Kinetic energy is energy in motion. The world’s waterways brim with it, as gravity draws water across watersheds, through rivulets and creeks, down larger tributaries, and into rivers flowing seaward. For millennia we have harnessed that energy, first to turn waterwheels and power machinery, then, in the nineteenth century, to generate electricity. Today, hydropower conjures images of massive, landscape-shattering dams: the Three Gorges on upper tributaries of the Yangtze River in China, the Hoover on the Colorado River in the United States, and the Itaipu on the Paraná River, between Paraguay and Brazil. To maximize the kinetic energy available for electricity generation, dams use the vertical distance or “head” – water falls from the top of their structures to their base, rushing over turbine blades with high volume and velocity. Hydroelectric dams produce enormous amounts of electricity. But they also swallow up vast swaths or natural and human habitat—while impacting water movement and quality, sediment patterns, and fish migration.

These drawbacks have shifted attention from grand dams to smaller, in-stream turbines that are akin to an updated water-wheel. Placed within a free-flowing river or stream, in-stream turbines can capture hydrokinectic energy without creating a reservoir and its repercussions. The underwater analogue to wind turbines activated by the breeze, their blades rotate as water moves past. No barriers, diversions, or storage are required, only limited structural support, and no emissions ensue. In-stream hydro can produce renewable energy that is ecologically sound. The presence of a submerged apparatus with moving parts will always have some impact on the life of a river or stream, and concerns persist about harming fish populations and impeding their migration. Careful design and installation are of utmost importance.


… From native communities in rural Alaska to rice fields needing irrigation, this technology is being tested and adopted where expensive and dirty diesel generators have been the conventional source of power.


… This subcategory of in-stream technologies is called conduit hydropower.

IMPACT: if in-stream grows to supply 1.7 percent of the world’s electricity by 2050, it can reduce 4 gigatons of carbon dioxide emissions and save $1.8 trillion in energy costs. Communities in remote mountainous areas are among the last regions in need of electrification; in-stream hydro offers them a reliable and economical method of generating electricity. – DRAWDOWN – THE MOST COMPREHENSIVE PLAN EVER PROPOSED TO REVERSE GLOBAL WARMING – EDITED BY PAUL HAWKEN (book excerpt)

Excerpts only, please see source:  Amazon | Website