For a long time, hydropower was considered the original renewable energy resource. In many countries, hydropower represents a high percentage of energy production and an alternative to dirty coal or dangerous nuclear energy. But dams around the world also cause problems. Melinda Smith narrates.
Safe Harbor Water Power Dam is one of the largest non-government hydro plants in the United States. It was built in 1931, as the third main plant on the lower Susquehanna River in Pennsylvania.
Dick Johnson is the engineering Manager at Safe Harbor. "This unit is actually operating right now, the unit is running at full speed, this is a Kaplan turbine, but this is the shaft that we are looking at, the turbine is down below, and there is a cover there to protect the water from coming up here."
Hydropower has been used for centuries, harnessing the power of water flowing downward. That has often meant building dams.
But dams carry a number of drawbacks, including their impact on the environment, high construction cost, and displacement of people when artificial lakes are created.
David Hales, a counsel for sustainability at Worldwatch Institute in Washington, also adds that dams often use the most arable land. "Usually you are going to displace people. In the past 50 years some 40 to 80 million people have been displaced by the building of high dams. Those people become environmental refugees."
Marshall Kaiser, the president and Chief Executive Officer at Safe Harbor, says dams also have a significant impact on fish populations.
"The most notable is blockage of fish passage both upstream and downstream. Here at Safe harbor we have a fish lift for moving fish upstream, primarily in the springtime and then we also have means of getting them safely downstream."
In the U.S., where hydropower represents eight percent of the electricity for the country, there are no plans to build any large new dams in the future. However, there are plans to use more of the existing dams to generate electric power.
Linda Church Ciocci is the Executive Director for the National Hydropower Association. "Hydropower is only on two percent of all the dams of the U.S. That means there is 98 percent of the dams that are currently in the U.S. that have no power generation on them whatsoever. So there is a tremendous growth opportunity there in the existing facilities."
When Safe Harbor Dam was built it was dedicated only to the generation of electricity. The other two dams nearby, like nearly 98,000 other dams in the country, were built only for irrigation, water supply and flood control.
Church Ciocci says, "Even if you look at Hoover, as popular as the Hoover dam is, that dam was first built for water purposes beyond energy. They added energy to help pay for it."
There is another, more unconventional way of generating electricity through waterpower.
Trey Taylor is the co-founder and president of Verdant Power, a new project of underwater turbines that look like wind power turbines but work with underwater currents. "It has been tested extensively in Pakistan, Chesapeake Bay and in New York's East River. As a result of those test which exceeded our expectations, we are putting the world's first field of underwater turbines in New York City."
Taylor says the potential for the new technology in rivers and oceans around the world is extensive. Just in the U.S. the interest is increasing rapidly.
Taylor says one of the advantages is that it doesn't damage marine life. "There is lots of room to swim around, they can go through, not a problem. It would be like us walking through a revolving door."
Taylor says his major focus is in the developing world. His company is now looking at remote villages that run on polluting and expensive diesel generators. "Right now we have a team in Brazil, examining the Amazon basin. The Brazilian government is very interested in this types of technologies for the rural electrification of Brazil."
However, experts agree that while the underwater turbines are good, they could never replace the power capability of a dam or its durability. Marshall Kaiser, with Safe Harbor Dam, says, "At the end of our license we will be 100 years old and we have every expectation to be re-licensed another 30 years, and another 30, and 30 more."
Well over half of the planet is water and the use of tides and currents for the production of electricity could be endlessly renewable. The use of dams will remain more controversial.