For a lot of people, getting a drink of water on the hottest of days is just not as simple as filling a glass on the faucet. As an alternative, they walk miles to the nearest well. Or they pay massive fractions of their incomes — greater than the average individual in a developed nation pays — to have a distributor truck in water, which may not even be clear. About one in six individuals, as of 2005, could not entry clean water [supply: United Nations]. However nobody can dwell without water, so it’s usually that folks without access to a clear water supply end up drinking water laced with chemicals or populated by disease-inflicting organisms, which might kill youngsters and shorten adults’ lives.
With this in thoughts, it is easy to see why the World Well being Group put access to protected drinking water on its checklist of Millennium Development Objectives, or targets to fulfill by 2015 [supply: WHO]. However can or not it’s finished? Every pocket of people suffering water stress wants an affordable technique that matches the native conditions and life-style. Chlorine tablets and clay pots, boiling and cloth filters, solar barrels and rain barrels, and filter-geared up straws that can be worn on a necklace have all been tried, but some individuals nonetheless lack a way that works for them [sources: EPA, IDE, EAWAG, Vestergaard]. Here’s a trace: He rides a Segway. Dean Kamen, who invented the Segway and several other groundbreaking medical units, has put a decade of work into a water purifier that he calls the “Slingshot.” The identify is a reference to the story of David and Goliath — to Kamen, waterborne disease is a Goliath of an issue, and expertise is the slingshot [supply: Richardson]. Learn on to find out how the purifier works.
The Stirling Generator
Plans for the Slingshot
From the outside, the water purifier appears like a black field. Inside, there’s a system for purifying water that is actually fairly previous and customary. It is about the dimensions of a dormitory refrigerator. Drug firms use the identical methodology to purify water to be used in medicines [supply: MECO]. The U.S. Navy has used the tactic to desalinate drinking water [supply: MECO].
Drug firm and submarine versions aren’t practical for developing international locations, though. Let’s see how it really works. Kamen as soon as ran down a partial listing of what this course of can purify: the ocean; water laced with arsenic, poison, heavy metals, viruses and bacteria; liquid at a chemical waste site; or the contents of a latrine [supply: Comedy Partners]. Remarkably, all it takes is boiling and re-liquefying water at precise temperatures. They’re too big to maneuver and want technicians on call. The Slingshot is less complicated and extra portable.
Kamen’s black field first connects to an electricity supply. Bacteria, viruses, eggs and spores get hit twice: They do not rise with the steam within the evaporator and are pasteurized by the heat within the purifier. Then, it enters an evaporator, where it is heated a bit of more and boils [supply: Pacella]. Already, some contaminants are misplaced. Something that boils at hotter than 212 degrees F (100 degrees C) — stones, dirt, salt — stays within the evaporator and is drained out. Next, you hook it up to a water source by dropping the hose in some water. The dirty water gets sucked into the system, where it warms to its boiling point (212 degrees Fahrenheit or 100 levels Celsius).
Steam rises from the evaporator right into a compressor. The compressor squeezes the steam just a little, raising its temperature a bit above 212 levels F. The steam flows into an outer chamber whose walls are about 212 degrees F, creating another filtering step [source: Pacella]. Any contaminant that boils at colder than 212 levels F, akin to benzene, stays a gasoline and is vented out. Solely pure water condenses on the partitions.
The clear water drips right into a ultimate chamber, ready to be spouted out. Since sizzling water can be awful on a hot day, the machine cools it utilizing a clever technique. But there’s an issue: The water is still scorching. It flows incoming and outgoing streams of water past one another, so dirty water heats to 212 levels F and outgoing water cools to the outside temperature. This heat recycling trick is known as a counter-flow heat exchanger.
Whereas the Slingshot is a robust purifier, there’s a catch. It needs electricity. It’s not a lot electricity, although — about 1 kilowatt, which is a mere espresso-maker’s requirement. Learn on to seek out out what it’s.
But electricity may be onerous to find in places that want clean water. So the materials to run these Stirling engines will be found virtually wherever. You’ll be able to see how they work within the article How Stirling Engines Work. Designs that require heat, as Kamen’s does, can burn almost something, from kerosene to methane from decomposing cow dung. If there is not any electricity grid, the purifier can plug in to a diesel generator, which is what many off-grid hospitals use to energy gear. In cities with an electricity grid, the purifier can plug in to a wall outlet. However within the remote desert or bush, where diesel is impractical, Kamen may suggest his Stirling engine. As a source of cold, they can use air. The heat and chilly broaden and compress a gas to make pistons pump.
Kamen’s Stirling is more than an engine — it’s also a generator. (Engines convert gas to motion, and generators convert motion into electricity.) An extra half allows Kamen’s Stirling engine to produce electricity. The rotor rotates inside a steel coil, which creates a present [source: Van Arsdell]. When the engine’s pistons pump, they flip a magnetic rotor.
