Hydropower: Clean Energy?

"Renewable energy" is an umbrella that covers non-polluting and sustainable forms of power generation, like hydro, wind, solar, geothermal, and biofuel. Of course, by now, we're all aware that coal and oil are being rapidly depleted and causing some serious pollution issues, namely greenhouse gas emissions. But are all renewables completely benign?

Hydropower: You dam a river and integrate turbines into the structure that rotate as water flows over them, thereby creating electricity. The United States has dammed almost every conceivable river in the nation since the early 20th century, not only for power generation but also to re-allocate H2O to water-thirsty communities. No greenhouse gases are emitted: it must be eco-friendly, right? The truth is that the environmental and social impacts of dams can be astounding.

From an economic standpoint, dams cost millions of public dollars to build and can quickly become obsolete, as sediment build-up behind the dam wall is incredibly costly to remove.

Let's talk more about sediment: the flow of soil and nutrients downstream is crucil for the success of ecosystems, particularly agricultural terrain. The ancient Egyptians relied on annual floods to spread nutrients over their farmland. The damming of rivers in modern times has altered this natural pattern and deprived downstream ecosystems of vital nutrients.

Blocking a river creates an enormous pool of water behind the dam--the inundation of miles and miles of land alters once-pristine habitats. Keystone species often found along rivers can be wiped out once their habitat is submerged in water. Aquatic species like salmon that rely on travel to specific locations along the river are particularly effected.