Hydropower: Offshore and Tidal
With the earth’s precious natural resources being used up and the pollution from our great use of fossil fuels, many nations and communities have turned to the use of alternative energy sources. Among those alternative energy sources is the use of tidal waves and currents to generate electricity. This source is known as offshore hydropower. The use of waves as an energy source is surprisingly an old method. Many farmers and settlers in the 1700s would create water wheels to generate electricity in their homes and boats. The first actual hydropower plant was built in 1880 in Grand Rapids, Michigan. At this plant, the electricity produced provided enough power to support a factory. In the 1930s and 40s, hydropower had a second revolution thanks to President Franklin D. Roosevelt’s New Deal Plan. This plan allowed for large scale construction of power plants which included hydro-plants. Generating electricity from the oceans has been discussed for the past forty years. Attempts have been made to harness both wave and tidal power, usually with little success. However, with advances in engineering and technology over the past few years, oceans and other large bodies of water have become an economically feasible source of energy. In the late 1990s, it had become clear that technology had advanced to the point that reliable and cheap energy could come from the ocean was a real possibility. The true definition of hydropower is the generation of electricity by the movement of waves and currents. Tidal power is a form of hydropower that converts the energy of tides into electricity or other useful forms of energy. The tides that generate the power for this energy source is created by the relative motion of the Earth, moon, and sun and the gravitational interactions between them. Every coastal region in the world has two high and two low tides every twenty-four hour period. This set schedule of the movement of the tides creates a big advantage for tidal energy because it gives it predictability. Offshore wave energy is a clean source of energy that can neither pollute or be consumed during its operation. This source of energy eliminates the cost of fuel to produce it which in turn makes it immune from the increasing price of fossil fuels. As long as there is a water source it is deemed renewable. There are four different ways to harvest offshore hydropower energy. Among those four ways are the terminator device, point absorber, attenuators, and overtopping devices. A terminator device extends in the direction of the wave and captures the energy of the wave. This type of device is typically used on or near the shoreline; however, new technology allows for the creation of floating versions that have been designed for offshore usage. Point absorbers are a floating device usually known to mankind as a buoy. Inside the buoy is a fixed cylinder that bobs to and fro. This motion is used to drive hydraulic energy converters to generate electricity. The electricity runs through a cord like chain that transports the energy into a generator onshore. On the other hand, attenuators are long, floating construction pieces that run parallel to the water and the direction of the waves. The differing sizes of the waves along the length of the attenuator causes contracting where the segments connect and this contracting is connected to other converters which in turn generate the energy. Lastly, overtopping devices have reservoirs like onshore hydropower dams. These reservoirs are filled by incoming waves that are higher than the surrounding ocean. Water is then released with the help of gravity causing it to fall back towards the ocean’s surface and into the turbines creating an electric current.
Offshore resources have better and stronger power than on the shoreline, but the problem with offshore resources is that it is harder to reach it if there are maintenance problems. There are many different types of