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Micro-Power Hydro: An Energy Alternative Whose Time Is Coming

Tiny hydro generators that can fit in a creek offer a low-cost, local way to decentralize the power grid.

Photo Credit: David Herrera


Kansas is not a state that’s known for its water resources. In fact, when European settlers first reached this region, it was a semi-arid, treeless plain of grass. In 1931, when historian Walter Prescott Webb wrote about the settlement of Kansas, and other Great Plains states, he  described “the search for water” as a “continuous and persistent” issue.

It’s not terribly surprising then to learn that Kansas has only a trifling supply of hydroelectric power. Throughout the whole state, the annual mean in production is just 1 megawatt * – enough to power fewer than 800 homes, or roughly 0.01 percent of the Hoover Dam’s nameplate capacity.

But Kansas has the potential for much more. In fact, the state could be getting almost 300 megawatts of electric capacity from water power – enough electricity for 240,000 homes. The key: That potential is only accessible if you’re willing to think local.

Across the United States, changes are afoot that are making smaller-scale energy generation make appealing. One of the major benefits of this localized power is that it enables us to take advantage of renewable resources that were previously out of reach. This is particularly true for hydroelectric power. In fact, without smaller scale generation, hydro doesn’t have much of a future at all.

A dramatic shift

The United States really can’t build many more large-scale hydroelectric dam and reservoir systems. According to the U.S. Geological Survey, there weren’t enough good reservoir locations to supply all of the energy the United States consumes. What’s more, the best spots are  already being used.

Amoskeag Hydro Station, Maryland. Capacity 16 MW. Courtesy Flickr user PSNH

In 2006, though, the Department of Energy (DOE) released a paper that took a second look at the potential for hydro power in the United States. It paid serious attention to places where you could make electricity without building a dam.

These sites identified by the DOE would all have capacities of less than 30 megawatts, with some less than 1 megawatt–in contrast to large hydroelectric dams, which usually have capacities of hundreds and thousands of megawatts. What these new sites lack in size, however, they make up for in numbers. The study found 5,400 sites in forty-nine states where dam-less hydroelectric power could be developed in a practical way. Taken together, the sites represent as much as 18,000 additional megawatts of electric capacity we could be using but currently are not. It’s enough to increase the total U.S. hydroelectric capacity by 50 percent —something that wouldn’t be possible to do if we focused only on developing  more large hydroelectric dams.

This would require a dramatic shift in the way we think about energy. In fact, for the better part of the 20th century, it made much more economic sense to build large power plants, facilities that can serve millions of homes. But that is starting to change.

Limits to centralized plants

Electricity is a commodity and we make it in bulk. More than 95 percent of our electric generation ( pdf) comes from what are called “centralized” power plants ( pdf). These are large facilities–most have hundreds of megawatts of capacity each–and they’re located far away from the people who actually use the electricity they produce. Centralized power plants include those that feed on coal and natural gas, but we make renewable energy this way, as well. In 2009, according to the U.S. Energy Information Agency, 7 percent of our electricity came from hydroelectric power and almost 90 percent of that came centralized hydroelectric power plants ( pdf).

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