Scale model WWII craft takes flight with fuel from the sea concept

Apr 07, 2014
A replica of a World War II P-51 Mustang red-tail aircraft was used at the Naval Research Laboratory to test "fuel from the sea" concept. The Naval Research Laboratory has developed and demonstrated technologies for the recovery of CO2 to hydrocarbons that can be used to produce designer fuel. Credit: U.S. Navy photo by Mass Communication Specialist 3rd Class Gregory Pickett/Released

Navy researchers at the U.S. Naval Research Laboratory (NRL), Materials Science and Technology Division, demonstrated proof-of-concept of novel NRL technologies developed for the recovery of carbon dioxide (CO2) and hydrogen (H2) from seawater and conversion to a liquid hydrocarbon fuel.

Fueled by a liquid hydrocarbon -a component of NRL's novel gas-to-liquid (GTL) process that uses CO2 and H2 as feedstock - the research team demonstrated sustained flight of a radio-controlled (RC) P-51 replica of the legendary Red Tail Squadron, powered by an off-the-shelf (OTS) and unmodified two-stroke internal combustion engine.

Using an innovative and proprietary NRL electrolytic cation exchange module (E-CEM), both dissolved and bound CO2 are removed from at 92 percent efficiency by re-equilibrating carbonate and bicarbonate to CO2 and simultaneously producing H2. The gases are then converted to liquid hydrocarbons by a metal catalyst in a reactor system.

"In close collaboration with the Office of Naval Research P38 Naval Reserve program, NRL has developed a game changing technology for extracting, simultaneously, CO2 and H2 from seawater," said Dr. Heather Willauer, NRL research chemist. "This is the first time technology of this nature has been demonstrated with the potential for transition, from the laboratory, to full-scale commercial implementation."

CO2 in the air and in seawater is an abundant carbon resource, but the concentration in the ocean (100 milligrams per liter [mg/L]) is about 140 times greater than that in air, and 1/3 the concentration of CO2 from a stack gas (296 mg/L). 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 percent is bound in bicarbonate.

NRL has made significant advances in the development of a gas-to-liquids (GTL) synthesis process to convert CO2 and H2 from seawater to a fuel-like fraction of C9-C16 molecules. In the first patented step, an iron-based catalyst has been developed that can achieve CO2 conversion levels up to 60 percent and decrease unwanted methane production in favor of longer-chain unsaturated hydrocarbons (olefins). These value-added hydrocarbons from this process serve as building blocks for the production of industrial chemicals and designer fuels.

In the second step these olefins can be converted to compounds of a higher molecular using controlled polymerization. The resulting liquid contains hydrocarbon molecules in the carbon range, C9-C16, suitable for use a possible renewable replacement for petroleum based jet fuel.

The predicted cost of jet fuel using these technologies is in the range of $3-$6 per gallon, and with sufficient funding and partnerships, this approach could be commercially viable within the next seven to ten years. Pursuing remote land-based options would be the first step towards a future sea-based solution.

The minimum modular carbon capture and fuel synthesis unit is envisioned to be scaled-up by the addition individual E-CEM modules and reactor tubes to meet fuel demands.

NRL operates a lab-scale fixed-bed catalytic reactor system and the outputs of this prototype unit have confirmed the presence of the required C9-C16 molecules in the liquid. This lab-scale system is the first step towards transitioning the NRL technology into commercial modular reactor units that may be scaled-up by increasing the length and number of reactors.

The process efficiencies and the capability to simultaneously produce large quantities of H2, and process the seawater without the need for additional chemicals or pollutants, has made these technologies far superior to previously developed and tested membrane and ion exchange technologies for recovery of CO2 from seawater or air.

