Drinking water from vehicle diesel fuel? Learn how one manufacturer has figured out a new way to quench desert-occupying soldiers’ thirst by delivering potable water converted from exhaust waste.

United Technologies Corp.’s Hamilton Sundstrand unit later this month will deliver two military Humvees to the Army for testing at the Aberdeen Proving Ground outside Baltimore for three months, reported the Wall Street Journal last week. The plan is to convert diesel exhaust from a Humvee into drinking water via technologies developed for the space program, an idea that’s apparently been around for some time.

“This is one of those things where, when you first hear about it, you think the scientists have gone out of their minds,” Robert Leduc, president of Hamilton Sundstrand’s flight systems business, told WSJ.

Well put, Mr. Leduc. Hamilton Sundstrand’s flight systems business includes the water-recovery program.

Soldiers in the desert obviously require a great amount of water for various purposes: drinking, medical, food preparation, bathing and washing clothes. According to the military, a soldier in the desert needs about 20 gallons of water a day; drink-, food- and medical-related water needs to be pure. And transporting the necessary liquid often is limiting for troops, as it leaves them vulnerable during necessarily slow-moving transit.

The water-recovery program, however, is a bit more complex than a soldier simply sipping water from an exhaust pipe.

Built into each standard military Humvee’s truck bed is a complex system that can generate drinking water from vehicle exhaust, recovering water from engine exhaust and purifying as much as half the liquid volume from a tank of fuel. The water from the exhaust system “can produce approximately one gallon of water for every two gallons of fuel used,” reports RDECOM Magazine, or one gallon of clean drinking water for every hour of standard vehicle operation.

Fuel combustion byproducts in motor vehicles include unburned hydrocarbons and H2O. Along with much of the heat, waste products have long been known to be expelled out of the exhaust pipe and into the atmosphere. And scientists in Lexington, Kentucky, discovered a way to filter out usable water vapor.

The water from the exhaust system operation comes about by combining hydrogen, which is already in the fuel, with oxygen in the air, “producing water vapor and exhaust gases.” The gases, rather than exiting the tailpipe, according to WSJ, are “vented through a catalytic converter to bake off as many impurities as possible”; they then run through two heat exchangers for heat extraction and water-vapor condensation into the collection tank, at which point the condensate resembles muddy water and smells of sulfur. The nasty water then runs through a series of carbon filters for removal of impurities. Finally, a chlorine solution is added “to kill bacteria and algae that might form post-purification and then deposits the water in a five-gallon tank.”

Once enough potable water is present in the on-board storage tank, soldiers can draw water from a tap located near the rear passenger side of the vehicle. Of course, actually drinking water that comes from gaseous waste is entirely up to the soldier.

References:

Alchemy in the Desert?
J. Lynn Lunsford
The Wall Street Journal, October 4, 2005
http://online.wsj.com/public/article/SB112838697987459124.html?mod=todays_free_featu

TARDEC debuts system that generates water from exhaust
Paul D. Mehney
RDECOM Magazine
www.rdecom.army.mil/rdemagazine/200311/itf_tardec_water.html

Additional Resource:
Army testing pump that makes water from exhaust
Spc. Bill Putnam
Army News Service, Oct. 14, 2003
http://www4.army.mil/ocpa/read.php?story_id_key=5311