Water Power

( Original Source : Wikipedia Encyclopedia, Photo : Google Images )

Energy in water (in the form of motive energy or temperature differences) can be harnessed and used. Since water is about a thousand times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.

The reservoir created for hydroelectric dams may initially produce significant amounts of carbon dioxide and methane from rotting vegetation. Once this vegetation is gone, no additional greenhouse gases are produced. In some cases they may produce more of these greenhouse gases than power plants running on fossil fuels. They also affect water quality, creating large amounts of stagnant water without oxygen in the reservoir, and excessive air bubbles in the water downstream from the dam, both of which impact aquatic life. Failures of large dams, while rare, are potentially. Though the dams can be built stronger, at greater cost, they are still prone to sabotage and terrorism. Smaller dams and micro hydro facilities are less vulnerable to these threats. Wave and tidal stream power demonstration projects exist, but large scale development requires additional capital.