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ADVANTAGES OF HYDROELECTRIC POWER PLANTS

• Hydroelectric power plants generate no CO2, CO, NOx, SOx, particulates, ground contamination, or waste products. Some heat is imparted to the stream or river water as a result of friction with the turbine components, but this is not always significant.

• Water is a renewable source of energy, as long as the stream or river does not dry up. The hydrologic cycle replenishes the source of potential energy in the form of rainfall, snowfall, and runoff.

• Hydroelectric power plant output can be controlled at will by changing the volume of water fl ow per unit time.

• The reservoirs created by an impoundment or pumped-storage power plant can be used for recreational purposes, and may also provide dramatic scenery.

• The reservoirs created by impoundment are generally clean, because impurities precipitate to the bottom. They can often be used as sources of water for drinking, bathing, washing, or irrigation.

LIMITATIONS OF HYDROELECTRIC POWER PLANTS

• Large reservoirs flood land that could be used for something else. Whole towns have been sacrificed to reservoirs, causing displacement, resentment, and economic hardship.

• If a dam fails in a large impoundment facility, a catastrophic flood is almost certain to occur downstream.

• Hydroelectric power plants are not practical in regions where the terrain is flat.

• A prolonged drought can adversely impact, or even cut off, the energy production capacity of a hydroelectric power plant.

• In impoundment and pumped-storage power plants, the water level in the reservoir(s) varies considerably. One cannot expect to build a “beach house” directly on a reservoir!

• A dam can cause low dissolved-oxygen levels in the reservoir, because it brings the normal river flow to a nearly complete halt. This can kill fish and affect the nature of plant life in and around the reservoir.

• Dams can interfere with fish spawning. This problem can be mitigated by the use of fish ladders, fish elevators, or trapping and hauling the fish. However, such measures add to the cost of system construction or operation.

Circulating at a faster rate, unglazed collectors can provide acceptable efficiency.

But that’s not all!

In some hot climates, pools can have a tendency to overheat. Solar collectors can save the day here!

By pumping water through the collectors at night it is possible to dump excess heat. This technology isn’t just applicable to small pools at home, large municipal pools are also heated by solar technology in a number of cases. Take for instance the International Swim Center at Santa Clara, California, 13,000 square meters of solar collector heat a total of 1.2 million gallons of water a day!

Do we need to use solar thermal power directly?

If we consider power generation on a large scale, all of our power stations whether they be nuclear, coal, oil, or gas fired, all produce heat primarily, and then use this heat to produce steam, which then, through using rotating turbines, produces electricity.

This means, that at present, we do not produce electricity directly from chemicals, like we do in a battery—we first produce heat as an intermediate process, which is in turn used to produce electricity.

Once we recognize this, we quickly realize that it could be possible to use solar thermal energy to raise steam to generate electricity. And this is exactly what they are doing in Kramer Junction, California.

Tip

Enerpool is a free program that can be used to simulate your swimming pool being heated with solar collectors. By inputting information such as your location, and how the pool is covered. The program can predict what temperature your pool will be at, at any given time!

www.powermat.com/enerpool.html