|How ultra low power wireless networks and energy harvesting are going to make our planet a better place to live.|
By Cees Links, GreenPeak Technologies
Increasingly, we rely on networks of sensors and controllers to make our lives more convenient. Sensors in the home can help control temperature – sensors in an office building can help maintain security and ensure that lights are turned off when there are no humans present. Even our remote controls that we use to turn on our TVs and home entertainment systems are essentially sense- and control elements. In industrial and warehouse locations, wireless sensors are mounted in locations that cannot be easily wired or are inaccessible. Out in the fields, farms are using wireless sensors to monitor soil humidity and conditions. In many offices, thousands of battery powered security sensors are attached to doors and windows for security and access purposes.
The common denominator for many of these common applications are batteries. Batteries - that need to be changed or recharged when they run out of power. Batteries with toxic chemicals and heavy metals can pollute our environment during the manufacturing process as well as when they are disposed of.
The solution has two components and both are happening now.
First, energy-harvesting technologies are becoming more efficient and more affordable. Energy harvesting is a technology whereby energy is gathered from the environment around us. The most common and well-known energy harvesting technology is the solar cell but there are many others that are emerging.
Scientists have discovered that it is possible to get energy from noise, vibration and movement. Power can be generated from the difference between internal and external temperatures. One day soon, it is possible we will see personal mobile health monitoring networks that are powered by the patient’s own body temperature and their daily activities and movements. Researchers are currently developing ways to extract energy from plants and use it to help power a network of sensors and transmitters. These could be used to monitor weather and soil conditions for agriculture, help predict and prevent forest fires, as well as power home sensor products.
Or even more advanced: in many busy offices, there is enough energy bouncing of the windows from the traffic poise outside or the employee’s activities inside including their voices, to run a network of sensors – for security, for environmental monitoring or for simply turning on and off lights as employees enter and leave rooms.
Energy harvesting (or scavenging) is an exciting technology development that could slash our battery addiction. Instead of relying on batteries or even power from the grid this next generation of wireless devices can be powered by energy that is available in the environment. Unfortunately, energy harvesting is still not ready for prime time. Aside from solar cells, no cheap and high volume solutions are in sight. So far, solar cells are the only energy harvesters that are being produced in high volume and at the low cost required by sense and control networks. However, to overcome solar’s “dark shortcomings”, small batteries are still required to store power during dark times.
Low Power Wireless Networks
The second technology development is the emergence of a new generation of ultra low power wireless networks that can be powered either by the low currents generated by energy harvesting or, because of their low power draw, can function for years on a single small cell battery. Based on the IEEE 802.15.4 wireless standard (comparable to Wi-Fi but dedicated for sense- and control networks because of requiring much lower power), these ultra low power networks are targeted to applications that require reliable connections but do not need a lot of bandwidth.
One simple application is using human finger power generated by simply flicking a switch or turning a dial to wirelessly activate a light across the room. These also include medical applications where info about body temperature and heart rate need to be transmitted every few minutes, security networks which need to indicate whether a door or window is open or closed, home automation systems where information to control air conditioners and heating needs to be sent every five minutes or so, or applications that require controlling other machines and devices. For example, at CES, GreenPeak Technologies rolled out several remote control designs for consumer electronics that can function for 15 YEARS on a single cell battery.
By using a wireless mesh network architecture, the information can be relayed from one wireless sensor unit to another until it reaches the central router or controller, thereby extending the range. The mesh network also allows for changes in the network. For example, if a sensor is located on the far side of a facility and a large truck is temporarily parked between it and the main controller, the signal can bounce to other sensors in the facility, around the obstruction, ensuring that the messages get delivered.
By using energy harvesting and ultra low power wireless mesh networks, our world can become a greener place.
Eliminating all batteries and their toxic chemicals is not yet a reality, but with every passing day, as the technology matures and costs drop, this dream of No Batteries Needed is coming every closer.
Cees Links is CEO and founder of GreenPeak Technologies, based in Utrecht, The Netherlands. He has prior experience in wireless networks at NCR Computers, Lucent Technologies and Agere Systems and was involved in establishing the IEEE 802.11 standard,,the Wi-Fi Alliance, and IEEE 802.15 standardization committee. Cees holds a Masters degree in Applied Mathematics and a Bachelors degree in Electrical Engineering from the Twente University of Technology in Enschede, The Netherlands.