Power Scavengers

The market for energy-harvesting products powers up

Every 2 weeks the founder and chief technology officer of MicroGen Systems, a developer of energy-harvesting technologies, drives about 6 hours from the company’s Ithaca, N.Y., headquarters to the Boston area to see his son. As he heads down Interstate 90, Robert Andosca doesn’t let the radio interfere with the hum of the road and his own thoughts.

“All I do is think,” Andosca said. “So, I’m just thinking and thinking about these problems and I’ve come up with so many ideas.”

The “problems” have to do with the bumps and vibrations endured by his tires every mile he drives. There is a great deal of energy in all that punishment his wheels endure; he is looking for a way to scavenge and harness it.

Andosca predicts that by 2016 his company will be selling an energy solution for MEMS-based systems for monitoring tire pressure. He hopes to latch onto the growing, government-mandate-fueled market for tire-pressure-monitoring systems (TPMS) and a growing need to find a way to power the tiny devices.

A 1.5-cu.-mm intraocular pressure sensor to aid glaucoma patients developed by the University of Michigan is powered by harvesting light that enters the eye through the cornea. The IOP contains an integrated solar cell, thin-film Li battery, MEMS capacitive sensor, wireless transceiver and ICs vertically assembled in a biocompatible glass housing. Image courtesy University of Michigan.

Tires will be the driver that will allow MicroGen to produce the volume necessary—about 50 million units per year—to eventually sell each energy-harvesting unit for $1. That, Andosca said, will open up the company’s energy-harvesting products to other applications and markets.

According to market research firm IDTechEx, the market for energy harvesting and storage is a potentially lucrative one for companies that can meet the various challenges involved in gathering and using power from the physical environment.

IDTechEx researchers Peter Harrop and Raghu Das write that energy-harvester sales are expected to reach $18 million in 2012 for wireless sensor applications alone. That number is expected to climb to $4 billion in 2021.

MicroGen’s piezoelectric harvesters specialize in converting vibration generated by everything from tires to clothes dryers into power that can be harnessed and used for other purposes. According to Andosca, MicroGen is in discussions with a major appliance company regarding the product.

But vibration is not the only source of ambient energy. Other types of devices include those that harvest radio-frequency (RF) signals from dedicated transmitters or ambient sources such as mobile phones; thermal energy, or heat, generated by differences in temperature between an object and the ambient air; and photovoltaic approaches that convert ambient natural and artificial light into electricity.

While these methods of harvesting energy are not new, the market for them is expected to explode.

Driving growth is the need and popularity of “green” technologies that save energy. Another factor is technological innovation that has improved the ability of devices to collect and translate ambient energy into usable power, along with a push for further integration of “connected” objects and ubiquitous computing, typically referred to as “the Internet of things.”

The IoT will fail to reach its full potential if ambient energy can’t be reliably and continuously transformed into power. Always-connected objects can never run out of energy.

Harvesting partnerships

An energy-harvesting device alone is not useful without the support of other elements. These include a microcontroller, a power-storage unit (battery or ultracapacitor) and the ability to receive information about when and how to use that energy.

That is why more energy-harvesting partnerships are being formed among companies that specialize in one area or another. “It’s almost harder to find somebody who’s not working with somebody else,” said Randy Frank, president of Randy Frank & Associates Ltd., a Scottsdale, Ariz., marketing firm specializing in technology communications.

“One might specialize in microcontrollers, another in batteries or ultracapacitors for storage and another in power management,” Frank continued. “There’s a kind of mix-and-match going on of companies and technologies looking to complement one another in managing power from harvested energy.”

Cymbet Corp. is one company that offers products designed to manage harvested energy. The Elk River, Minn.-based company produces the EnerChip, a 1mm³, solid-state power-management system that gathers, converts, stores and manages virtually all the energy output by harvesting devices such as solar cells and thermoelectric generators.

“Every joule is critical; every microjoule is critical,” said Steven Grady, vice president of marketing at Cymbet.

Salvaging every microjoule is not an easy task. For example, Grady points to an intraocular pressure sensor designed by researchers at the University of Michigan that incorporates Cymbet’s EnerChip (see photo on page 34). The device will eventually be used to help glaucoma patients. The MEMS-based pressure sensor contains a microprocessor, solar cell and wireless transceiver in a device that is a mere 1.5mm × 2mm.

Designers of this tiny device face several challenges, including converting energy from the solar cell. The company has achieved a conversion rate of about 22 percent, Grady said. The next step is taking the energy converted by the transducer and making it accessible to the system, which creates all sorts of opportunities for energy to be lost. Since light sources are variable, energy storage has to be close to 100 percent. Any power leakage would render the unit almost useless.

How a system handles the small amount of energy harvested is the “secret sauce” most energy-harvesting designers keep close to their vests. But the payoff is potentially huge for those companies able to bring highly efficient harvesters to market, because the demand for batteries that never need replacing is expected to surge.

There are several key markets for energy-harvesting devices, including implanted medical devices, where it isn’t possible to change the battery; military applications, where it is dangerous to do so; energy and lighting controls; and freestanding security devices.

Consumer products, Grady said, are still not much of a market because having to change batteries is not a drawback with most products.

Growing trend

Tim Bradow, vice president of marketing for one of Cymbet’s competitors, Infinite Power Solutions (IPS), Littleton, Colo., recalled a day in 2007 when he stood in front of a group of 400 investors at a summit and bragged that IPS had developed an infinitely rechargeable, solid-state battery able to collect ambient energy and power an electronic device for decades.

