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Portable Power

February 26, 2010


In yesterday’s post entitled Better Batteries or No Batteries at All, I discussed some of the research being conducted and products being manufactured that generate power in new ways. In that post, I wrote, “The world is becoming more mobile and that mobility is fostered by battery-powered devices of all sorts.” In this post, I would like to discuss a few other ideas that are helping make power more portable. Let’s start with kid power. In 2008, I wrote a post entitled from From Solar Power to Kid Power in which I discussed a team from Brigham Young University that created a playground merry-go-round that “generates enough electricity to charge between 12 and 24 lanterns, depending on how often children play on it.” A team from Harvard University — an all-girl team — has now created a soccer ball that can generate electricity [“Energy-generating sOccket soccer ball scores a goal in off-grid villages,” by Jeff Salton, Gizmag, 8 February 2010]. Salton reports:

“What kid doesn’t like kicking around a soccer ball? Imagine if this fun activity could also provide enough energy to power something useful in a modest off-grid African village, like a reliable light to cook by or an emergency mobile phone. The sOccket is a prototype soccer ball that captures kinetic energy when it is kicked or thrown, stores it in an internal battery and makes that energy available for a myriad of small but useful purposes. In other words, it’s a fun, portable energy-harvesting power source that is designed to take a kicking.”

One only need look at the fervor created by the World Cup to understand the potential that a soccer ball (or football as most non-Americans know it) has for generating small amounts of electricity. How does the sOccket ball do it? Salton explains:

“The sOccket captures kinetic energy through an inductive coil mechanism similar to the nPower PEG that can charge mobile devices by shaking. As the ball is kicked around, a magnet is drawn through a coil which creates a current that is then stored on a battery. This technological wizardry means the sOccket weighs slightly more than a regular 16-oz soccer ball (5-oz more), but the sOccket team say it is anticipating its design will get even lighter. They are also investigating using local materials, meaning product from Africa where the product is targeted.”

In past posts, I’ve noted how important mobile phones have become in Africa. Charging those phones, however, has been a challenge because, as Salton notes, “95 percent of African countries live off-grid with no access to electricity.” As a result, people have gone to great lengths to get their phones charged. Salton continues:

“The girls at sOccket say that people in some developing countries have been known to walk for three hours just to find an outlet from which to charge a mobile phone. With one of the special soccer balls, the team says the power will literally be in the people’s hands. They anticipate 15 minutes of play time equaling roughly three hours of power for an LED light.”

Getting kids to play soccer shouldn’t be much of a challenge; neither should figuring out a number of ways to use the electricity that is generated. The team that developed the sOccket ball wasn’t just thinking about mobile phones when they developed it. Salton explains:

“The sOccket team says it hopes the invention will help prevent house fires caused by kerosene lamps relied on for lighting by more than 1 billion people worldwide. They report that kerosene is not only expensive in many areas but also highly flammable and the smoke has been known to cause respiratory problems in infants and adults.”

Salton raises one big issue that could cause a bit of strife: Who gets to use the power stored in the ball after the game?

“The big issue for sOccket isn’t deciding who kicks the winning goal in a soccer match, but rather who gets to use the power from the ball after the game. To help solve this conundrum, the sOccket team is working within social settings like schools, hospitals and churches, and a recent trip to Kenya has also been beneficial in giving the team a better understanding of individual households’ needs. … Currently the sOccket is still at the prototype stage but the team hopes to have a completed version that can be distributed by the end of 2010.”

In his article, Salton mentioned the nPower PEG, which is another device that generates electrical power from body motion. Most people have seen emergency flashlights that can be powered up by shaking them to generate small amounts of electricity. The nPower PEG works on the same principle [“nPower PEG uses motion to charge mobile devices,” by Noel McKeegan, Gizmag, 7 January 2010]. According to McKeegan, “the 9″ long, 9 ounce device from Tremont Electric works when you are in motion – just plug in your mobile device, place the nPower PEG vertically in your bag or on your hip and go for a walk or run. The kinetic energy from this movement is harvested to deliver charge at the same rate as a wall charger. This translates to an 80% for most devices in an hour of walking according to the company.” Another portable device that generates power using kinetic energy is a charger called the Etive, designed by Kyle Toole [“The Etive kinetic energy charger gives power walking a whole new meaning,” by Jude Garvey, Gizmag, 20 May 2009]. Garvey reports that “with further development, the Etive should be capable of recharging a 2000mAh lithium-Ion battery in about five hours.”


