. patent for a method to simultaneously extract carbon dioxide and hydrogen from seawater. This single process provides all the raw materials necessary for the production of synthetic liquid hydrocarbon fuels.

Issued April 5 by the United States Patent and Trademark Office (USTPO), patent #9303323 names co-contributors and inventors: Cmdr. Felice DiMascio, U.S. Navy Reserve; Dennis Hardy, NRL; M. Kathleen Lewis, Office of Naval Research (ONR); Heather Willauer, NRL; and Frederick Williams, NRL.

Synthetic fuel production can offer significant logistical and operational advantages to the Navy by reducing dependency on future in-theater fossil fuel availability, and by reducing the vulnerabilities resulting from unprotected fuel delivery at sea. The E-CEM, developed at NRL, provides the Navy the capability to produce fuel stock (LNG, CNG, F-76, JP-5, etc.) at sea, or in remote locations. 

"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," said DiMascio. "Reducing the logistics tail on fuel delivery with the potential to increase the Navy's energy security and independence, with minimal impact on the environment, were key factors in the development of this program." 

Located at NRL's Marine Corrosion Facility, Key West, Florida, the E-CEM has successfully demonstrated proof-of-concept for a simultaneous recovery process of carbon dioxide (CO2) and hydrogen (H2) from seawater. The carbon dioxide and hydrogen gas recovered from the seawater as feedstock are catalytically converted to hydrocarbons in a second additional synthetic process step.

"Building on the success of the first exchange module, we have scaled up the carbon capture process to improve efficiency and substantially increase feedstock production," said Dr. Heather Willauer, research chemist, NRL. "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."

To accommodate increased feedstock production, NRL is also scaling up the catalyst system to synthesize fuel from CO2 and H2. Having fully realized the product distribution of hydrocarbons using a small plug flow chemical reactor, NRL has recently partnered with a commercial entity to test the catalyst using their 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 said. "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."

At these scales, Willauer contends there will remain several issues to resolve; however, the team hopes to have the two processes operating at Key West later this year.