Power Plants

Large, distributed networks of sensors are becoming more commonplace to support important applications in digital health, autonomous vehicles, smart homes and factories, environmental monitoring, and precision agriculture. The underlying sensor, processing, and communications technologies have plummeted in price and energy consumption, making large-scale deployments practical for many more use cases than in the past. But despite these technological advancements, these installations are still plagued by a nagging issue — supplying them with power.

This is a problem on two major fronts. In the first case, the deployment of millions, or even billions, of always-on sensors will tax the already overly burdened electrical grid. And perhaps the even more pressing issue is the question of how to physically supply the devices with the power that they need for operation. With such large, widely distributed architectures that may include remote regions, running wires from the electrical grid to each sensing unit is completely impractical. Similarly, the maintenance and expense associated with utilizing battery power is also impractical, not to mention the environmental concerns that would arise.

For these reasons, developers and researchers have experimented extensively with alternative sources of energy, like solar and wind. These technologies certainly have their places, but at nighttime or on a cloudy day, a solar panel is not of much use. Likewise, a wind turbine will not keep the device powered up without a breeze blowing.

A new approach to the problem of supplying power to distributed devices was recently presented by a multi-institutional group led by a researcher at Northeastern University. You may have thought that artificial plants were a bit tacky and only for people that have a knack for killing houseplants, but for this inventive team, these fake plants are the power source of the future. They have developed fake plants that can generate energy from multiple natural sources, rendering them able to supply energy under a wider range of conditions than traditional solutions.

While the researchers’ solution will certainly not cover all conditions, it is a step in the right direction, and the work could be expanded upon in the future. As it presently stands, the fake plant can generate electricity from both wind and rain. To harvest electricity from wind energy, a triboelectric nanogenerator was constructed. This generator is composed of a layer of nylon nanofibers that is sandwiched between layers of Teflon. As the layers are pressed against one another by the force of wind, an electrical current is produced.

In order to harvest energy from falling raindrops, textile droplet-based electricity generators were also built into the system. This generator was also made from Teflon, with waterproofed electrodes made of a conductive fabric. As raindrops strike the electrodes, electricity is produced. It was demonstrated that the triboelectric nanogenerator can produce 252 volts, and the droplet-based electricity generators could generate 113 volts — but only at low levels of current and for short periods of time.

The artificial plants themselves serve more of a purpose than to simply make the generators look visually appealing. The leaves catch the wind and present a larger surface to drops of rain, thereby enhancing the system’s ability to capture energy from these natural sources. This capability was demonstrated by the team in a series of trials in which the plants powered a set of ten LEDs. As the simulated wind blew, or raindrops fell, the lights would turn on. Naturally, this energy could also be used to power sensors or low-power computing units to perform more meaningful tasks.

There is still much more work to be done. Wind and rain, by themselves, cannot provide consistent power. Moreover, the current produced is in the microamp range, which is insufficient for most real-world applications. But with further development, the researchers envision their technology being used for larger systems, or in networks of power plants.