Another, more direct, approach for generating power using human motion has been developed by a company named Easy Energy, Inc. [“YoGen charger uses your energy for its power,” by Jude Garvey, Gizmag, 4 January 2010]. Garvey reports:

“The YoGen charger works a little bit like the friction cord on the back of a talking doll – you simply repeatedly pull the T-handle and the internal alternator starts spinning. This eventually creates enough power to charge the batteries of most small, portable electronic devices. The ergonomic design of YoGen offers extended charging effort with little operator fatigue. Importantly, it provides 100% green energy and mostly charges devices with only a few minutes of pulling and releasing the T-bar.”

A team of scientists from the Georgia Institute of Technology is also working on a way to harness human kinetic movements to generate energy but its approach involves nanotechnology [“New nanogenerator could charge iPods and cell phones with a wave of the hand,” by Darren Quick, Gizmag, 30 March 2009]. Quick reports that the Georgia Tech research team takes kinetic devices to the next level. These new devices would “use simple body movements, the beating of the heart or movement of the wind, and convert the low-frequency vibrations generated into electricity by using zinc oxide (ZnO) nanowires.” Quick continues:

“A major advantage of this new technology is that many nanogenerators can produce electricity continuously and simultaneously. Add to that the potential to reduce the billions of batteries that make their way into landfill annually and the technology sells itself. On the downside, the greatest challenge in developing these nanogenerators is to improve the output voltage and power.”

A team from the Massachusetts Institute of Technology is also drawing power from the human body; but they are using heat rather than kinetic energy [“Researchers harness heat to power electronics,” by Darren Quick, Gizmag, 17 February 2010]. Quick explains:

“Efforts to capture energy from the human body usually focus on harnessing the kinetic energy of the body’s movement. However the human body is also generating energy in the form of heat that could also be used to run low power electronic devices. New energy-scavenging systems under development at MIT could generate electricity just from differences in temperature between the body (or other warm object) and the surrounding air. … The unique aspect of the new devices is their ability to harness differences of just one or two degrees, producing tiny (about 100 microwatts) but nevertheless useful amounts of electricity. While it won’t be enough to recharge your mobile phone, it should be enough to power low power devices, such as biomedical monitoring systems or sensors in remote and inaccessible locations. … The key to the new technology is a control circuit that optimizes the match between the energy output from the thermoelectric material (which generates power from temperature differences) and the storage system connected to it, in this case a storage capacitor. Such a system, for example, could enable 24-hour-a-day monitoring of heart rate, blood sugar or other biomedical data, through a simple device worn on an arm or a leg and powered just by the body’s temperature which, except on a 37 degree C (98.6-degree F) summer day, would almost always be different from the surrounding air). It could also be used to monitor the warm exhaust gases in the flues of a chemical plant, or air quality in the ducts of a heating and ventilation system.”

Not all portable power solutions rely on human inputs because such motion generally doesn’t produce enough power to operate larger mobile devices. For producing larger amounts of stored electricity, solar power seems to be the approach of choice [“Making Solar Power Portable,” by Liz Galst, New York Times, 8 February 2010]. Galst reports:

“Last year, when Jonathan Smith was still the president of Earth911.com, a Web site dedicated to recycling, he said he would often board a plane after a speaking engagement or a day of meetings with a dead cellphone in hand. With limited recharging options available, ‘it was really frustrating,’ he said. ‘Having access to a working port or finding an open plug during layovers at the airport was just too unpredictable.’ Hoping to solve his problem, Mr. Smith bought a portable solar charger he could prop up in the window of a plane. ‘I’d plug it into my phone and when we landed, I was ready to go again.’ The charger meshed well with his environmental values, of course. Still, ‘when I first started using solar to charge my devices,’ he said, ‘it was out of convenience.’ In fact, Mr. Smith is one of a growing number of business travelers who, out of practicality or concern for the environment, use portable renewable energy devices — primarily portable solar panels, but also hand-cranked electricity generators known as dynamos or freeplay devices — to power up their electronics when they work in places that offer little or no access to electricity.”

