The LucidPipe™ Power System
Lucid Energy can turn wastewater into renewable energy with their drainage pipes containing hydroelectric turbines. How cool is that? The idea of putting these turbines in pipes may seem like a no-brainer but there are downsides to it, mainly installation and retrofitting costs.
Regardless, this is an amazing example of how a simple idea can come to fruition through passion, some design thinking, brilliant engineering, and approaching a problem from a different angle. Make free energy from toilet water? Pretty cool stuff.