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By Robert Rapier on Nov 16, 2007 with no responses

Harnessing the Tides

Tags: tidal energy

I saw an interesting story from the Miami Herald a few days ago:

Keys man’s dream: Harnessing the tides

KEY WEST — Douglas Bedgood recently stood on a defunct Henry Flagler railroad bridge, watching as the tide forcefully moved water from the Gulf of Mexico through a channel to the Atlantic Ocean.

What he saw was untapped energy. Enough tidal power, he believes, to light and cool every residence and business in the Lower Keys.

To capture that power and convert it to electricity, Bedgood founded Florida Keys Hydro Power Research Corp. in July. The nonprofit is working to put underwater tidal turbine farms in the Keys’ channels.

“People have been talking about this for a long time: Why not use the tides?” said Bedgood, 65. “But everybody was waiting for government or somebody else to do it. So it never got done.”

I have wondered about this for a long time as well. It seems to make perfect sense, and I didn’t understand why we aren’t exploiting this to the fullest extent. Then, I recently went to a presentation on the status of tidal energy, and found that those tides and the salt water play havoc with the equipment. The generators have to be built to withstand the most powerful tide they will ever encounter, and that drives up the cost. And on top of that, the tides still tear them up.

No offense, but I did find a bit of humor in this paragraph:

Bedgood, a massage therapist who has developed aquatic therapy devices and tried to build a wind farm in California in the 1970s, said his motive is green — but not for the color of money: “I want to do my part to save the planet.”

Finally, a few of the details:

The goal: To clump enough turbines — at least 300 — to create 160 megawatts of electricity while doing virtually no damage to the channel site or its marine life, part of Florida Keys National Marine Sanctuary.

At peak usage, the Lower Keys use 140 megawatts.

The first major step is getting the test turbine, dubbed “the football” because of its shape, into Bahia Honda Channel near mile marker 36. The turbine has four 4 ½-foot long paddles on each end to capture the tides going in and out. It will be anchored on hard sea bottom where there’s scattered small corals and no sea grass, and where the water is as much as 30 feet deep so it would not interrupt navigation, Bedgood says.

“We know it will work to get power,” said project manager Steve French of Stuart-based Applied Concepts Unleashed. “The question is how much can we get and how efficiently can we get it?”

Finally, a word about costs:

While the tides are free, producing energy from them is not.

Each turbine is expected to cost about $100,000. Bedgood said it will cost millions for the cable system and substation. To date, he has provided all the financing for his end of the project, which he expects will cost about $15 million to get the first 10 turbines up and running. He’s searching for private charitable contributors.

I hope they are successful. Tidal always seemed like a great idea to me. The devil, though, usually is buried in the details.