A portable power plant that provides drinking water for disaster recovery
20 October 2010—In the immediate aftermath of the Haiti earthquake, most survivors lacked three essential things: potable water, power for lights and cooking, and communications networks to tell the outside world what their needs were.
A Hopewell, N.J., company called The Essential Element aims to provide all three with a mobile device that it says purifies more than 87 000 liters of water a day. The device will simultaneously create hydrogen for running an onboard fuel cell or for burning in a separate camp-style cooking stove. The unit also has wall sockets that can be used to charge cellphones and run other electronics.
Best of all, says Michael Strizki, The Essential Element’s chief technology officer, the system, called the Hydra, gets all its power from the sun. The Hydra’s 3.65- by 2.74-meter polycrystalline silicon solar panel array, which Strizki says is 8 percent efficient, generates 2.88 kilowatts. According to Strizki, that is enough to do the following: power a 900-watt pump that draws water to and through the unit’s self-cleaning filtration device, top off a bank of lead-acid gel batteries capable of storing 900 ampere-hours, and run an electrolyzer that splits enough water to fill a 0.37-cubic-meter propane tank with hydrogen pressurized to 140 000 kilograms per square meter.
The hydrogen stored during the day is consumed by a fuel cell to power the pump and water purifier at night. The electricity from the fuel cell and the photovoltaic panels, which sit atop a 4.9-meter-long wheeled trailer, can also power other gadgets and communications gear through 110 volts or 230 V AC and 12 V DC sockets in the trailer.
Strizki notes the obvious benefits of drawing power from the sun instead of the fossil fuels most generators use: “Fuel is expensive, heavy, and has the potential to leave behind a mess. Plus, you have to work out the logistics of delivering it to places where there’s no existing infrastructure.” With the Hydra, he says, your fuel is free. Full batteries and hydrogen tanks weigh barely more than when they’re tapped out, and when the crisis is over, the solar array can be folded down and the trailer carted away, leaving behind no sign of its presence.
Because the unit was created to operate in inhospitable places where technicians are likely to be busy responding to crises, it was designed to be self-maintaining. For example, the filtration system, which has dual filtering membranes, is smart enough to know when the membranes are becoming too clogged with contaminants to be effective. It stops pumping dirty water through one membrane and back-flushes it while the other remains in operation.
“One of the best things about the Hydra is that it’s scalable,” says Strizki. If an area being served requires more power than can be gleaned from the sun by the solar array native to the unit, photovoltaic mats can be plugged in that yield a kilowatt for every 14 square meters unfurled, providing generating capacity limited only by the room available to lay them out.
“Being your own power plant is a distinct advantage, especially in underdeveloped countries where space is not an issue but electricity is,” says Strizki. Though the Hydra’s fuel cell and hydrogen tanks add a new wrinkle, this unit isn’t the only game in town. The Spectra Solar Fresh Water System 20000 from Spectra Watermakers of San Rafael, Calif., cleans 20 000 liters of water a day and also boasts generating capacity. In addition to its solar arrays, which generate up to 825 W, it has a wind turbine that can deliver 1000 W. Because the filtration system requires about 900 W to operate, nearly a kilowatt is available for powering other devices and for charging the 200-Ah battery Spectra says can keep the system running all night and into the next day if it’s not sunny.
What remains to be seen is whether The Essential Element’s higher-capacity purifier, which sells for US $99 500 (compared with about $75 000 for Spectra’s device) can elbow its way into the market.
By Willie D. Jones / October 2010 /IEEE