Daily Video

September 16, 2013

Can Coastal Tides Power America?


Last summer the Ocean Renewable Power Company (ORPC) installed an underwater turbine in the bay off Eastport, Maine, the Eastern-most city in the United States. The turbine turns tides into clean, renewable energy.

“Tides are totally predictable, we’ve known for centuries when the tides are comin’ and goin’,” said ORPC CEO Chris Sauer. “We can tell you on– you know, this day, 20 years from now– at this moment, how much electricity we’ll be generating.”

Currently, power generated by water comes almost entirely from dams, accounting for about 7 percent of the U.S.’s electricity needs. However, the U.S. Department of Energy estimates this number will more than double by the year 2030, to 15 percent.

The turbine has raised concerns about the impact on fish and marine mammals, especially since Eastport’s economy depends on the water. To combat these fears, Sauer said, “We do extensive monitoring, and the bottom line is that there is no known– impacts– to the marine environment.”

Local residents back up his claims, saying that the $21 million dollar project has been an overall boon for the small town economy.

“They’ve come in and they’ve hired people,” said Eastport resident David Marang, who helps operate salmon farms in the area. “It’s like, you’ve got to take 5 jobs in Eastport would be equal to 50 jobs in a city like Bangor, Maine. You know, every job counts around here.”

Warm up questions
  1. What do you know about sustainable energy sources? Can you name three? How are they different from non-sustainable energy resources like fossil fuels? Be specific.
  2. What is a turbine?
    • Answer – A turbine, from the Greek “τύρβη” (“turbulance”), is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and waterwheels. Source: Wikipedia
  3. In what ways do non-sustainable energy resources create a negative effect on the environment? If they are not good for the environment, why do we use them?
Discussion questions
  1. Can you explain how an underwater turbine using the consistent change in tide could produce energy? Hint: Think of other turbine sources of energy like wind mills and waterwheels.
  2. What would be a good way to evaluate if there is any effect on the environment from the underwater turbine?
  3. What role do you see renewable energy sources playing in the future of energy policy for the United States and the world? Do you see it changing the role that energy from oil or coal (non-renewable resources) will play?
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