"In some cases, you may be only harvesting a microwatt or so," said David Freeman, chief technologist in the power supply solutions group at Texas Instruments. "If your device requires a microwatt, you aren't doing anything for anybody."
For Texas Instruments, the solution is to make the devices that use less electricity as well as to make harvesters more efficient.
"It's only within the last three, four or five years that the [harvesters] reported enough electricity to be useful and the energy of the devices were low enough to work," Freeman said.
One potential use for harvesters is building sensors that can monitor air quality. Operators can wirelessly collect that information to efficiently heat or cool their spaces. "The target for most of these applications is 'peel-and-stick,'" explained Freeman, noting that the best location for a sensor may be far away from any electrical wiring. Such locations may also be hard to get to, so changing a battery frequently would be too inconvenient, making them ideal uses for harvesters.
To this end, the company is making integrated circuits and microprocessors that need much less energy.
"Every generation uses less power than the generation before," Freeman said. "As we continue to push the power down needed by these devices, then it makes the harvesting piece more practical."
According to Freeman, the dominant harvesting technology is small photovoltaic panels, since vibrational and radio harvesters don't yet capture enough power to run both the sensor and the transmitter. The company recently made a prototype wireless keyboard that runs on indoor lighting with a battery life that matches the operating life of the device, roughly three to five years. In addition, Texas Instruments is developing sensors to monitor industrial equipment and roadways, where the regular movement frequencies may be more suited to vibrational harvesters.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500