“They almost laughed me off the stage,” Bradow said. “There were hecklers in the crowd, and there were hecklers in the investment panel in the front.”

About 5 years later, energy-harvesting symposiums are held around the globe and the attendees don’t laugh at pronouncements such as Bradow’s.

Like Cymbet, IPS specializes in managing the trickle of power gathered by energy harvesters. “You trickle that energy in, and you blast it out,” Bradow said. IPS works closely with Maxim integrated semiconductor products to boost low-voltage energy output by photovoltaic or thermoelectric harvesters.

According to Bradow, IPS accomplishes this task by making its solid-state batteries from an inorganic compound that does not eat away at the battery as does the “chemical stew” in lithium-ion or nickel-cadmium batteries. The company uses lithium-phosphorus oxynitride, or LiPON.

Bradow is excited about the prospects for energy harvesting as they apply to distributed wireless sensors. With a new wireless standard, Bluetooth 4.0, replacing disparate older versions, soon everybody’s handheld devices will become a “gateway” to communicate with sensors everywhere. (This leads to the kind of ubiquitous computing that has been “around the corner” for at least a decade.)

Bradow cited the example of a child wearing a bandage that can monitor temperature and other vital signs and transmit that data to a doctor’s mobile phone. However, what is being harvested from the ambient environment is not enough power to charge the cell phone itself.

A Thinergy micro-energy cell from Infinite Power Solutions. The paper-thin, solid-state, rechargeable energy-storage device can be used with all forms of ambient energy-harvesting techniques for recharging, including solar, thermal, RF, magnetic and vibratory. Image courtesy Infinite Power Solutions.

Harry Ostaffe, vice president of marketing and business development at Powercast, a Pittsburgh-based company that specializes in RF harvesting for sensor applications, said one of the most-difficult parts of his job is explaining to potential customers that they cannot use ambient RF energy to charge their laptops or cell phones. What RF harvesting does is add functionality to otherwise “dumb” RFID tags. The technology also is suitable for “trickle charging” batteries in items that might spend months or years in storage.

One day, Powercast’s technology also could power ePaper displays at supermarkets that display prices or other text.

“We certainly hope to see an installed base in OEM designs and actual deployment of our technology in millions of units,” Ostaffe said. “With our new chipset, the total material cost to implement our [RF energy-harvesting] technology for 1 million pieces, for example, is less than $2 (per unit).”

Prices like that will make energy harvesting more attractive, especially for energy-efficient lighting and heating applications.

According to Jim O’Callaghan, North American president of Germany-based EnOcean, it’s a challenge to develop a system that is designed from the start with energy efficiency in mind. As an analogy, he said Chevy did not take a standard car, put batteries in it and call it a Volt. Chevy engineers had to rethink the entire concept of how a car is made.

On the road again

On that note, let's return to Microgen and Robert Andosca, driving from Ithaca to Boston, thinking about all the harsh conditions tires are subjected to throughout the U.S. Tire temperatures can range from -40° F in Minnesota to more than 180° F on desert highways in the Southwest.

Then there’s the shock of each bump. It’s not easy to build an energy harvester that can handle that kind of harsh environment. Armed with some new patents dealing with piezoelectric vibrational energy harvesting, MicroGen has begun to solve the problem, according to Andosca.

A Lifetime Power energy-harvesting-development kit from Powercast for battery charging includes a 3w Powercaster transmitter, a P2110 Powerharvester receiver evaluation board (see schematic), battery charging board, Thinergy micro-energy cell evaluation card, TI wireless development tool and other accessories. Illustration courtesy Powercast.

MicroGen’s BOLT-J power generator (the “J” is for “jiggle”) reportedly can harness power from many different types of inputs. In the context of a tire, it absorbs shock and converts it to electricity, capturing energy from a wide spectrum of frequencies. And, he said, it’s small. Ultimately, the device will be installed in a 5mm × 5mm × 5mm box.

“Our overall goal is to completely eliminate the battery,” Andosca said. “We believe we can do that. Our technology is broadband, low-G (G-force, or gravity force, is used to measure acceleration and can measure small changes), can deal with temperature variation, and it’s small, low-cost and able to handle the shocks that a tire experiences. So we meet all the criteria.”

Beyond that, Andosca said, the technology will allow for a cold start. If a car sits idle for a month, there needs to be a way to kick-start the TPMS if it’s being run without a battery. The initial vibration of the engine might be sufficient to get the unit going, though it hasn’t been tested yet.

He added that “major players” in the TPMS market are approaching MicroGen.

“The companies that we’re talking to right now are on an accelerated schedule,” Andosca said. “They want something in cars in 4 years. We will be in cars in 2016. I can guarantee that.” Not only that, he said MicroGen will be “very strongly in the marketplace.” µ

Contributors

Cymbet Corp.
(763) 633-1792
www.cymbet.com/

EnOcean Inc.
www.enocean.com
(801) 943-3215

Randy Frank & Associates Ltd.
(480) 998-1261
www.randyfrank.net

IDTechEx
+44 1256 862163
www.idtechex.com/

Infinite Power Solutions
(303) 749-4800
www.infinitepowersolutions.com

MicroGen Systems Inc.
(617) 447-1876

www.microgensystems.com

Powercast Corp.
(412) 923-4774
www.powercastco.com