The Pee-Mobile

The following is an article from Uncle John's Heavy Duty Bathroom Reader.

We wrote a paragraph about this in Uncle John's Unsinkable Bathroom Reader and it fascinated us so much that we wanted to share more details. It's real science …and it could be coming to an automobile near you soon.


Dr. Gerardine Botte is an Associate Professor of Chemical Engineering at Ohio University. She's also the founder and director of the school's Electrochemical Engineering Research Laboratory (EERL). Among its many projects, the EERL develops technology for devices known as fuel cells.

Fuel cells are devices that convert a fuel of some kind (Botte's group was working on hydrogen) into electricity. They've been around for a long time -NASA used them for the Apollo moon landings in the late 1960s and early '70s. But they've never been commercially viable, thanks in large part to the high costs associated with obtaining and storing the hydrogen.


One way to obtain hydrogen is to pass an electric current through water to separate the hydrogen atoms -the "H" in H20- from the oxygen atoms -the "O"s- using a process called electrolysis. Because the hydrogen and oxygen atoms are bound together very tightly, it takes a great deal of electricity to break these bonds.

Another problem with this technique is that fresh water works best for fuel-cell conversion …and it's scarce. Only three percent of the water on earth is fresh; the rest is salt water. And very little of that three percent is available to humans for drinking, crop irrigation, and other uses. So it's doubtful that hydrogen will ever be extracted from clean, fresh water on a large scale.

But what about dirty fresh water? That's the idea that came to Dr. Botte several years ago when she was driving home from a conference on fuel cell technology: Why not extract hydrogen from wastewater, which is widely available, virtually free? Botte soon narrowed her focus to one waste stream in particular: urine.

PEE 101

Urine in wastewater contains ammonia (NH3), a compound consisting of one atom of nitrogen and three atoms of hydrogen. And as Dr. Botte confirmed when she subjected urine to electrolysis, it's a good candidate for hydrogen production because the hydrogen and nitrogen atoms are not bound together as tightly as the hydrogen and oxygen atoms in water are.

Only five percent as much energy is needed to break the ammonia molecules apart, and because each molecule contains three hydrogen atoms, not two as in H20, more hydrogen is freed each time a molecule is split up. Less energy spent and more atoms freed makes extracting hydrogen from urine much cheaper than extracting it from fresh water -90cents for the energy equivalent of a gallon of gas vs. $7.10 for hydrogen electrolyzed from water, Botte says. And best of all, fuel cells provide clean energy, because when hydrogen and oxygen are combined to generate electricity, the only "exhaust" created by the process is water (which could be drunk to aid in the production of more urine). No greenhouse gasses are released at all.

With an estimated five million tons of ammonia entering the United States waste stream as human and animal urine each year -enough to provide electricity to 900,000 homes- the supply of "raw materials" for hydrogen production is enormous and almost completely untapped. But not for long: Botte sees a day when hydrogen extraction will be a standard function of wastewater treatment plants. "Ammonia," she says, "is our future fuel."


(YouTube link)

As of the fall of 2009, Botte's pee-powered "electrolyzer" prototype was about the size of a paperback book and produced less than one watt of power, not even enough to light an incandescent light bulb. But Botte says the technology is ready to be scaled up to car size. "With the right partnership, I believe we could have pee-powered cars capable of 60 miles per gallon on the road within a year," she told Wired magazine.

And if her predictions are accurate, cars powered by fuel cells will have pee tanks, just as cars today have gas tanks, because hydrogen is much easier to store as a component of wastewater than in its pure form. Pure hydrogen is a gas; it must be kept extremely cold and stored in pressure tanks to be useful as a fuel. Botte's design calls for the urine to be converted into hydrogen right inside the automobile, and only as needed, eliminating the cost and difficulty of storing hydrogen in its pure form.

But you still won't be able to pee your way to work, unless you have a medical condition or work really close to home. A healthy adult produces only 1.5 quarts of urine a day, not enough to get very far. "I wish we humans produced enough urine to run a whole car," Botte says. "Maybe we could run some minor applications, like the car stereo or something like that."

This version is called the GreenBox. (YouTube link)



Here are a few more waste products with real potential to become the fuels of the future:

* Animal dung. Professor Botte isn't the only person pondering the power of pee: Scientists at Japan's Obihiro University have developed a method of obtaining ammonia from animal urine and dung by fermenting it in an oxygen-free environment. As with Botte's technique, the ammonia is electrolyzed to separate out the hydrogen, which is then fed into fuel cells to produce electricity. The scientists estimate that one day's "output" of animal waste from a typical Japanese farm will produce enough energy to power a home for three days.

* Disposable diapers. In 2007 the British engineering firm AMEC announced it was building a plant in Quebec, Canada, that will use a heating process called pyrolysis to convert the diapers (and their contents) into a mix of synthetic diesel fuel, methane gas, and "carbon-rich char." When the plant is up and running it is expected to convert 30,000 tons of dirty diapers -about a quarter of all the diapers used each year in Quebec- into diesel fuel annually.

* "Turkey waste." For several years a company called Changing World Technologies operated a plant on Carthage, Missouri, that converted the waste from a Butterball Turkey slaughterhouse (beaks, bones, feathers, guts, etc.) into biodiesel. Capacity: 1,200 tons of turkey parts a week. But neighbors complained about the smell ("just like burning meat"), and in 2009 the company closed the plant and filed for bankruptcy.


The article above was reprinted with permission from the Bathroom Institute's book Uncle John's Heavy Duty Bathroom Reader. Since 1988, the Bathroom Reader Institute has published a series of popular books containing irresistible bits of trivia and obscure yet fascinating facts.

If you like Neatorama, you'll love the Bathroom Reader Institute's books - go ahead and check 'em out!

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