Energy for free: harvesting from RF waves

Why energy harvesting RF waves could benefit the Internet of Things

We have posted before about the exciting potential benefits of so-called energy scavenging, or energy harvesting, and how the approach offers efficiencies and the ability to power small, low-energy devices.

We were interested, then, to see the recent launch of a new product called Freevolt, which harvests the energy from ambient radio frequency (RF) waves.

The brainchild of Drayson Technologies, owned by Lord Drayson, it is envisioned that Freevolt could be used to power low energy devices such as motion sensors, smoke alarms and wearable intelligent devices. It is due to first be employed to run air quality tags that will be used to transmit data on carbon monoxide levels in the atmosphere to a mobile phone app called CleanSpace.

Energy harvesting from RF waves is interesting because in recent times we have seen an explosion in the growth of wireless communications and radio transmitters for mobile phones, Wi-Fi services and short-range technologies like Bluetooth. This means there is a potentially large amount of sources of ‘free’ RF energy to draw on. And because they rely on radio waves rather than another source like light photons, they don’t have to be angled in a specific direction in order to function, like solar panels do. This also means they can be hidden from sight and therefore be less obtrusive.

While the concept of drawing on RF waves for power is not new, using them to run transmitters is. This latest innovation makes them appealing from the standpoint of the Internet of Things (IoT) – a much hyped trend towards an ever-growing network of small devices that are equipped with sensors to wirelessly transmit data. It is estimated there are already billions of these devices worldwide – a number that will only grow.

One challenge facing engineers when it comes to the IOT has been how to power these devices that are expected to emerge. Many, like water meters, air quality readers and light sensors, tend to be in hard-to-reach places. The sheer number of devices means replacing batteries in every one is prohibitively expensive and physically impossible. Some are small too small to take batteries. Being able to draw on RF waves could provide a valuable source of power.

Of course, there are challenges in using RF for power. RF tends to be concentrated in urban areas where its use is more common and harvesting RF will only generate small amounts of energy – but Drayson says the technology will scale.

There are also concerns that any concerted effort to draw from ambient RF waves will degrade the original signal. Drayson refutes this.

We look forward to following this technology and its development.


To find out more about our mechanical design & engineering services, call us now on Tel: +44 (0)1277 261066 or email us at info@warleydesign.co.uk


Contact us

Call us now on
+44 (0)1277 261066 or
Email us