Tidal Power As A Source Of Electricity
Tidal energy has been used by humans for hundreds of years. In the modern era, the power is utilized for the production of electricity. The technologies involved are both proven and effective. However, with the exception of a tidal power plant at La Rance, France, the energy resource remains largely undeveloped. This may be in part because of the relatively high cost of the electricity produced. Only in appropriate circumstances will tidal power ever utilize its potential as both a dependable and enduring power source.
Tidal surges are caused by complex interactions between the gravitational fields of the sun and the moon. These phenomena occur in cycles of varying length. For the most part, the earth's oceans bulge along an axis which is approximately in line with the moon. As the earth rotates, its surface moves with respect to this bulge (Sanders, 1991, p. 273). The result is a half-day tidal cycle of 12 hours and 25 minutes between successive high waters. However, other cycles exist as well. One of these is caused by interaction between the gravitational fields of the sun and the moon. It occurs over a 14 day period and results in tidal maximums and minimums known as the spring and the neap tides, respectively (Twidell & Weir, 1986, p. 344). Spring tide ranges tend to be about twice those of neap tide. All tides, however, may be affected by local influences. Such factors as tunnelling, reflection, and resonance can dramatically alter tidal range at any given point along a coastline (Cavanagh et al., 1993, p. 515).
Along the shores of Europe, records indicate that tide mills have been in operation since before AD 1100. The earliest mills were extremely simple. During a flood tide, water would enter a storage pond through a sluice. Then, at low tide, this water would be used to turn a water wheel (Cavanagh et al., 1993, p. 518).
More recently, the technologies req...