Scientists at the U.S. Naval Research Laboratory (NRL) are developing a process to extract carbon dioxide (CO2) and produce hydrogen gas (H2) from seawater.  Then they catalytically convert the CO2 and H2 into jet fuel by a gas-to-liquids process.

The NRL effort has successfully developed and demonstrated technologies for the recovery of the CO2 and the production of the H2 from seawater using an electrochemical acidification cell, and the conversion of the CO2 and H2 to hydrocarbons that can be used to produce jet fuel.

Electrochemical Acidification Carbon Capture Skid. Click image for more info.

NRL research chemist Dr. Heather Willauer said, “The potential payoff is the ability to produce JP-5 jet fuel stock at sea reducing the logistics tail on fuel delivery with no environmental burden and increasing the Navy’s energy security and independence.”  JP-5 is very close chemically to kerosene and diesel.

Willauer continues, “The reduction and hydrogenation of CO2 to form hydrocarbons is accomplished using a catalyst that is similar to those used for Fischer-Tropsch reduction and hydrogenation of carbon monoxide. By modifying the surface composition of iron catalysts in fixed-bed reactors, NRL has successfully improved CO2 conversion efficiencies up to 60%.”

Technically, the NRL has developed a two-step laboratory process to convert the CO2 and H2 gathered from the seawater to liquid hydrocarbons. In the first step, an iron-based catalyst can achieve CO2 conversion levels up to 60% and decrease unwanted methane production from 97% to 25% in favor of longer-chain unsaturated hydrocarbons (olefins). Then in step two the olefins can be oligomerized (a chemical process that converts monomers, molecules of low molecular weight, to a compound of higher molecular weight by a finite degree of polymerization) into a liquid containing hydrocarbon molecules in the carbon C9-C16 range, suitable for conversion to jet fuel by a nickel-supported catalyst reaction.

The raw materials are abundant.  CO2 is an abundant carbon source in seawater, with the concentration in the ocean about 140 times greater than that in air. Two to three percent of the CO2 in seawater is dissolved CO2 gas in the form of carbonic acid, one percent is carbonate, and the remaining 96 to 97% is bound in bicarbonate. When processes are developed to take advantage of the higher weight per volume concentration of CO2 in seawater, coupled with more efficient catalysts for the heterogeneous catalysis of CO2 and H2, a viable sea-based synthetic fuel process could be developed.

The NRL effort made significant advances developing carbon capture technologies in the laboratory. In the summer of 2009 a standard commercially available chlorine dioxide cell and an electro-deionization cell were modified to function as electrochemical acidification cells. Using the novel modified cells both dissolved and bound CO2 were recovered from seawater by re-equilibrating carbonate and bicarbonate to CO2 gas at a seawater pH below 6. In addition to CO2, the cells produced H2 at the cathode as a by-product.

Note that the oceans offer a huge reserve of raw materials for fuel production.

The completed studies of 2009 assessed the effects of the acidification cell configuration, seawater composition, flow rate, and current on seawater pH levels. The data were used to determine the feasibility of this approach for efficiently extracting large quantities of CO2 from seawater. From these feasibility studies NRL successfully scaled-up and integrated the carbon capture technology into an independent skid, or “lab on a pallet’ so to speak, called a “carbon capture skid” to process larger volumes of seawater and evaluate the overall system design and efficiencies.

The carbon capture skid’s major component is a three-chambered electrochemical acidification cell. The cell uses small quantities of electricity to exchange hydrogen ions produced at the anode with sodium ions in the seawater stream. As a result, the seawater is acidified. At the cathode, water is reduced to H2 gas and sodium hydroxide (NaOH) is formed. This basic solution may be re-combined with the acidified seawater to return the seawater to its original pH with no additional chemicals. Current and continuing research using the carbon capture skid demonstrates the continuous efficient production of H2 and the recovery of up to 92% of the CO2 from seawater.

The carbon capture skid has been tested using seawater from the Gulf of Mexico to simulate conditions that will be encountered in actual open ocean processing.

The NRL group is working now on process optimization and scale-up.  Initial studies predict that jet fuel from seawater would cost in the range of $3 to $6 per gallon to produce.

Willauer points out, “With such a process, the Navy could avoid the uncertainties inherent in procuring fuel from foreign sources and/or maintaining long supply lines.”  During the government’s fiscal year 2011, the U.S. Navy Military Sea Lift Command, the primary supplier of fuel and oil to the U.S. Navy fleet, delivered nearly 600 million gallons of fuel to Navy vessels underway, operating 15 fleet replenishment ships around the globe.

The Navy’s fuel supply system works at sea, while underway and is a costly endeavor in terms of logistics, time, fiscal constraints and threats to national security and the sailors at sea.

It’s a brilliantly insightful use of the environment.  Moreover the technology will help clean the seawater of an overcharge of CO2 and that is actually a recycling of fossil fuel additions to the environment.

