The Essential Engineer by Henry Petroski

Author:Henry Petroski [Petroski, Henry]
Language: eng
Format: epub
ISBN: 978-0-307-59320-7
Publisher: Knopf Doubleday Publishing Group
Published: 2010-04-14T16:00:00+00:00

Other renewable energy sources include the ocean’s waves and tides, which some scientists believe to be vast unexploited resources. According to one estimate, harnessing just 0.1 percent of the ocean’s energy could supply the electricity needs of fifteen billion people. Although the wind does not always blow or the sun always shine, the twice-daily tides represent a totally reliable source of power. Pas-samaquoddy Bay, at the mouth of the St. Croix River, which runs along the border between New Brunswick, Canada, and Maine, has the greatest tidal change in water level (about twenty feet) of any location in the continental United States. President Franklin Roosevelt, whose summer retreat on Campobello Island was not far from the largest whirlpool in the Western Hemisphere, promoted the Passamaquoddy Bay tidal power project. Like the tide mills that once drove industries throughout coastal Maine, the Roosevelt project relied on dams and impoundments that trapped water at high tide and released it at low tide to produce power. The new approach employs tidal stream turbines that, because the density of water is so much greater than that of air, can be many fewer in number than wind turbines to produce the same amount of power. And, because the stream turbines are underwater, their installation draws much less opposition attributable to ruined views or disturbed tranquillity than do massive wind turbines that tower and hum over the water. Although by some estimates deriving power from the tides is more than a decade behind extracting it from the wind, the technology is believed to be in place: “It’s just a matter of engineering it for the lowest cost, the highest reliability and the longest survivability in a hostile and corrosive environment.” Still, that kind of engineering does take time. Meanwhile, tidal power is definitely emerging, albeit slowly, as a technology to watch.24

Another reliable source of water power is the Gulf Stream, which provides a constant flow of more than eight billion gallons per second. If turbines are placed in the stream at a depth of thirty to forty feet below the surface of the water, they will be out of reach of shipping, and the power they generate can be transmitted through undersea cables. Such a scheme, employing thousands of turbines, might produce as much power as ten nuclear plants and supply one-third of the electricity needs of Florida. All such projects tend to think big but necessarily start small: exploiting the Gulf Stream began with a $5 million grant from the state of Florida, which would enable further study, including the installation of a small test turbine. Even should such a project recover from anticipated early setbacks, it will have to contend with opponents who worry about the “Cuisinart effect,” in which the spinning blades might be capable of chopping up sea creatures, including fish. The wind turbine industry had to deal with the idea that it would do the same to birds.25

Some projects to harness the energy in the sea have had bad luck with

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