Big forecast for technology that harvests energy

Get used to hearing more about the concept of energy harvesting during the next four years.

These are those sometimes modest, often hidden technologies that work to convert ambient energy -- such as the motion of carrying around portable electronic device or even a simple touch -- into a power source, usually stored by rechargeable batteries.

Cleantech analyst firm Pike Research figures that there were about 29.3 million devices shipped in 2010 that were powered by energy harvesting methods. What was shipped last year falls mostly into the category of watches and wireless sensors, but this is changing, the trends suggest. By 2015, Pike Research forecasters believe that annual shipments of devices that rely on energy harvesting will reach 235.4 million units because of adoption in industrial and consumer sectors. The consumer market will account for about 42 percent of those shipments.

Explaining the shifting market dynamics, Pike Research Clint Wheelock said:

"The adoption of energy harvesting technologies is being driven by both convenience and economic factors. As the capabilities and cost of the technology improves, energy harvesting will be an increasingly attractive alternative to traditional batteries for a wide range of consumer and industrial applications."

Energy harvesting will be increasingly relevant for gadgets such as wireless sensors, for mobile electronics devices or for more sophisticated technologies being used in medical or military applications that can't tolerate frequent battery changes. There are several different technologies that are relevant as energy harvesting becomes most common, including photovoltaic (teeny solar cells), thermoelectric (heat), piezoelectric (touch) and electromagnetic. The most dominant force at least initially will be photovoltaic.