Many of us are familiar with the towering earth and concrete structures holding back large reservoirs of water, and this is the association that we have with hydroelectric power. Large dams with heavy water flows driving the turbines. Harnessing electricity from the flow of water, though, may not require this infrastructure.
When a dam is built it can serve many purposes, but a feature of the dam is that it holds back a large amount of water. This usually creates a reservoir and will flood large portions of land which may or may not be inhabited. The abandoned towns and villages may lie largely intact underwater and have become part of the marine environment.
Of course, with a structure holding back so much water, you have to be careful and certain to make sure that it can withstand the forces. A failure can mean the catastrophic release of water from the reservoir and give the population living downstream from the dam very little warning about the impending flood.
Though there are risks as described above, dams continue to be built and there is very little to worry about when it comes to their safety. However, because of these drawbacks, when looking at a way to use the flow of water to generate electricity, a run-of-the-river plant design may be more acceptable and feasible.
Using minimal invasive infrastructure, a run-of-the-river plant literally uses the existing flow of the river to drive the turbines. A drawback here is that the plant is dependent on how fast the river is flowing, which can vary by season. A dam with reservoir can more precisely control the flow of water through the dam, therefore it may have a higher capacity factor.
Another major consideration in determining how to harness the river’s power is whether or not the river needs to remain navigable. A dam is literally a wall built to block the river, so when a river is vital for transportation of goods and persons, a large dam may not be feasible.
As technology develops so to do we adapt to our own capabilities, but also draw inspiration for new designs because of our limitations. Run-of-the-river plants are an excellent example of engineering ingenuity.