Radio waves

Can we power the smart home with ambient radio waves?

At CES, we saw Samsung show off a TV remote that draws power from nearby wireless waves, even eliminating the need for a battery. While our own A/V editor Phil Nickinson is skeptical of the prospect, I’m more optimistic about the overall implications.

If Samsung applies this technology on a large scale and includes this remote control in all its televisions from now on, there will be a marked reduction in the number of batteries to be manufactured. This is ultimately good news for the planet and probably saves everyone a few bucks. The amount of power saved from charging these batteries will be pretty minimal, considering TV remotes don’t use a lot of juice to begin with. That said, does the air crackle with enough unseen power to run other low-demand smart home devices?

After all, we are blanketed by more and more overlapping spheres of electromagnetic waves, including Wi-Fi, cellular, FM, and TV. Our appliances are also becoming more and more energy efficient. If we use all that power to send signals, maybe we can get some of the energy back by picking it up on the other side. The idea is not new. Nikola Tesla dreamed of being able to power entire cities with wireless transmission. We are far from being able to do this today, but we already have companies making battery-free electronics thanks to the emerging technology in this field.

How would we use wireless energy harvesting?

The further away you are from the source of a transmission, the less it needs to be harvested. The power we can draw from everyday signal strength is minimal. In theory, you would get less than 0.0001 watts harvesting 2.4 GHz power beyond 1 meter from its source. It’s not much to play with.

Despite these limitations, Wiliot was able to create a full-fledged computer that runs on ambient power. It’s a printed sticker that can detect what’s happening nearby, communicate with other machines, and only costs pennies. These are mainly used for food, retail and medicine to track shipping and storage.

Manufacturers love Atmosic can create Bluetooth 5 chips that operate on ambient energy waves. For example, he was able to power a keyboard and make it communicate without the need to install batteries. A commercially available batteryless keyboard using Atmosic’s chip is already under construction.

For devices in greater demand, we will have to resort to dedicated transmitters and receivers. We have already seen several of them, but their energy efficiency is still in question. Wi-Charge is one of the companies that is getting into this. It relies on targeted infrared bursts to send energy wirelessly. Its transmitter has a consumption of 12 volts, but the receiver can generate 5 V at the maximum at the other end. Meanwhile, Ossia works with Spigen to make a phone case that can act as a wireless power receiver, but beyond a six-foot range, it receives a tenth of what’s transmitted. In that vein, GuRu is working with Motorola to embed a power receiver directly into a phone. Their current best-case scenario has effectiveness dropping below 50% beyond 10ft range. Is it worth installing a transmitter in your home if it’s going to be so inefficient? This may be necessary until we bridge the gap between the available ambient energy and the power demand.

So why aren’t we there yet?

There are several reasons why we have not reached the nirvana of a smart home completely decoupled from the energy grid. For one, the power supply constantly fluctuates. Location and obstacles are obvious X factors. Even for devices that are physically static, atmospheric conditions and time of day can influence the quality of radio wave transmission or reception.

There is also the challenge of standardization. If the transmission devices are not optimized to power the targets, it will be difficult to get this vision off the ground. the AirFuel Alliance trying to get several manufacturers on the same page on this front.

A diagram showing wireless power being sent to a range of desktop devices.

Fortunately, radio frequency collection does not exist in a vacuum. Going back to the Samsung remote example, its main feature was actually to run on solar power. RF harvesting can work alongside a host of other passive energy harvesting techniques, such as thermal and mechanical techniques, to meet the total energy demand. Like Samsung, Disney Research has found use in combining ambient radio energy with solar panels to enable wireless data transfer. As the efficiency of these methods improves and manufacturers begin to add layers of ambient energy harvesting, their need for batteries will gradually decrease. Maybe it won’t completely ditch the batteries, but even if it just means getting by with smaller batteries, it’s still an improvement.

At the consumer level, the amount of power we can get from ambient wireless is still very low and inconsistent. At best, these techniques are only useful for devices that need a small amount of power very occasionally. Beyond TV remotes, it’s easy to imagine having independent radio sensors distributed in the farthest corners of your home to provide continuous humidity and temperature reporting. This could very well expand the data set your smart thermostat works with.

The idea has huge implications for the smart home. Although we are still years away from widespread implementation, we can hope that technology like this exists and that the research focus continues.

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