For centuries navies used a renewable energy form as a means of propulsion.
Now the U.S. Navy is investigating another potentially limitless fuel source to produce JP-5 jet fuel – seawater.
The U.S. Naval Research Laboratory (NRL) is developing the chemistry for producing jet fuel from renewable resources in theatre. The process envisioned would catalytically convert carbon dioxide and hydrogen directly to liquid hydrocarbon fuel used as JP-5.
And how exactly would this alchemic sleight of hand be performed?
By extracting CO2 to produce H2 gas from seawater and subsequently catalytically converting it into jet fuel by a gas-to-liquids process.
NRL research chemist Dr. Heather Willauer said, "The potential payoff is the ability to produce JP-5 fuel stock at sea reducing the logistics tail on fuel delivery with no environmental burden and increasing the Navy's energy security and independence. 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 percent. With such a process, the Navy could avoid the uncertainties inherent in procuring fuel from foreign sources and/or maintaining long supply lines."
Note the comment “at sea.” The process would eliminate the time-consuming and risky process of refueling at sea, theoretically allowing each of the U.S. Navy’s 10 operational Nimitz-class carriers to produce their aircrafts’ fuel while underway.
The NRL has now successfully developed and demonstrated technologies for the recovery of CO2 and the production of H2 from seawater using an electrochemical acidification cell, and the subsequent conversion of CO2 and H2 to organic hydrocarbons that can be used to produce jet fuel.
The project, if successful, would add to the Navy’s desire for a self-sustaining carrier task force. Nimitz-class carriers are already independent of the fuel chain logistic because of their nuclear capacity – such a development would subsequently free them from the need to replenish their aircrafts’ fuel reserves as well, leaving them needing only to restock food and ammunition supplies, allowing them greater operational autonomy.
So, how far forward is this process?
In the past three years the NRL has made significant advances developing carbon capture technologies in the laboratory, having begun by utilizing a standard commercially available chlorine dioxide cell and an electro-deionization cell were modified to function as electrochemical acidification cells, whereby 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.”
Again, according to the NRL website, “NRL has developed a two-step process in the laboratory to convert the CO2 and H2 gathered from the seawater to liquid hydrocarbons. In the first step, an iron-based catalyst has been developed that can achieve CO2 conversion levels up to 60 percent and decrease unwanted methane production from 97 percent to 25 percent in favor of longer-chain unsaturated hydrocarbons (olefins).In the second step these 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 principle has been proven – can it be ramped up to provide JP-5 for task forces at sea, spread around the globe?
The NRL website is silent on the possibility of full-scale production. Most 102,000-ton Nimitz-class carriers, the largest warships ever built, mount aerial forces of 50 TACAIR air wing of up to 82 aircraft, a usual mix of: 12 F/A-18E/F Hornets, 36 F/A-18 Hornets, four E-2C Hawkeyes, four EA-6B Prowlers fixed-wing a brace of four SH-60F and two HH-60H Seahawk helicopters.
But it is one thing to prove a fuel conversion technology, another to implement it.
Will Neptune permit the U.S. Navy to mine the liquid gold of his realm?
Watch this space. This might be the biggest naval propulsion revolution since Britain’s Royal Navy reluctantly abandoned sail.
By. John C.K. Daly of Oilprice.com
1 gallon of kerosene has 39 KW-hr of energy
1 Nimitz carrier has 1.1 GW of thermal power available
Let's set aside 10% of power for fuel.
That's 110 MW. Or 2800 gallons/hr at 100%.
Assume overall 30% thermal to kerosene efficiency given the need to generate both carbon and hydrogen and the less than 50% efficiency of the FT process.
That's 800 gallons of kerosene per hr using 10% of the reactor power.
A Nimitz carries 3 million gallons of kerosene.
That would take about 1/2 year to produce.
Shaky, very shaky.
Think of it, oil/gas flows, and is economic when tapped tens of thousands of feet below and much more than that sideways (natural flow or via hydraulic fracturing). Only gold is economic even close to that, at vast more profit per pound!
Maybe algae is an option, even though that is also closed loop, albeit from sunlight, and already about 30% is oil when stressed (and most of our petroleum came from it originally). This above story is not important except to naval strategists. For our lives, oil and gas will not be found lacking in competition with any usual portable synthetic, save algae, it seems.
Cheap energy from a finite source is what has driven our economy for many years and it isn't so cheap anymore. So efforts to hinder other forms of energy are unwise.
This would appear to be incorrect given what the Navy Research Lab press release says. The dissolved CO2 in seawater will be extracted, and combined with hydrogen from the water molecules to create the hydrocarbon feedgas for the Fischer Tropsch GTL process.
And IMHO the assessment above allocates far too little power to the process onboard a carrier. While the exact utilization of the reactors' power is classified, it's unlikely their duty cycle is such that there would be only 10% of the ship's power available for auxiliary functions such as producing jet fuel. If the ship is steaming along at 25kts and not conducting flight operations there'd have to be a pretty large power margin which something like fuel production could utilize.
Of course it could be an incentive for the US Navy to pursue something other than a light water reactor after the A1Bs start getting installed in the CVN-78 class. A breeder reactor, whether an integral fast reactor like the travelling wave reactor (if the USN wants to deal with sodium coolant) or a thorium breeder could have its waste heat used to split hydrogen and oxygen from water, and to supply the FT gas to liquid fuel process with heat, all without impinging upon the ship's propulsion needs.