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Nikola Solic / Reuters
This file photo shows soldiers from the U.S. Army preparing to go on patrol in Afghanistan. Soldiers in the field need up to 7 gallons of water per day.
A new technology to harvest drinkable water from diesel exhaust could help the U.S. military become more nimble and mobile as it engages in conflicts around the world.
Warfare is hot, dirty, and exhausting work that requires a steady stream of water to slake thirst, prepare meals and maintain healthy hygiene — up to nearly 7 gallons a day per person.
Supplying that water to soldiers increases vulnerability to military personnel and limits the tactical use of field troops, according to researchers at the Department of Energy's Oak Ridge National Laboratory who are developing the new technology.
Their solution is to use the fuel that the military burns to run its tanks, Humvees, generators and other machines that power field operations. When fuel is combusted, it gets oxidized and produces carbon dioxide and water.
"Theoretically, one gallon of diesel should produce one gallon of water," project leader Melanie Debusk explained to me Wednesday. While all of that water isn't recoverable, the system her team is developing should be able to get back between 65 and 85 percent of it.
"Considering how much fuel the military uses in the field that would be a significant contribution to the water issue," she noted.
For example, a Humvee, which has about a 25-gallon tank, could provide enough water for about three soldiers per tank of fuel burned.
Capillary condensation
The concept under development is based on the process known as capillary condensation, which contrasts to thermodynamic condensation — that is cooling the air so that water drops out of it.
"With capillary condensation, we've got tiny capillaries in our porous, tubular inorganic membranes," Debusk said, explaining that the system is like a hollow steel tube with porous walls. Water condenses by capillary action in the pores.
This liquid water is constantly drawn off from the outside of the tube, allowing more water to be condensed from the exhaust passing through the center of the tube.
"Based on the rules of capillary condensation, you should be able to condense more water out at a given temperature compared to if you cooled air directly to that temperature and were relying on thermodynamic condensation," Debusk added.
In addition, capturing water vapor in this way leads to approximately a 100-fold reduction in contaminants in the water because "you are condensing it in these tiny pores and you are displacing it continually," she said.
As a result, the contact time between water soluble gases such as nitrogen dioxide and the condensed water is eliminated.
Water shortage solution?
According to the team, this system is an improvement over an earlier technology proposed to convert diesel exhaust to water that was based on thermodynamic condensation, which was heavy, bulky and consumed too much energy to run heat exchangers.
The U.S. military deemed that system "undeployable," according to the Oak Ridge National Laboratory. The lab is pushing for full-scale development of its system within the next few years. The budget required to do so is about $6 million, according Debusk.
If it works at full scale, maybe this is a solution to help cope with looming water shortages? Feel free to weigh in with your comment below.
More stories on water solutions:
- Turning air into water? Gadget does just that
- Things you didn't know about water
- Re-using 'Graywater:' Next step in conservation
- Experts warn of severe water shortages by 2080
John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).
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As a reverse idea to this, in the 70's during Carter's reign of terror many farmers were adding water to their diesel engines by way of Mist injection to make diesel fuel go further. Once the engine was started, a water mist was added which reduced the amount of diesel being used, but supposedly allowed the engine to have better efficiency of the fuel that was burned with no drop in power.
That would still be something to look into now that we have high fuel prices. Then using the scenario in this article, there would be even more water to recover.
There are a few issues with that. First, a portion of that water would have to be piped back into the engine for reuse, thus limiting the water recovery from this process. Second, I would be highly concerned about the prolonged exposure to additional water vapor inside the cylinder, regarding possible degradation of the piston, due to small quantities of water accumulating after the engine is shut down(unless the army has specified otherwise, most engines still use some form of iron in the piston rod, which is subject to corrosion).
I'm confused. What water would need to be re-directed to the engine? If your refering to the radiator system, that is a closed loop system that requires chemical maintenance on a limited schedule. That goes along the same line of thinking, what additional water in the cylinder? They are not modifying the vehicles at all, they are simply taking the exhaust and refining it.
