Researchers who study energy harvesting see energy all around us – we just need to find a way to capture that energy. One of the latest energy harvesting techniques is converting the mechanical energy from falling raindrops into electricity that can be used to power sensors and other electronics devices. Scientists from CEA/Leti-Minatec, an R&D institute in Grenoble, France, specializing in microelectronics, have recently developed a system that recovers the vibration energy from a piezoelectric structure impacted by a falling raindrop. The system works with raindrops ranging in diameter from 1 to 5 mm, and simulations show that it’s possible to recover up to 12 milliwatts from one of the larger “downpour” drops. “Our work could be considered as a good alternative to power systems in raining outdoor environments where solar energy is difficult to exploit,” Thomas Jager told PhysOrg.com. He explained that the system could be used for both mobile outdoor devices as well as indoor power. “For example, we intend to develop remote sensor nodes in cooling towers, but abandoned sensor networks are also one of the foreseen applications for this type of system.” As Jager and coauthors Romain Guigon, Jean-Jacques Chaillout, and Ghislain Despesse explain in a recent issue of Smart Materials and Structures, the physics of how a raindrop impacts a surface is not fully understood. However, to build a rain energy harvesting system, the important part is to estimate the recoverable energy during the impact. When a raindrop impacts a surface, it produces a perfectly inelastic shock.

The amount of energy generated by the impact can then be estimated using a mechanical-electric model. To capture the raindrops’ mechanical energy, the scientists used a PVDF (polyvinylidene fluoride) polymer, a piezoelectric material that converts mechanical energy into electrical energy. When a raindrop impacts the 25-micrometer-thick PVDF, the polymer starts to vibrate. Electrodes embedded in the PVDF are used to recover the electrical charges generated by the vibrations.

View: Full Article | Source: PhysOrg.com

I'm afraid it might be just a drop in the bucket against the current consumption!

There's ALOT of electricity wasted on streetlights. Dosn't matter the time, weather, or how dark it is, the streetlights use the same amount of electricity and produce the same amount of light.

Sensors are used to detect how dark it is and whatnot, and the lights change accordingly. These sensors are a bit expensive though (but nothing a town like Abbotsford couldn't afford) and I think they require electricity to power. Solar panels aren't the best bet because of the lousy weather in B.C.

This might be a great solution, well keep these fall, winter, spring, then a smaller solar (made from that 30x blacker material that I saw a thread about here) for the summer.