Practicality balance

Some industrial applications, like water meters, would have a maximum life span of about 20 years, Buccini said, and could benefit from energy harvesting so that maintenance workers wouldn't have to dig them up and replace batteries. For medical applications, "permanent" likely means two to five years, he said, because beyond that a device would become obsolete or wear out.

Some applications seem like they would be ideal for energy harvesting at first glance, Buccini said, but ultimately are not viable because the product's lifetime won't support the cost associated with the energy harvesting circuitry. For example, people have brought out running shoes with energy harvesting devices that capture energy from the motion of running, Buccini said. But this is not practical because the running shoes themselves will wear out in a matter of months, he said.

"There's a balance somewhere between what is practical and what is not," Buccini said.

Bradow of IPS said energy harvesting will only thrive by serving applications that are not adequately served by existing solutions, such as coin cell and lithium-ion batteries.

"If you can use a coin cell, use it," Bradow said. "If you can use lithium ion, use it. But if your applications is not served by existing solutions" then energy harvesting might be desirable, he said.

A coin cell battery has a limited temperature range, Bradow noted, and cannot be used in extreme temperatures.

"We need to find applications that can bear the cost," said Steve Grady, vice president of marketing at Cymbet Corp., also a supplier of thin film batteries.

Grady said energy harvesting stands to benefit from the stimulus packages being offered by governments around the world. In the U.S., President Obama has pushed for smart grid technology, something energy harvesting might be of use for, Grady noted.

"There's going to be some stimulus money here," Grady said. "I think it's going to help move [energy harvesting] forward."