@ Delfairchild...surely you mean Bush II Rein of Terror? At least Carter had a good heart. Bush and thugs destoyed the economy, two wars off the books, tax breaks/subsidies for the SUPER rich that destroyed/shipped jobs overseas that ballooned the USA's debt to 14 Trillion dollars. Carter was innocent of all that. Carter never broke the trillion mark but "Saint Reagan" DID! Carter was an excellent President.....King Bush was THE WORST!!!! The GOPs version of BIG Govenment (The "Patriot Act" and regulating women, outlawing Marriage for some,etc) Besides Bush II is ANTI-science which surprises me that you would read science articles.
Wonder what could be harvested from your exhaust, kdc43.....
Here's an article on "water injection" in both piston and turbine engines: "(engines)".
wow kdc43, you are completely ignoranty here. Bush didnt explode the national debt, and neither has Obama, it is CONGRESS that controls spending and they are responsible (and it was a democratic congress in particular that added more debt in 4 (2 bush, 2 obama) years then the GOP congress under Bush's first 6 years before being voted out). So please do the world a favor and do reproduce, we do not need people like you polluting the gene pool.
I'm waiting for some green to pipe up that not letting the water vapor in the exhaust go back to the atmosphere will contribute to global warming. They have already tried to turn the positive of plants losing less water with higher CO2 levels into a negative claiming it will result in less rain. The fact that more moisture would stay in the ground in the first place would mean less rain would need to fall was totally lost on them.
You do realize that you are referring to the left wing counterpart of the tea party, don't you?
Your idea is a nonstarter from the point that the military would then have to bring in even more water. As domestic use, not enough info from you on the long term affects of adding water to fuel. Hope they are able to make it patitable as well as potable.
That's the point there is already water in the exhaust from the combustion process (water is in the fuel already, and in the combusted air, and also as a result of the chemical reactions)
There is no "water in the fuel already". The water is formed through combustion and chemical reactions. The Chemical formula for Diesel is C10H20 to C15H28. Water is H2O. THe oxygen comes from the atmosphere, not the fuel. That's why it's theoretically possible to get 1 gallon of water from 1 gallon of diesel. It's not magic.
Don't waste the CO2. Compress it and add it to the recovered water for seltzer at the Officers Club.
Israel has technology to get water out of the air using a desiccant to trap the water.
http://www.mfa.gov.il/MFA/Israel+beyond+politics/EU-squeezes-drinking-water-from-air-3-Nov-2008
Given Golbal Warming this should be a priority project of the national government. We should not a allow a private monopoly to dictate amarica's water supplyfuture.
Are you freaking kidding me? You have an opinion about ANYTHING and you can't spell America correctly? Before you make comments on how to deal with monopolies and water policy in the United States, please do your country a favor and go back to 4th grade... you'll prove to be a much more valuable member of society afterwards.
Interesting article, but I can't believe where some people are trying to take the discussion. Can't we just be satisfied with someone using ingenuity to come up with something useful for our troops? Clean water is essential for survival and I could see this technology being potentially quite useful in remote locations too.
Any combustion reaction with (CH)n hydrocarbons produces CO2 and water. You could combust grass in a high-pressure bomb calorimeter and get some water out of it. Just lighting something on fire will not produce water since it's not particularly hot...
Regan/Bush/Chaney - precisely and exactly why (provably) why we are in what seems like an irreversibly spiral downward and my man Obama seems to be powerless to stop it.
That said, the article that it is the exhaust that is processed. OUTSIDE, nowhere near pistons or other internal engine parts. Please see Mr. Docsuby' not above. Note: "With capillary condensation, we've got tiny capillaries in our porous, tubular inorganic membranes..." There is no mention os cylinders, just "tubes."
Nothing new here. German zeppelins did this to keep from destroying their trim as they used up their fuel. Very old technology.
What an idea. I could see many offshoots for this capillary distillation technology. But what about contamination clogging up the capillaries? That's probably why they need at least $6M to figure out.