The overwhelming majority of the scientific community are in concord regarding anthropogenic climate change. Our contribution to the release of greenhouse gases from burning coal and fossil fuels, factory farming of cattle, as well as the removal of spaces such as wetlands and mangrove forests on the confluence of the rivers and ocean, has contributed measurably to sea level rise and changing weather patterns. As the years progress, there is the greater chance for us to see an increase of sustainable energy practices that will offset the demand for these polluting energy sources.
Without access to other forms of high energy-yield technologies, nuclear for example, the truth is for the foreseeable future, in order to maintain the current level of energy needs - think aeroplanes, locomotives, and sea-faring vessels - we are going to need quick, powerful, cheap forms of fuel in the form of petroleum and natural gas.
This doesn’t mean that we can’t utilize wind, solar, and water. Traditionally, high energy items lose a tremendous amount of their payload to entropy. Think of a light bulb. Incandescent lighting, while giving a pleasing glow, are tremendously inefficient and lose around 95% of their energy output to heat. Sustainable practices use the energy that is resident in the act itself - the shining sun, the blowing wind, the turbulent sea - and take the kinetic energy and use it to power the grid. Of course this also has its costs. Hydroelectric dams are notoriously bad for fish, for example, as turbines can be deadly to birds.
It is with this in mind that I turn our attention to energy reclamation. Energy reclamation uses the same principles as wind, solar and hydro. Think of the Toyota Prius. It is a hybrid car with a battery and a gas tank. When the battery won't cut it for power it uses the gas in the tank. One interesting feature of the Prius is that when the driver breaks, it transfers the kinetic energy of braking back into the battery, thus charging it for when it will be needed again. It is using energy of something that the driver will be doing anyway to feed the power source.
Recently, Portland installed turbines in some pipes that deliver water to the city’s residents. They are put into a spot where water flows downhill and, as such, is fed by gravity. These turbines turn and send the resulting power to the Portland power grid.
We likely are unable to rely solely on this kind of energy source for everything. Imagine, though, if new homes were built with similar technology in place - pressure sensitive plates in the floor, for example - or old homes were retrofitted with this in mind. Again, it might not be feasible to power the grid on this action alone but a many drops into a single bucket will eventually fill the bucket.