Explore further: Improving the chances for fuel recovery and carbon sequestration

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Going
3 / 5 (2) Apr 07, 2014
Where exactly is the source of energy in this system? Taking carbon out of CO2 and hydrogen out of H2O takes energy. I guess the catalysts involved need a lot of energy to manufacture and have a limited useful life.
Scottingham
5 / 5 (3) Apr 07, 2014
Going: Aircraft are presumably on aircraft carriers, which are run by fission!!! These carriers have enough fuel to run full-speed for 30 years. Basically, more than they know what to do with.

This is a great development. I had often wondered why they hadn't been doing this. The answer seems to be catalyst tech has caught up...90% efficiency is nuts!
MR166
2 / 5 (6) Apr 07, 2014
This is a green energy system so energy input is never counted. It's hard to feel all warm and fuzzy when it takes 100 calories to produce 50.
Scottingham
3.7 / 5 (3) Apr 07, 2014
MR166, dude, fission provides exponential energy based off its mass. That's there the MC^2 part comes in with the E=MC^2. Take that and translate it into chemical energy (ie carbon chain bonds). While there is a net loss of energy, the liquid fuel is now waay easier to transport and use. It could also be considered 'near carbon neutral' since the carbon source hasn't been sequestered for millions of years.
MR166
4.2 / 5 (5) Apr 07, 2014
I stand corrected. In this case the ability to produce a fuel is far more important than the amount of power used to produce it. The only limiting factor is the amount of space that the equipment needs.
bearly
2.5 / 5 (4) Apr 07, 2014
This could be the end of "big oil", thus you will never see it happen.
Scottingham
3.7 / 5 (3) Apr 07, 2014
bearly...conspiracy theories never hold up if you have more than a superficial understanding of the situation. If this works out, then expect the 'big oil' companies to go whole-hog into it themselves. They have the capital to make it happen. They know their easy ride of just getting out of the ground is coming to a close.

Honestly though, I'd expect a company like Areva (french nuke) to get into it before an Exxon type. This won't work without fission...you need lots of scalable energy in order for this to make sense. Solar/Wind wouldn't work out due to their low energy density per acre.
ubavontuba
3.3 / 5 (4) Apr 07, 2014
Interesting concept! If this is practical, I could envision the rise of a whole new energy sector, based on nuclear power to hydrocarbon conversion.

baudrunner
2.7 / 5 (3) Apr 07, 2014
Yield could be increased substantially using nanopores in Graphene filters. They haven't been invented yet to separate Carbon from Oxygen in water but they will be. The capability currently exists. http://www.pcb007...?a=98255
MR166
4 / 5 (2) Apr 07, 2014
As far as using this method to create a replacement for land based fuels that is a long way off. Giving an aircraft carrier the ability to create it's own jet fuel is invaluable at any energy cost.

Regular non military fuel is another matter. We first have to be able to generate enough base load electric power without using any fossil fuels. Then any excess capacity can be used to create the equivalent of fossil fuels for transportation.
StanFlouride
2 / 5 (1) Apr 08, 2014
They chose a P-51D 338th Fighter Wing Red Tail (aka the Tuskegee Airmen) and they made the pilot white?
rockwolf1000
4.5 / 5 (2) Apr 08, 2014
They chose a P-51D 338th Fighter Wing Red Tail (aka the Tuskegee Airmen) and they made the pilot white?


Good eye! More likely, the model came from the store that way. Some come with multiple decal/coloration schemes but only one pilot sadly.
dav_daddy
5 / 5 (3) Apr 08, 2014
They chose a P-51D 338th Fighter Wing Red Tail (aka the Tuskegee Airmen) and they made the pilot white?


Good eye, I'd say Colorado him in with a marker but that could wind up making it worse depending on how you look at it.

Leaving energy efficiency aside for a moment it said in the article that it cost from $3-$6 per gallon. A quick search shows that kerosene (jet fuel) tracked from .40 cents to $1.50 more than gas over the last year, so assuming a large operation could do so cheaper than the low end of what they currently produce at (with economies of scale and a few subsidies it could be significantly less)

Plus this uses sea water instead of fresh water like other hydrogen schemes this could really be viable!
Urgelt
5 / 5 (2) Apr 08, 2014
Reminds me of hydrogen-fueled schemes, because a common misconception with hydrogen is that it's an energy source. It isn't. It's just a way to convert one form of energy into another form, then use it.

