Technology – Water Power and Geothermal Energy
As fossil fuel resources are used up and concern about their environmental effects increases, alternative forms of energy are gaining prominence: water and geothermal energy are two of the most important.
Energy in the natural world can take many forms-from heat deep within Earth to the kinetic energy of ocean waves, rivers, and wind. To convert this energy into us- able forms, various processes are used to produce electricity, heat, or fuel. Some processes have proven cost-effective and are already in use.
Others are still in the testing phase or exist only on paper. The search for renewable energy is driven by the need to reduce carbon dioxide emissions and to get independent of fossil fuels.
Water power
Most hydropower plants use generators to convert kinetic energy into electricity, such as low-pressure hydropower plants are installed in rivers. High-pressure power plants, located in dams, transform the potential energy of water in the reservoir into kinetic energy. Innovative new tidal power stations use the movement of seawater to produce an air current, which drives a propeller to produce electricity.
Experimental osmotic devices create pressure using various combinations of freshwater and saltwater, and wave generators use the motion of waves to produce electricity by induction.
Geothermal energy
Geothermal technology makes use of the high temperatures found deep in the Earth. Hot water is brought up from a drilled bore- hole and then utilized directly for heating, or transferred to a heat pump to produce electricity.
Through a second borehole, an equal amount of cold water is returned to the ground. A variation is the “hot dry rock” method, used in places with high temperatures and without natural water supplies.
Water is first pumped into the ground to be heated before being returned to the surface. Geothermal power is considered to be one of the best potential renewable energy sources. At this stage, however, the technology is still in its early phases.
SEAFLOW TURBINES
A pilot program of seaflow turbines has been in operation off the British coast since 2002. Ocean currents from the tides cause huge rotor blades to turn, and this energy is then transferred to a generator. A current of some eight feet (2.5 m) per second is enough to produce 350 kilowatts of relatively constant electrical power—to- tally independent of the weather.
The company responsible for the project envisions installations with a capacity of one megawatt each, consisting of twin-rotor towers. These facilities would be capable of supplying 40 percent of Great Britain’s electricity need