We waste lots of energy. Factories, refineries, warehouses, offices and our homes are all incredibly inefficient when it comes to energy usage and monitoring.  However, by using the next generation of ZigBee based wireless sensor networks, not only can we greatly minimize this wasted energy, we can also reduce the amount of energy required to actually operate these networks. Until now, wires and cables for power and connectivity have limited the widespread adoption of sensor networks by making them difficult and expensive to install and maintain.

Battery powered wireless networks can simplify installation and reduce cost. But their high power consumption and the corresponding need for regular battery replacement has made wireless networks difficult and costly to maintain. Nobody wants to replace hundreds or thousands of window sensor batteries in a large building on a regular basis. On top of that, the manufacture, use and disposal of batteries is harmful for the environment. Open up a battery and what do you find inside – heavy metals and toxic chemicals.

The promise of wireless sensor networks can only be fully realized when the wiring for BOTH the data communication and the power supply is eliminated. Doing so requires a true battery-free wireless solution, one that can utilize energy harvested directly from the environment. Indeed, companies are creating solutions based on ultra-low-power ZigBee-based communication technologies that can utilize environmental energy sources such as light, motion and vibration. This technology, employing on-board power management circuits and software to monitor energy harvesters and optimize the use of harvested energy, enables sensors to operate reliably in a battery-free environment.

Ultimately, battery-free operation is a key step in paving the way for truly green systems that do not adversely impact the environment. This environmentally-friendly approach can also extend the reach of sensing technology to distant and inhospitable climates and regions.

For example, it is now possible to control forest wildfires by building a network of predictive and fire sensors (using moisture, temperature, and fire alert sensors), connected by a GreenPeak low power routing (LPR) sensing network, all powered by Voltree energy harvesting. Voltree harvests metabolic energy from trees and converts it to useable electricity, in sufficient amounts to power a wireless mesh sensor network.  Voltree’s weather resistant “bio-energy converter” power module parasitically harvests metabolic energy from any large plant without harming it with a useful lifetime of the device that is only limited by the lifetime of the host.

With the proper design and dimensioning of this type of network, forest wildfires can be quickly identified over a very large wilderness area. Instead of having to wait for a fire to grow big enough to be noticed by human monitors, by using energy harvesting powered remote sensors in a ZigBee based wireless mesh network, it is now possible to quickly and efficiently respond to small forest fires before they turn into major environmental disasters.

Another good example of how wireless sensor networks could protect our environment is via a network of sensors for leak detection in a remote oil pipeline. Retrofitting a cable to accommodate thousands of standard wired sensors spread out over hundreds of miles of pipeline is very financially challenging even given the enormous environmental risk associated with oil leaks. However, a wireless sensor network equipped with energy harvesters is fairly inexpensive and straightforward to install. No batteries, no power lines, no network cables.

In order to enhance the network’s reliability and ease of use, it makes sense to utilize mesh technology that enables each wireless sensor and actuator device. By using integrated mesh software, each device can then act as a repeater for the other wireless devices in the network. The sensor nodes form a mesh network by sending messages through intermediate nodes from source to destination. This approach enables the network to span larger distances (even when individual nodes can only see a local area of the network), allowing site-wide wireless coverage throughout a facility without the need for dedicated base stations or routers.

This kind of self-organizing, self-healing network streamlines the installation and day-to-day operation. Once a sensor node is powered, it automatically links to the wireless network. This 'plug and play' approach enables every technician to install a system without the need for the sophisticated radio communication training and real world experience often required to set up wireless networks utilizing routers and base stations.

The self-healing nature of this technology also makes it easier to adapt the network to changing office layouts and designs, enabling nodes to automatically find alternative communication routes when the signal quality decreases or building infrastructure changes. If a device fails, the signal is then routed through the other devices in the network.

By combining these two emerging technologies – wireless sensor networks with energy harvesting, we are approaching a “greener” world where energy is conserved, where people don’t need to maintain remote sensors and change batteries, and where the power we need is harvested from the very environment around us.