Energy is being broadcast all around us from a wide variety of sources in urban lives. We're all familiar with classic AM and FM radio waves, and terrestrial TV broadcasts, all of which we pick up using antennae. But then there's also Wi-Fi and mobile network broadcasts bouncing around, and even satellites from above beaming down wide-ranging broadcasts, which satellite dishes carefully collect, amplify, and decode.
Many techniques have been tried to harvest this tiny amount of energy in the air around us, but the problem has always been that it's too small for anything useful. A technology by UK-based Drayson Technologies called Freevolt may solve this, by turning radio waves into usable electricity to charge low-power electronic devices, such as those found in the Internet of Things, sensors, beacons and wearables. The technology comprises a multi-band antenna and a rectifier, which can absorb energy from multiple RF bands.
Drayson Technologies, which was spun out of Imperial College and has the UK's former Minister of Science Lord Drayson at the helm, has proved this works, by using Freevolt's technology to power a proof-of-concept IoT air pollution sensor called CleanSpace. The CleanSpace Tag offers a personal, continuously-running carbon monoxide monitor that sends data back to your smartphone via Bluetooth.The battery never needs to be changed, nor does it ever need to be plugged in.
It's proof that Freevolt's technology works, and it uses existing radio frequency sources, so it doesn't involve any regulations for approval. It's unlikely to be viable for use outside of busy urban areas, but with urbanisation continuing at pace, that doesn't appear to be a significant issue.
One genuine complication for Drayson is that this technology was announced in 2015. While the company has successfully raised close to 40 million GBP in funding in four rounds over four years, it appears to be making more progress in other areas, including health technologies. Drayson, on their Freevolt site, encourages makers and developers to get involved and pick up Freevolt technology for their own devices, but there's not a lot more information out there on how Freevolt has worked with other companies - if any. That may mean the technology is just too niche.
In any case, reducing the need for use and constant replacement of small batteries in a huge number of low-power devices would be a big win for humanity, reducing waste, reducing the use of precious non-renewables, and preventing harmful and toxic chemicals leaching into landfill.