Navy eyes turning sea water into jet fuel

8:10 AM, Oct 15, 2012   |    comments
MC1 DAVID MCKEE / NAVY
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(NavyTimes.com) - The Navy's next source of renewable fuel is something you know very well: the ocean itself.

The Naval Research Laboratory and the Office of Naval Research are working on a project that would turn ocean water into JP-5 aviation fuel, the lifeblood for all of the Navy's aircraft.

The technology is about a decade away from becoming a reality, researchers say. But if it works, it would be a major pivot in the way the Navy operates.

It would allow a carrier air wing to fly longer, without having to bring more fuel onto the carrier. It would protect ships from risky replenishments at sea. And it would reduce reliance on a fluctuating petroleum market.

In short: It would revolutionize the way carrier air wings fly, the way carrier strike groups deploy and how Military Sealift Command provides some 600 million gallons of fuel to ships around the world.

As one study in the Journal of Renewable and Sustainable energy put it, turning the ocean into fuel is "game changing."

But by no means will this be an easy task for researchers.

The process hinges on the ability to isolate molecules in ocean water, then rearrange their atoms into JP-5, the fuel that not only powers Navy aircraft but is also approved for ship engines.

ALTERNATE ENERGY BREAKDOWN

According to the journal article, which was written by Navy researchers, here's how 100,000 gallons of JP-5 could be made in a day:

Step 1: A processing plant would extract carbon dioxide from 2.35 billion gallons of water - enough to fill the 2012 Olympic swimming pool 2,400 times. This water would yield about 11.9 million gallons worth of carbon dioxide.

Step 2: Another process will produce hydrogen from ocean water. Through reverse osmosis, fresh water will be extracted from ocean water. The two hydrogen atoms from the freshwater molecules will be separated from the oxygen atom. The hydrogen atoms will be collected while the oxygen atoms will be vented away.

Step 3: The hydrogen and carbon dioxide from the first two steps will be used in a catalytic conversion process. The end result is water, heat, and, most importantly, synthetic hydrocarbon, or fuel. Theoretically, the process could be tailored to produce any sort of hydrocarbon fuel, not just JP-5, according to the report.

The leftover water and heat generated could be harnessed and recycled into the system, making it more efficient.

This process would require an outside energy source to cause the various reactions. Nuclear power systems, such as the ones used on aircraft carriers and submarines, could be one option. Another could be ocean thermal energy conversion, a process where the temperature differences between warm water near the ocean's surface and colder water at deeper depths are used to turn an engine and create electricity.

The study doesn't answer some big questions, however.

For example, how would all the necessary equipment to process hundreds of thousands of ocean water per day fit on an aircraft carrier?

To be determined.

"The key is funding research to reduce the power needed for the process, so more fuel can be made," said Heather Willauer, a NRL chemist and one of the writers of the study. "In addition, research focus should be directed toward reducing the size, weight and footprint of the technologies to make it feasible for a sea-based process."

The analysis estimated fuel from this process would cost between $3 and $6 per gallon, including initial start-up costs. The report cited the Navy's 2011 average cost for JP-5 at $3.51; media reports have put that number closer to $4. These prices don't include shipping and storage costs, which would be cut drastically or eliminated by making JP-5 at sea.

"Historical data suggest that in nine years, the price of fuel for the Navy could be well over the price of producing a synthetic jet fuel at sea," the journal article says.

Navy Secretary Ray Mabus has set goals to cut the Navy and Marine Corps' use of fossil fuels, calling for using alternative fuels for 50 percent of the Navy Department's total energy usage by 2020.

His plan has come under attack, largely from Republicans, who say the Navy should not pursue alternative fuel program until alternative fuels are more cost-effective. The Navy's work in alternative liquid fuels has used a blend of traditional fuels mixed with either an algae- or camelina-based based fuel.

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