History of Tidal Power
Believe it or not, tidal power is nothing new. In fact, most of what we use today to generate electricity, be it coal, solar, wind, or tide, was conceived of in the later part of the nineteenth century. In Europe, 'tide mills' that date back to the Middle Ages can still be found, indicating that this is a very old technology indeed. In Suffolk, England, there is a tide mill that dates back to 1170. The oldest known reference to a tide mill dates back to 787.
These original tide mills work much like the concepts of today with the only difference being that they did not generate electricity in 1170. The mill at Suffolk is a good example of how the concept worked. Basically, a dam was built to contain the tide when it was high. Once the tide fell, the contained water was directed into a sluice where it pushed a wood water wheel that was then used to turn machinery of varying sorts (mostly stones for grinding grain). The concept today is basically the same except that the water wheel is replaced with a steel turbine (similar enough to a water wheel) and rather than turn stones to grind grain, the turbine spins a generator to produce electricity.
The concept of the tide mill was brought to North America with the settlers. Maine, in particular, has witnessed almost continual use of tide mills since the eighteenth century. In the latter part of the nineteenth century, the concept of tidal power was turned to the generation of electricity. In 1921, a book was published in London entitled Tidal Power by A. M. A. Struben. The book outlined several methods for capturing energy from the tides.
In 1920, an engineer by the name of Dexter Cooper came up with the idea of creating power from tides, a plan that he intended to implement in Cobscook and Passamaquoddy bays. Early funding was robust, the stock market crash of 1929 quickly put an end to work.
A few years later, Franklin D. Roosevelt, an early supporter of Cooper, became President of the United States and the federal government undertook a study of the tidal power plant proposed by Cooper. Unfortunately, they decide that the project would be too expensive and handed over authority to a committee in the state of Maine. The committee decided the project could only proceed if federal funds were allocated and Roosevelt himself commissioned seven million dollars (the maximum possible without congressional approval) for the project through the Public Works Administration.
Eventually the project was stopped when Congress refused further funding, but the idea has remained in the minds of the people of Maine ever since. In 1961, the project was again considered by an international cooperative between the United States and Canada. The cost analysis showed that the project would only benefit the United States and so the project was again sidelined. In 1977, Canada undertook yet another study of the bay, but again decided that the project was not beneficial, though it was deemed cost effective. Today, progress is halted mainly by the large impact such a project will have on the ecology of the bay. It is not clear how extensive the impact will be, but it is likely to be substantial enough to affect the lucrative fishing industry that thrives in that region.
France has been the leader in the implementation of tidal power in the modern era. Their first tidal mill was built in Brittany in the 12th century and was followed seven hundred years later by a tidal power plant in the same location. The plant represents the first commercial-scale tidal power plant and has been in continuous operation for nearly forty years. The location of the plant is ideal because the tide in that area reaches heights of over forty-four feet. It currently produces 240 megawatts, which is roughly a third of the output of the average coal-fired plant. To generate this electricity, the plant uses the tidal barrage method and relies on a dam that holds back roughly 6.5 billion cubic feet of ocean water.