Recent reports are mentioning the development of a battery-free technology to help devices operate without the need for batteries. What exactly is being said, why is it a lot of hype, and why will energy harvesting devices fail to power electronics for the foreseeable future?

What is BFree?

Reports are going around mentioning how a research team have developed a battery-free concept for future electronics that would remove the dependency on batteries. The idea behind the technology is that energy harvesting devices can be used solely to power devices, thereby reducing the amount of e-waste produced by batteries and the mining operations needed to obtain materials such as Lithium.

The newest development refers to a device called the BFree Shield, whose design and construction are available online on GitHub for anyone to view and build. This shield incorporates an ARM Core microcontroller (the MSP430FR59941), various supporting components, I/O, and power circuitry to harvest energy. Once built, the device can be programmed using CircuitPython and enable the development of battery-free devices.

The researchers from Northwestern University and the Delft University of Technology were also in the press for developing a battery-free game boy back in September 2020. The device would utilise solar cells and mechanically operated switches as its source of energy and can allow for infinite play while in use.

Why is BFree nothing but hype?

The idea of energy harvesting devices is nothing new, and they are long sought after for key applications in the IoT and IIoT fields. Power can be tricky to provide in remote locations. Energy harvesters can absorb naturally occurring energy and channel it into powering a device. For example, remote farming sensors in the middle of a field can be connected to solar panels and wind turbines in conjunction with a large capacitor to provide consistent power to the sensor.

In the case of the BFree reports, nothing new has been developed, and the designs simply recycle technology that has already existed for decades. For example, the Game Boy can utilise power from button presses, but the case covered in solar panels somewhat makes the design nothing more than an over-glorified solar-powered console.

In the case of the BFree Shield, it is nothing more than a microcontroller connected to a power circuit utilising a MAX17222 and multiple power source inputs. The BFree design further points out that a large capacitor is used to hold energy stored while the solar cell and other energy harvesting devices provide energy.

To summarise, the BFree Shield is little more than a power converter with a low current microcontroller connected to energy sources that already have existed. Calling the BFree a “revolutionary design” or “Breakthrough” is disingenuous and misleading.

Why will energy harvesters fail in the commercial device industry?

Energy harvesting devices can work and have been proven, but only in applications where power requirements are absolutely minimal. Trying to tap energy from stray Wi-Fi or the small movements from the human body is a difficult feat as these energy sources are minuscule.

However, some may point at the energy harvester that powered the Game Boy, but this was a solar-powered device, and the device was more solar cell than display, making it an impractical device. Furthermore, the vast majority of the power coming from solar cells means that the device would only be practical in bright sunlight.

This leads us to the argument that energy harvesters will not be able to provide power for future smartphones and other portable devices. Small IoT sensors in remote locations can be designed to consume minimal amounts of power, and it is these applications will benefit from energy harvesters. Portable devices, however, are always-on devices, required to compute large amounts of data, display large amounts of information to the user, and perform tasks such as video rendering and streaming.

Energy harvesters could be incorporated into smartwatches, but full-fledged smartphones will never operate with such technology. Considering that solar cells are currently the best form of energy harvesting to date, battery-free devices will continue to fill a niche market of smart buttons and miniature sensors.