Tidal power has been in use for over 1000 years, with some of the earliest records being dated back to 900 A.D., through the
use of tidal mills. One well known project was the Passamaquoddy Tidal Power Development Project of the 1930's. This project came about during the Great Depression and was led by Dexter Cooper. Cooper had ideas of trapping water into gates and dams, and then releasing it through turbines. Cooper’s project would have worked if it weren’t so expensive: during the fall of 1935, the
federal funding was cut half.
It was not until the 1960’s that the first commercial-scale modern-era tidal power plant was built, near St.
Malo, France. Across Europe, in France and in England, small tidal mills were
built to grind grain that had been harvested, which were usually grinded into flour. Power was usually available for about
two to three hours, twice a day. In Hayle, England, tidal power was used to “dredge”
a shipping channel by flushing it regularly with a pulse of stored tidally-impounded water.
These tidal mills were situated in estuaries which, when the tide came in, filled with seawater, after which a sluice
dropped down, preventing the water from flowing out when the tide receded. Once the tide was low enough, the water was funneled
out through one or more water wheels, and powered the mill as it receded. The mills were used for many more years, but using
the tides to directly generate power was not accomplished until 1967.
In 1967, the first electricity-generating
tidal plant was built at the intersection of the Rance River and the English Channel, in France. Plans to build the facility
stretched as far back as 1943, when the Society for the Utilization of The Tides commissioned a study to examine the Rance
for potential for a tidal plant, but construction did not actually begin until 1961. The La Rance facility produces around
600 million MW of power a year, about .012% of France’s total electrical use. The turbines used at the La Rance facility
were and still are 10 megawatt low-head bulb turbines.
The second commercial-scale tidal
electricity plant was built at Annapolis Royale in Nova Scotia, Canada. It was built in 1982, and uses the STRAFLO turbine
design. The STRAFLO design is a modification of the Kaplan Turbine design, where the turbine is mounted vertically and actually
retains the water temporarily before releasing it to the other end of the turbine and into the tidal basin.
The first major use of tidal
turbines has been commissioned by Verdant Power on the East River of New York City. Verdant Power put 2 turbines in initially
as a test in 2002, marking a milestone for tidal power. The turbines performed properly, until both turbines lost blades to
the surprising force of the tide. Shortly afterwards, Verdant replaced the 2 turbines with turbines built with cast-aluminum
blades, to strengthen the blades, and installed 4 more turbines using the same design. These 6 new turbines lasted longer,
but eventually succumbed to the tide as well. 5 of the turbines running together produced nearly 1000 kilowatt hours per day.
Verdant's initial plan called for up to 300 turbines in the water area, which could produce enough energy per day to power
800 houses and compete with current energy vendors. Verdant has no plans to forgo the project, and is currently researching
to put more turbines back in soon.
