Florida Looks to the Sea for Energy

Researchers in Florida look to the ocean for energy.

July 30, 2008 — -- A consortium of Florida universities is about to embark on a bold and ambitious program aimed at realizing an old and elusive goal -- tapping into the restless energy of the world's oceans.

"We're sitting on the edge of what could be a major energy resource," said Susan Skemp, a mechanical engineer who directs the Center for Ocean Energy Technology at Florida Atlantic University, the epicenter of the effort.

About eight billion gallons of sea water flow past the southern tip of Florida every minute as part of the Gulf Stream, a global wonder that has long mystified oceanographers. This underwater river dwarfs all the rivers of the world combined, transporting more than 30 times the total freshwater flow in rivers around the globe.

That amazing force has tantalized scientists for decades, because if some way could be found to tap into ocean currents, a clean, inexhaustible source of energy could power our cities without adding to atmospheric gases that are changing the planet's climate in potentially catastrophic ways.

Florida officials are on record saying that the Gulf Stream could supply all the electricity the state needs, while helping to reduce those greenhouse gases. It's kind of a personal issue for Florida. Some experts believe Miami, which is just a few miles from the heart of the Gulf Stream, could be underwater by the end of this century because of rising seas due to global warming.

At this point, only one major problem looms on the horizon. Nobody is sure it will work.

"It's pretty much an untapped resource, and that includes knowledge," said Skemp, a past president of the American Society of Mechanical Engineers. "Some work on ocean currents has been done by a number of agencies and universities, but it's old information. So, when you are looking at tapping the ocean current today, there's a lot of long-term implications."

Within about a month, the researchers expect to begin placing a series of temporary sensors off the coast of south Florida, where the Gulf Stream passes through the Florida Straits between the coastline and the Bahamas. That's a basic science effort to understand the ecology and environment, as well as the potential resource.

That could be followed, possibly as early as next year, with a pilot program consisting of a three-bladed turbine, about 10 feet in diameter. That would still be a temporary research facility, but if it works without "unacceptable" losses of wildlife, it could be followed by turbines that would generate electricity that could be piped ashore.

That may sound basic, considering the growing number of similar turbines in wind farms across the country, but it's new territory in the ocean.

"No turbine has been deployed offshore in the Gulf Stream for more than a few hours and thus, little, if any, knowledge exists about in-situ performance of the technology," according to a description of the project on the center's Web page.

Skemp emphasizes that the project will move forward cautiously, because "we have to understand the migratory direction of fish and mammals and sea turtles. We're looking for the big picture. We have to understand the environment to make informed decisions."

Land-based turbines have proved to be deadly for migratory birds, a fact that few scientists anticipated, so will the same thing happen in the oceans? Skemp said the only evidence they have at this point comes from sea captains in the area who claim that "fish aren't stupid" and will swim around a turbine instead of trying to swim through it.

But nobody knows yet if they are right.

The Florida consortium, which includes the University of Florida, Florida State University, University of Central Florida, and the University of South Florida, is actually part of a larger international group that includes researchers and institutions in the United Kingdom. Skemp said England is ahead of the U.S. in understanding tidal forces, and information-sharing agreements are in place between the two countries. And the United States is in a good position to exploit the Gulf Stream.

"We have about 20 percent of the total energy of the Gulf Stream," off the coast of Florida, she said. The stream is actually two rivers, one underwater consisting of cold water flowing south from the Arctic, and a surface "river" which is the warmer Gulf Stream flowing north.

A number of previous efforts to tap into various ocean currents failed partly because the currents are spread so widely that it would require a prohibitively huge system to collect enough energy to be useful. But the Gulf Stream is concentrated off Florida, and does not meander much, so it may be easier to harness. Off the coast of North Carolina, for example, the stream widens out, so, although there is more water flowing past the Carolinas, it is spread over a much wider area.

Since the flow is more concentrated off Florida, the water moves past more quickly, at speeds up to four knots, like a river passing through a narrow gorge. And there's one major advantage over land-based wind farms: The water flows at a fairly constant speed, day and night, rain or shine, windy or calm.

The energy is there 24 hours a day, seven days a week, 365 days a year, Skemp said.

If the first efforts succeed, there may be another resource waiting in the stream. Due to the cold currents from the north, and the warm currents from the south, there is a substantial temperature differential which may someday also be converted into electricity, although that technology is still a bit immature. But, at the least, it should be possible to tap into the cold water and pipe it ashore to cool Florida's buildings, further reducing the dependence on greenhouse gases.

However, Skemp warns that this is still an embryonic industry, and it simply may not work, but she's optimistic.

"It's very exciting," she said. And it's a homecoming for her. She was born just off of what is now the Boca Raton campus of Florida Atlantic University, where she earned her degree in mechanical engineering. She spent years in the aerospace industry before returning to Florida.

"Once you get some sand in your shoes, it's hard to leave," she said. But she would probably love to flush that sand out with the warm waters of the Gulf Stream, harnessed at last.

Lee Dye is a former science writer for the Los Angeles Times. He now lives in Juneau, Alaska.