Hydroelectric power is a technology which produces electricity via hydropower, or the energy released by moving water, such as for instance water moving through the course of a river or falling downhill. In the United States today, most hydroelectric power is generated by water flowing downhill, and most of this downhill flow is achieved via the construction of artificial dams. The dams are constructed so as to engender sufficient water outflow volume by way of creating a significant “head” or, that is, the difference in height between the water’s source (or crest) and the water’s outflow.

A significant enough “head” is necessary to produce a sufficiently useful flow of energy from the hydroelectric power source. This is why dams constructed for the purpose of creating hydroelectric power are built as high as is feasible. Within these dams there are turbines which receive the force of the water’s flow, and the turning of the blades of the turbines generates the electrical current which is transferred to long-distance power lines and transformed into electricity for use in homes and offices.

In addition to the dams there are some tidal harnesses which have been constructed. These draw electrical power from the flow of the tide along a coastal area. In the United States, there is a heightened interest in creating many more small, unobtrusive tidal flow hydroelectric power generators in rivers and large streams which would be used just for generating local electricity. In Canada, there is so much electricity generated by hydroelectric facilities that they simply say “hydro” to refer to any public electricity utility, even nuclear power. Norway and Iceland also generate nearly all of their citizens’ needed electricity by way of hydroelectric power.

North America has the greatest hydroelectric power capacity. Canada is the world’s leading nation in that regard, and the United States is the world’s second leading nation.

Except in nations that have a proportionate abundance of the right natural resources (i.e. a lot of water), hydroelectric power is used to handle the supplying of electricity during high peak loads. Today’s greatest single interest in harnessing more hydroelectric power resides in the fact that it is a renewable source, or “alternative source”, of electricity, since obviously the planet will never run out of water and it doesn’t matter if the water utilized is potable or not.

The big concern about using more hydroelectric power is that it may disrupt ecosystems too much if more facilities (especially dams) are installed. A secondary concern is that water demand for hydroelectric facilities sometimes conflicts with irrigation demands.

The Greeks were using hydroelectric power to turn water-wheels for the grinding of grain over 2,000 years ago. Hydroelectric power was “rediscovered” in the 18th century in the U.S. and western Europe.

The first modern hydroelectric dam was completed in 1882 on the Fox River in Appleton, Wisconsin in the United States and could generate 12.5 kW of electrical power. It was based upon the ideas of American inventor Lester Allan Pelton, who invented a jet-free water turbine in 1880.

video in which Kathleen Packard, their Healthcare Market Development Manager, discusses how some innovations in lighting can positively affect the healing process (and save energy and money). Packard describes hospitals as being historically “institutional and very uncomfortable,” and her mission is to educate the public on the “importance of design” to patient health.

intrinsically photosensitive retinal ganglion cell in the human eye, which senses light and regulates the body’s systems, including melatonin levels, which are directly related to sleep. Visa’s Amber Night Light, she says, creates ambient light that won’t disturb the intrinsically photosensitive retinal ganglion cell. This allows nurses to check on patients without disturbing their sleep.

Of course, all this valuable information leads us to the problems solved by Visa Lighting’s healthcare light fixtures. Packard calls special attention to the benefits of using LED fixtures. She reminds us that LEDs are indeed a great option for hospitals because they are energy efficient and therefore save money, reducing the cost of healthcare; they render color well, which is necessary, so that doctors and nurses can accurately assess skin pallor; and, unlike fluorescent lamps, LEDs contain no mercury.