The same misconception is likely to be picked up and perpetuated here. I'll attempt to dispel that notion: we will not be using this process as an energy source, because it isn't one. But it does look like useful liquid fuels can be produced, though at present, not economically.

Whether it's carbon neutral depends on the energy sources used to power the processes involved.

If batteries improve enough, we won't need liquid fuels at all. Just slap battery packs in whatever needs power and off you go. But the energy densities required to match liquid fuels are probably a long way down the road.
Eikka
5 / 5 (1) Apr 08, 2014
Solar/Wind wouldn't work out due to their low energy density per acre.


Power lines are invented. You can collect from a larger area and transmit the power to the coastline to be turned into fuel. It's just a matter of whether the process needs to be running continuously to work.

But it does look like useful liquid fuels can be produced, though at present, not economically.


$4-6 per gallon is cheap for most of the world. Many countries pay $8-9 per gallon and more.

If batteries improve enough, we won't need liquid fuels at all.


Batteries will never be convenient in the same sense. When you take a minute to pour a gallon of fuel in your tank, you're transferring energy at a rate of 2.3 Megawatts. That's comparable to powering a whole town.

Even if you had a battery that could hold as much energy, you can't charge it up as fast, and it still loses capacity over time and you have to deal with the material requirements to make and recycle the batteries.
Scottingham
3 / 5 (2) Apr 08, 2014
The land requirements for terrawatts of power through wind or even solar (think 100s of square miles) isn't anywhere near as feasible as a few acres of fission cores. Seriously, it's that big of a difference in power density
Eikka
not rated yet Apr 08, 2014
The land requirements for terrawatts of power through wind or even solar (think 100s of square miles) isn't anywhere near as feasible as a few acres of fission cores. Seriously, it's that big of a difference in power density


You aren't making "terrawatts" with anything.

Not enough cooling water for 2-3 TW of waste heat.
Going
5 / 5 (1) Apr 08, 2014
Synthetic gasoline has a much higher energy storage density than any battery yet developed or hydrogen . It can also utilize the existing infrastructure of gas stations and distribution. With internal combustion engine technology still capable of efficiency improvements Its the obvious way to go for a zero fossil carbon energy supply.
rjnpwr
not rated yet Apr 09, 2014
Assume that the hydrocarbon is C12H26, which is in the mid-range of the hydrocarbons that are claimed to be synthesized. Assume that seawater has 100 ppm CO2 and that all of it can be harvested and converted to fuel, which is very optimistic. To produce one gallon of this fuel you would need to process over 25,000 gallons of seawater at 100% efficiency for the CO2 alone. The issue is how much fuel will be required and what the production rate of the system that will meet this demand will be. This will determine the footprint of the system and the power requirement, which is likely to be significant. Taxing the ships reactor may mean less time between overhauls, which may or may not be a trade that the Navy is willing to make. There should be enough data at this point to make some simple engineering calculations to see if this concept would be practical if the science is worked out. Now would be a good time to do this.
Eikka
not rated yet Apr 12, 2014
Assume that seawater has 100 ppm CO2 and that all of it can be harvested and converted to fuel, which is very optimistic. To produce one gallon of this fuel you would need to process over 25,000 gallons of seawater


The average dissoved CO2 gas concentration in all the waters in all the oceans is about 90 ppm but it's not uniformly distributed.

The point is that more CO2 is liberated from dissolved carbon carrying minerals in the seawater.

Seriously people. Read the article before commenting on it:

both dissolved and bound CO2 are removed from seawater at 92 percent efficiency by re-equilibrating carbonate and bicarbonate to CO2 and simultaneously producing H2.