Hydropower conjures images of massive, landscape-shattering dams, such as the Three Gorges on upper tributaries of the Yangtze River in China. Large hydroelectric dams produce enormous amounts of electricity, but they also swallow up vast swaths of natural and human habitat. They impact water movement and quality, sediment patterns, and fish migration.
Smaller in-stream turbines are different. Placed within a free-flowing river or stream, they capture water’s kinetic energy without creating a reservoir and its repercussions. The underwater analogue to wind turbines, their blades rotate as water moves past, generating relatively continuous electricity. No barriers, diversions, or storage are required, only limited structural support. No emissions ensue.
In remote communities from Alaska to Nepal, this technology is expanding electrification and replacing expensive and dirty diesel generators. In urban environments, in-stream turbines can be placed within city water mains (called conduit hydropower).
As in-stream hydro grows, it is important to note that not all “run-of-river” projects actually let the river run. Some have diverted waterways, caused floods, and impeded fish migration. Careful design and installation can ensure clean energy that is also ecologically sound.
Technical summaries for each solution will be available May 1, 2017.