Energy Harvesters, Thin-Film Batteries, Micro-Channel Fuel Cells Start Production
Paula Doe, SEMI, San Jose, www.semi.org -- Semiconductor International, 6/13/2008 8:33:00 AM
The construction industry is starting to replace copper with silicon, and that’s just one of the potentially big applications for wireless electronics, powered by energy harvesting, argued Jeff Shepard, president of the Darnell Group (Corona, Calif.). Darnell forecasts sales of more than 200 million units for energy harvesting and thin-film batteries over the next 24 months, primarily driven by wireless connections and energy harvesting replacing power and signal wiring in buildings. The economics are compelling. Shepard noted the example of a recent warehouse that installed a wireless system instead of traditional copper wiring and saved $70,000 in material cost and a week in installation time. “And that’s using today’s relatively expensive batteries and harvesting technologies that are just starting production,” he said, “before the typical cost reduction of silicon with volume.” Wireless building security and energy management systems are already in use in Europe in droves, he noted.
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| 1. The Torre Espacio in Madrid reportedly cuts its energy usage by 40% with 4200 self-powered wireless light switches, daylight sensors and occupancy sensors. (Source: EnOcean) |
The mechanical movement of pushing a wall switch changes the flux in a coil to generate a very short electrical pulse. That’s enough to send a very low-power radio signal to turn a light on or off, eliminating the need to install wiring. Key is the combination of energy harvesting with very efficient radio design.
Other systems can enable a smart building to sense and adjust light or heat to cut energy usage. Although the company is focusing on the building automation market, EnOcean is also getting calls from folks interested in everything from wireless lighting control for boats to call buttons for aircrafts to automatic transmissions for bicycles.
Advanced Cerametrics Inc. (Lambertville, N.J.), meanwhile, is making strides in the technology of harvesting energy from vibration with its flexible piezoelectric ceramic fibers. The fiber can reportedly be easily produced in volume at low cost, and the long thin cylindrical geometry conveniently maximizes the piezoelectric effect.
The technology has been in limited commercial use for a while in smart tennis rackets and skis, where the fibers sense vibration, harvest the energy from that vibration, and then use that energy to bend the fibers to oppose the vibration. Dampening the vibration allows better edge control of skis on rough snow or higher power tennis shots without elbow damage.
But improvements to the power density are now opening up more potential applications, said Jerry Ruddle, vice president of development, and tests are underway with partners for wireless sensor networks for monitoring the condition of bridges, industrial equipment and aircraft engines. “We’re about to introduce our second-generation standalone harvesting unit that can produce 10× the power per mass, or more than 1 mW at 3.6 V, that charges a 1 mF capacitor in 15 sec,” Ruddle said. The unit measures ~1 × 1 × 6 in.
Flexible thin-film batteries ramp production
Also key to enabling innovative wireless applications are tiny thin-film batteries that can be embedded into tiny spaces, and perhaps continually trickle charge with tiny amounts of harvested energy.
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| 2. Thin-film battery. (Source: IPS) |
“We’re using common thin-film deposition technology, but with foreign materials,” said CTO Bernd Neudecker. “And we need different handling of materials within the chamber and RF-compatible chambers.” But ramping volume production is going to take volume suppliers. “If we’re going to be making 100 million batteries for the Samsungs and Motorolas of the world, we’re going to need the equipment vendors and target manufacturers to do 100 million square inches a year,” he added. “We really need the big boys playing here. It’s up for grabs, folks. Who wants to step up?”
Taking a different approach for its tiny flat battery is Solicore Inc. (Lakeland, Fla.), which uses a polymer matrix electrolyte for the core of its flexible 3 V lithium thin-film battery, which it is producing in volume for the powered card market. The company uses a roll-to-roll process, coating on an electrode material, overcoating the electrode with a polymer electrolyte separator, adding the anode, folding over the sheet to encase the anode, punching out units of the desired size, and laminating them in aluminum foil. “Our capacity is 2 million units per month and we’re now flat out, 24 hours a day and in the midst of expansion,” said CEO David Corey. “We have seen tremendous demand for our Flexion batteries in 2008, and we currently have orders well into 2009. We’re currently expanding to double our capacity to 4 million units per month by the end of 2009.”
Demand is coming from makers of secure cards, which embed the battery into one-time password financial and access cards being deployed worldwide. Corey said the battery has a shelf life of three years and enough capacity to display codes for tens of thousands of transactions. In high volumes, it should cost about $0.75.
Micro-channel approach helps fuel cells find a niche
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| 3. This book-sized 25 W fuel cell uses a MEMS micro-reformer. (Source: Ultracell Corp.) |
UltraCell is moving to automated assembly and testing as it moves toward volume production of its portable, reformed, methanol fuel cells for the military and off-grid users in the $74M manufacturing plant it opened in Dayton, Ohio. UltraCell’s small, lightweight 25 W cells, about the size of a hardback book at 2.7 lbs, reportedly delivers 600 Whr/day, and have passed standard military safety and reliability tests. The units are in use to power equipment ranging from radios to sensors to laptop computers in mobile and remote operations.
Key to the small size is a MEMS-based reformer on a chip, which first converts methanol to hydrogen to allow use of more efficient hydrogen cell technology. Reactive heating elements and micro-channels filled with catalyst particles are patterned on silicon. Methanol and water flowing through the channels are heated to 280°C to react to produce hydrogen, which then passes through a specialty membrane that tolerates impurities.
Also using micro-channels to cut production costs and enable better control of high-temperature reactions is Adaptive Materials, which extrudes tiny ceramic tubes for its solid oxide fuel cell. The high temperature of the solid oxide fuel cell reaction cuts the need for the pricey platinum catalysts of the typical proton-exchange membrane cells, but has typically also made the solid oxide fuel cells too hot to handle and slow to start up. Adaptive Materials said its microtubes solve the problem by isolating the active 700°C reaction area in a small region in the center of the tube, leaving the ends no more than warm to the touch. The company argues the solid oxide technology allows higher-energy density, and said it’s now getting more than 500 W/kg. The cells run on readily available propane.
