How the Navy Might Spin Seawater Into Jet Fuel

US Iran
AP/U.S. NavyThe USS John C. Stennis

Water, water everywhere, and not a drop to drink -- but maybe a drop of alternative fuel? The U.S. Navy is hoping next-generation technology will let it replace petroleum fuels with something much more accessible and abundant: seawater.

"If they made fuel at sea," Naval Research Laboratory chemist Heather Willauer told NextGov this week, "they wouldn't be buying it."

Hydrocarbon fuel is, as the name suggests, made up of hydrogens and carbons. The first step to powering ships and planes with seawater is extracting carbon dioxide (CO2) from seawater. There's actually a lot of CO2 dissolved in the ocean –- at a concentration 140 times greater than in the air, in fact. NRL's way of capturing carbon involves a three-chambered cell that applies electricity to seawater. This cell pulls out carbon dioxide and also produces hydrogen.

Next, the team uses a two-step process to combine the CO2 and hydrogen gases into a liquid soup of hydrocarbons. An iron-based catalyst converts both carbon dioxide and hydrogen gas into a type of hydrocarbon called an olefin (without the catalyst, you end up with a lot of wasteful methane production). For the second step, Navy chemists convert olefins to a jet fuel precursor through a process known as oligomerization –- combining little links of molecules called monomers into a longer, more complex chain called a polymer.

Challenges remain, of course. The initial part of the process does gobble up a lot of energy, and while the technique has become more efficient in recent years, NRL's carbon capture methods could still be more efficient, Willauer told NextGov.

In the fiscal year of 2011 alone, Navy vessels at sea used nearly 600 million gallons of fuel, according to the NRL. The Navy has set a goal of reducing its petroleum use by half by 2015.

In a 2012 analysis published in the Journal of Renewable and Sustainable Energy, Willauer and her colleagues estimated that jet fuel could be made at sea for anywhere from $3 to $6 per gallon. While that's slightly more expensive than what the Navy has been paying for fuel, it may not be for long.

"In nine years, the price of fuel for the Navy could be well over the price of producing a synthetic jet fuel at sea which would not incur the costs associated with logistical storage and delivery," Willauer and colleagues wrote.

If the technology pans out, every Navy ship might be able to make its own fuel. Ships wouldn't have to be refueled by oil tankers -- a rough proposition in stormy weather or in battle.

"A ship's ability to produce any significant fraction of the battle group's fuel for operations would increase the Navy's operational flexibility and time on station by increasing the mean time between refueling," the NRL team wrote.

Pulling carbon dioxide out of the ocean to make jet fuel could also have an additional environmental boon, science writer David Biello noted at Yale Environment 360: reducing the trend of ocean acidification, which is caused by increased levels of CO2 in the ocean and has a range of effects on marine life, including making it harder for shellfish and coral to build their shells.

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I don't see each navy ship producing it's own hydrogen without a nuclear reactor to supply the electricity--at which point you might as well let that electricity propel the ship. It may be more practical to have a hydrogen production ship with a reactor, that then supplies the other ships. I foresee the major carriers and the subs still remaining nuclear..

December 19 2013 at 11:22 AM Report abuse rate up rate down Reply
2 replies to dobravery's comment

I think the thrust of the story is (although not specifically stated!) that nuclear powered aircraft carriers could produce the jet fuel used by their aircraft. Bunker oil burned by non-nuclear powered ships is a very different animal than kerosene, and may be a lot more difficult to produce using this process. I, like you, can't see carrirers and subs being powered by anything other than nuclear power.

December 19 2013 at 11:55 AM Report abuse rate up rate down Reply

dobravery - you seem to have some misconceptions about the role of nuclear reactors in a ship. Nuclear reactors use nuclear fuel as a heat source. Using a heat exchanger high pressure steam is produced. This steam drives several high speed turbines among other things. Some of the turbines propel the ship and some produce electricity, which is used all over the ship.

December 19 2013 at 12:57 PM Report abuse rate up rate down Reply

How about mothballing half of the Navy ships?

December 19 2013 at 10:35 AM Report abuse -1 rate up rate down Reply

Wasn't it like too expensive to make into Fresh Water?

December 19 2013 at 9:28 AM Report abuse +1 rate up rate down Reply

What the writer of this article fails to bring to light is that hydrogen has to be manufactured for this to work. It's not a free ride. It is very cost ineffective to crack hydrogen from sea water. From where does the energy for this hydrogen production come? A reactor? If so, you are still upside down in the energy to energy conversion. Also, creation of olefins on board a ship? You've got to be kidding me. I've worked at an olefins facility and they are highly volatile and unstable. Remember BP Houston a few years back?

December 19 2013 at 9:20 AM Report abuse +2 rate up rate down Reply

Not a drop of respect for the Navy. They are destroying the oceans and marine life as well as everything else they decide is in their way. The Navy won't be happy until everything is dead.

December 19 2013 at 9:17 AM Report abuse -4 rate up rate down Reply

"Ships wouldn't have to be refueled by oil tankers
-- a rough proposition in stormy weather or in battle."

As a former tanker OIC, I know this to be absolute garbage
and simpleminded conjecture by the author(s) and editor.

We train for weather and battle. We did it during WWII despite
the wolfpacks and have not forgotten how.

December 19 2013 at 9:01 AM Report abuse +3 rate up rate down Reply

This is just a bland meaningless article intended to get peoples minds off of the cesspool in washington with this new healthcare monopoly.

December 19 2013 at 8:52 AM Report abuse rate up rate down Reply

Hawaii has been doing this for years...What's new all of a sudden? And why is the Media not interested in what Hawaii has been already doing? hUMMM Might have something to do with "who" tells our Media what to say ....I guess....And how I should think....Etc

December 19 2013 at 7:10 AM Report abuse rate up rate down Reply
1 reply to cessnatx's comment

Can you post any links to information concerning this being done in Hawaii?

December 19 2013 at 9:12 AM Report abuse +1 rate up rate down Reply

The navy would save a lot on fueling costs if they stopped purchasing from crooked suppliers. However, this would entail navy brass forgoing free prostitutes and other inducements...

December 18 2013 at 11:32 PM Report abuse -3 rate up rate down Reply

And then there is the new commercial operation in Iceland that combines CO2 and fresh water to make Methanol that is sold as a petro suppliment in Europe and at a price lower than the cost of the petro. CO2 as renewable energy. The end of the world folk better find another cause.

December 18 2013 at 10:24 PM Report abuse +2 rate up rate down Reply