Smith’s mobile phone battery challenge pales in comparison to challenges faced by researchers in the field far from power grids. Galst explains:

“‘Basically, this technology makes our work possible,’ said John Poulsen, a tropical ecologist who investigates logging’s effects on animal populations in the forests of central Africa. Often, data collection takes Mr. Poulsen as much as 25 miles from the nearest road. ‘The research we do requires being in the forest for two to three weeks at a time. And if we had to go back to the village every two or three days for batteries, we just couldn’t do it,’ he said. Generally speaking, portable renewable energy devices cannot power large equipment, like desktop computers or printers. But they can generate enough electricity to operate laptops, satellite telephones, movie and still cameras, sound-recording equipment, GPS equipment and camp lighting, said Stuart Cody, owner of Automated Media Systems in Allston, Mass. The company customizes portable solar arrays and battery backup systems for business travelers and adventurers. The devices have improved significantly since they were first introduced in the mid-1990s. That was about the time the tree kangaroo conservation program, administered by the Woodland Park Zoo in Seattle, began using portable solar at its field sites in Papua New Guinea. “Initially, we got panels that didn’t work very well,” said Lisa Dabek, the zoo’s director of field conservation. Now, the solar panels used to power laptops, navigation devices and satellite phones ‘are much smaller and much more portable,’ she added. The organization uses this technology for reasons that have as much to do with practicality as with environmental concerns. Fuel-powered generators, Ms. Dabek said, are ‘very heavy. And to hike uphill with them for two days is not really an option.’ Moreover, generators ‘make a lot of noise that would scare away the tree kangaroos.'”

When it comes to mobile solar panels, however, nothing compares to “a low-power sensor system developed at the University of Michigan that is 1,000 times smaller than comparable commercial counterparts” [“Millimeter-scale, energy-harvesting sensor could operate almost perpetually,” by Darren Quick, Gizmag, 9 February 2010]. Quick reports:

“Researchers have developed a solar-powered sensor system that is just nine cubic millimeters in size. It is 1,000 times smaller than comparable commercial counterparts and can harvest energy from its surroundings to operate nearly perpetually. The system could enable new biomedical implants as well as building and bridge-monitoring devices. It could also vastly improve the efficiency and cost of current environmental sensor networks designed to detect movement or track air and water quality. The system’s industry-standard ARM Cortex-M3 processor, solar cells and battery are all contained on its tiny frame, which measures 2.5 x 3.5 x 1mm. The engineers say successful use of an ARM processor – the industry’s most popular 32-bit processor architecture – is an important step toward commercial adoption of this technology. … The sensor spends most of its time in sleep mode, waking briefly every few minutes to take measurements. Its total average power consumption is less than one nanowatt, which is one-billionth of a watt.”

You won’t be recharging your iPhone with this sensor, but, like the other systems that generate small amounts of power discussed above, it could play an important role in health care. Quick concludes:

“The designers are working with doctors on potential medical applications. The system could enable less-invasive ways to monitor pressure changes in the eyes, brain, and in tumors in patients with glaucoma, head trauma, or cancer. In the body, the sensor could conceivably harvest energy from movement or heat, rather than light, the engineers say.”

As I noted at the beginning of this post, the world is becoming more mobile and that mobility demands the ever increasing use of mobile devices that require electrical power. I suspect that we will continue to see a number of breakthroughs in the years to come in both mobile devices and the way we power them.

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