The potential of energy harvesting means there’s nothing to lose

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While low-power, autonomous wireless sensing is clearly the main application for harvested energy today, it is commonly felt that the amount of energy available from existing solutions isn’t impeding its use in others: “We’re beyond the stage where power is that important, we’ve shown it can be done and the fundamental breakthroughs were made years ago,” explained Freeland.

Micropelt’s Habbe agreed: “This is not a true bottleneck, even though there is demand for higher power levels. Higher power levels are usually just a matter of cost, as they can be achieved by combining multiple basic harvester elements, but this premium will go down as volumes grow.”

Here, again, the need for better energy storage was raised, by Habbe: “Here is indeed a gap to fill. A ‘pure’ wireless monitoring sensor simply runs off a capacitor or a perfectly rechargeable small thin film battery, because there is no need for monitoring during the non-operational times of its host. However, if continuous access to, or heartbeat from the sensor is critical, there needs to be a bulk energy storage with considerable capacity, able to sustain operation over multiple weeks without the supply of harvested energy.”

It seems that if wireless sensing is to become ubiquitous, creating and transmitting an unprecedented amount of data continuously, the issue of energy storage is the next challenge faced. Several companies already target harvesting applications with energy storage solutions, such as Cymbet and Infinite Power Solutions, both of which produce energy storage solutions for applications powered by harvested energy.

Roy Freeland pointed out that wireless sensing isn’t always about networking, although it has become synonymous with, say, ZigBee, where mesh networking is the default topology. Wireless sensing nodes will be less dependent on mesh networks, but better energy storage solutions could enable a greater level of networking, which inherently demands more power.

Freeland also sees applications that are less dependent on wireless connectivity; closed control loops that simply need harvested energy to power a microcontroller that must wake occasionally for maintenance, but agrees that energy harvesting will drive ubiquitous computing. To reach the level of ubiquitous sensing that many feel is on the roadmap, energy harvesting coupled with improved energy storage will be fundamental, as Micropelt’s Burkhard Habbe, explained: “Energy harvesting will become pervasive as more autonomous systems need power independent of batteries. In fact, to many of those, energy harvesting will be the key enabler, because it is simply impossible to constantly maintain billions of ‘smart dust’ devices in structures, buildings, machines, production assets, cattle, pets and, lastly, humans.”

Courtesy of EE Times Europe.