Entrepreneurs are going to realize the Navy’s work could be an industrial boon to fuel production as well as shorten the carbon cycle.  While the Navy thinks $3 to $6 for production cost, the private sector would very likely drive that cost far further down.

It’s not hard to imagine that in a few years most of the oil business might simply be at sea, harvesting CO2 and H2, making petroleum products from a recycling of the CO2 from the past use of fossil fuels.

Many may complain that the military is a waste, poor policy, or other notions that fly in the face of human nature.  But in the past few decades the U.S. military, filled with volunteers, can make significant contributions, and now perhaps solve what has been thought to be an intractable problem.

Go Navy!


11 Comments so far

  1. brian t on September 25, 2012 4:18 AM

    Not a word about the energy requirements of this process? They must be enormous. The Fischer-Tropsch process itself has an energy efficiency of 25-50%, and this Navy process is even more involved.

    So unless there’s been some miraculous reversal of the 2nd Law of Thermodynamics of which I wasn’t aware, this process consumes at least 2x as much energy as is delivered in the resulting fuel. Which is fine for a nuclear-powered aircraft carrier with energy to spare, but if you’re talking about commercial applications in the middle of the ocean … Solar?

  2. David Martin on September 25, 2012 6:01 AM

    Good point about the needed energy input.
    That is what I was looking for info on.

    There is no way at all that you could use solar – the simplest area calculations show that enormous floating fields would be needed – how are you going to shift them to where the navy needs to operate? How would they be moored?

    No problems however about using nuclear, as the aircraft carrier could produce fuel for the whole battlegroup.

    We have no information at all on how much is needed.

  3. Matt Musson on September 25, 2012 7:23 AM

    With a mass produced Thorium reactor sitting on the dock of the bay – this type of energy conversion would be economically feasible. For the Navy – not having to maintain stocks and transport fuel across the globe makes this a bargain.

  4. Al Fin on September 25, 2012 8:57 AM

    As long as they have a massive amount of cheap energy to burn, they can do this until the cows come home.

    But for all the carbon hysteria flying around, CO2 is only 0.4 % of the Earth’s atmosphere, which is not particularly abundant or concentrated.

    And for all the “ocean acidification” hype and madness, most of the CO2 (about 95%) in oceans turns into bicarbonate (HCO3- , a buffer) almost immediately, and then into other carbon forms even more remote from CO2.

  5. Pete on September 25, 2012 8:58 AM

    Yay! I feel vindicated. I’ve been saying for some time that capturing CO2 from seawater would be much more efficient than doing it directly from air. Now that I know some research groups are working on it I feel a bit less stupid for not knowing why that wouldn’t work.


  6. James Crowe on September 25, 2012 9:30 AM

    Throughout history a lot of technological innovations have come from the military’s need to solve problems. This in turn eventually filters out to the public domain. If this can be successfully done, economically, it would revolutionize the world! (PS: I hope the powers that be don’t squash it.)

  7. karl smith on October 23, 2012 10:46 AM


  8. karl smith on October 23, 2012 10:49 AM

    this will find the oil industries in a tail spin

  9. Walt O'Brien on October 24, 2012 12:09 AM

    F-T water gas shift efficacy all comes down to the catalyst, not energy input per se.

    Practically every innovation in power generation technology traces back to US Navy innovation, whether it is steam turbines, combustion turbines, boilers, heat transfer and most importantly the development of engineering design codes for rotating equipment and power generation tools in general.

    Now if they only could win a football game every now and then LOL

  10. Bill Hanners on October 24, 2012 6:40 AM

    “The devil is in the details.”
    Aircraft carriers are high speed ships, needing high speed to launch and recover aircraft as well as moving quickly to venues of military interest, so burdening these ships with significant loads of chemical processing equipment and power demands does not make sense. Nuclear-powered aviation fuel generating ships as part of a battle group create political questions that seem at odds with current practices, although our president has identified aircraft carriers as part of our current “smaller” navy. I suspect the current producers of aviation fuel will make it difficult to displace them from the fueling cycle even if an efficient technology is developed. It looks like the time for this technology is not yet here. When is “tomorrow?”

  11. Lexy on September 7, 2013 1:36 PM

    Al Fin said “But for all the carbon hysteria flying around, CO2 is only 0.4 % of the Earth’s atmosphere.” and then goes on a rant against ocean acidification. It is worth pointing out that he is off by an order of magnitude. It’s < 0.04% or 400ppm. To give you some perspective, at 1000ppm, you would have problems with concentration. 4000ppm would be lethal. If you were to travel back to the early Cretacious period, you would not be able to survive for long breathing the atmosphere. The point of this is that it took millions of years for us to adapt to current levels and that concentration is increasing at an alarming rate from 387ppm in '09 to 400ppm today.

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