When running on the Stirling generator, the Slingshot plugs in to it with a power cord [source: Kamen]. One model of Kamen’s Stirling produces 1 kilowatt — enough to run the water purifier [supply: Kamen].
But the two devices might fit collectively much more harmoniously. There, it might probably do work, heating the incoming water and surrounding the purifier like a jacket, trapping heat inside [source: Kamen]. With help from the generator, the purifier could be much more efficient. The generator occurs to make a whole lot of further heat because it burns fuel — as much as eighty five percent of it does not get used. But when the generator and purifier are connected by a tube, hot air can blow into the purifier.
Stirling engines are exhausting to make because a number of the concepts are tricky to execute, and it is challenging to mass-produce them affordably. However some firms are advertising and marketing Stirling engines, and DEKA (a research and development company based by Kamen) hopes its design will make it even easier [source: WhisperGen].
Now that we know what the Slingshot is and one way it can be powered, let’s look at why it is likely to be interesting to a village in want of clean water. Close by, there is a stream. How would the Slingshot enable you and your group? Unfortunately, your and your neighbors’ outhouses empty into it. Everytime you want potable water, you should stroll six miles (10 kilometers) to a well and lug a small supply of water dwelling in jugs otherwise you drink the stream water and take your chances.
In someday of working stream water by the Slingshot, you’d be capable to make 264.2 gallons (1,000 liters) of unpolluted water [source: Schonfeld]. Since every villager makes use of about 5.3 gallons (20 liters) of water a day for drinking, cooking, and bathing, which is typical in a creating village, one Slingshot could provide enough water to assist the needs of half of the village [source: United Nations]. This sounds nice — however might the village afford it? Each villager could chip in $10 to $20, however that’s greater than every week’s wage in plenty of locations [supply: United Nations]. Extra realistically, some community members would possibly get a loan, buy the Slingshot and then sell clear water to the rest of the village at an inexpensive value (maybe three cents per gallon or one cent per liter) until the machine is paid for [source: Schonfeld].
Ok, so you already know what it’ll value financially, however what else is there to consider? What are the professionals and cons of utilizing the Slingshot?
One convenience of the Slingshot system is that the village would not want an knowledgeable to run the purifier. One other plus is that the water should haven’t any chemical aftertaste thanks to the distillation process. The directions are super easy — you stick the hose in soiled water and press a button. This simplicity makes the system protected to function with little room for human error or mishaps.
While operating the system requires the simple push of a button, you would still have to get water to the purifier. And eventually, the machine’s moving elements might finally break and require servicing or changing, which would cost cash. The purifier is just too heavy for one person to hold, so transferring it might require a bit bit of man- (or girl-) energy. Usually, meaning both carrying dirty water to the purifier or putting the purifier near the soiled water provide.
Read on to search out out what’s on the horizon for the Slingshot. DEKA Analysis and Development is in search of a financer and a manufacturer to assist it make Slingshots. In accordance to 1 report, Kamen approached a number of massive companies and private foundations for financing, with no success [source: Richardson]. By one account, the results had been wonderful [supply: Richardson]. The subsequent step is production.
The corporate is rethinking the best way to market Slingshots, in a single state of affairs, first selling it to industries for industrial distilling to get it into manufacturing. Listed here are the primary few. Kamen has additionally mentioned bodegas in Mexico, imagining regions that may plug the purifier in to a wall outlet however want an inexpensive way to make and distribute clean water [supply: Richardson]. The primary objective nonetheless stays — to get the Slingshot to anybody who needs secure drinking water. Does the Slingshot meet them? The exhibition, which is titled “Design for the other 90 Percent,” covers the topic of design for poor populations [source: Smithsonian]. Martin Fisher, a mechanical engineer who worked on improvement initiatives in Kenya for greater than 17 years, contributed an essay describing his design principles for the poor.
The top want of people who find themselves poor is to generate profits. The machine should assist somebody generate income on the native market.
People who are poor do not lack time and labor, so until they will generate profits from the saved time and labor, they won’t purchase the machine.
A device ought to pay for itself in “farm time” — three to six months.
Successful devices tackle people’s true wants reasonably than what “we” think “they” need.
Fisher provides that if a system will not make somebody a right away profit but will save money, it should not promote for greater than the cost of a chicken at the local market. A rooster, like this gadget, is an inexpensive, occasional luxurious for poor households. But if the gadget prices more, only the center class will buy it, and this group already has cash for its fundamental wants [source: Fisher].
While Fisher’s rules are affordable for a lot of product designs developed for poorer populations — the LifeStraw actually suits some of these criteria — they don’t seem applicable to the Slingshot in that it is a system that may present for a big population, fairly than a person. “March 20, 2008: Dean Kamen.” (7/2/2009) http://www.colbertnation.com/the-colbert-report-movies/164485/march-20-2008/dean-kamen And, while it is easy to agree with Fisher’s assertion that poor people need to earn money, there’s one caveat to contemplate; is it really their “high” need? It’s doubtless many would argue that access to wash drinking water demands top billing.
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