Fuel Frenzy

After you build the facilities it is free and works well as long as the water supply stays constant.

Hydro Power does account for about 20% of the electric power produced annually in the United States.

Most people think of Niagara Falls and Hoover Dam as very large power generators. Many will say Hoover dam can power all of California and Arizona. Sounds good but they would be wrong. Yes they are large generation facilities ( Hoover about 2000 Megawatts - Niagara Falls about 2500 megawatts ) but believe it or not many two reactor Nuke Power Stations produce about the same amount and the three unit site in Arizona, Palo Verde Nuclear Power Station produces more power (3000 + Megawatts)

Hoover Dam uses 100% of the flow of the Colorado River using Lake Mead as its reservoir. There is the problem. Lake Mead is being drained. Note the declining water levels in the graphic.

Is this decline from overuse, poor water management, long term weather changes or global warming? I do not know. The truth is that the West is in for a large disappointment in the next few years in both the water and electrical power areas without some major changes in Mother Natures Water Supply to the area.

In a 2008 report on the status of Lake Mead, scientists at the Scripps Institution of Oceanography predict there is a 50% probability that Lake Mead will be completely dry by 2021, because of climate change and unsustainable overuse of Colorado River water. The report concluded "Today, we are at or beyond the sustainable limit of the Colorado system. The alternative to reasoned solutions to this coming water crisis is a major societal and economic disruption in the desert southwest; something that will affect each of us living in the region".

The power of raised water:

Water stored at a level above your working level does store some potential energy.

Some utilities do this using the stored water somewhat in the same manner as a large battery. Charging it (pumping the water up to a higher level ) when electrical demand is low and discharging ( letting the raised water drop thru turbine generators ) it when peak demands are high. This works but is very inefficient, but if you have lotza cheap electricity at low demand times it is a way to level out your power generation demands.

How much power can be stored? As an example lets use a 1000 gallon storage tank raised 20 feet above your work area.

That is about 8000 pounds raised 20 feet or about 160,000 ft-lbs.
778 ft-lbs = 1 BTU so we have about 205 BTU
That is a long way from the 1,000,000 BTU used to heat your average home in a northern climate for one day.
Of course, as always, all the conversions and equipment used to change this raised water into electricity only reduce the power that is real world available from the raised water.

Niagara Falls is divided into the Horseshoe Falls and the American Falls . The Horseshoe Falls drop about 173 feet . The American Falls drop about 70 feet. The larger Horseshoe Falls are about 2,600 feet wide, while the American Falls are 1,060 feet wide. The volume of water approaching the falls during peak flow season is 202,000 cubic feet per second (5,720 m³/s). By comparison Africa's spectacular Victoria Falls has over 15 million cubic feet of water falling over its crest line each minute during the peak of the wet season (250,000 cu ft/7,079 m³ per second). Since the flow is a direct function of the Lake Erie water elevation, it typically peaks in late spring or early summer. During the summer months, 100,000 cubic feet per second of water actually traverses the Falls, some 90% of which goes over the Horseshoe Falls, while the balance is diverted to hydroelectric facilities. This is accomplished by employing a weir with movable gates upstream from the Horseshoe Falls. The Falls flow is further halved at night, and during the low tourist season in the winter, remains a flat 50,000 cubic feet per second . Water diversion is regulated by the 1950 Niagara Treaty and is administered by the International Niagara Board of Control

Here's how it works:

The Niagara project, located about 4 1/2 miles downstream from the Falls, consists of two main facilities: the Robert Moses Niagara Power Plant, with 13 turbines, and the Lewiston Pump-Generating Plant, with 12 pump-turbines. In between the two plants is a forebay capable of holding about 740 million gallons of water; behind the Lewiston plant, a 1,900-acre reservoir holds additional supplies of this liquid fuel.

Put very simply, we divert water from the Niagara River-up to 375,000 gallons a second-and convey it through conduits under the City of Niagara Falls to Lewiston. From there, water flowing through the Robert Moses plant spins turbines that power generators, converting this mechanical energy into electrical energy.
At night, when electricity demand is low, the Lewiston units operate as pumps, transporting water from the forebay up to the plant's reservoir.
During the daytime, when electricity use peaks, the Lewiston pumps are reversed and become generators, similar to those at the Moses plant. In this way, the water can be used to produce electricity twice, increasing production and efficiency.

To balance the need for power with a desire to preserve the beauty of Niagara Falls, the United States and Canada signed a treaty in 1950 that regulates the amount of water diverted for hydroelectricity production. On average, more than 200,000 cubic feet per second (cfs), or 1.5 million gallons of water a second, flow from Lake Erie into the Niagara River. The 1950 pact requires that at least 100,000 cfs of water spill over the Falls during the daylight hours in the tourist season, April through October. This flow may be cut in half at night during this period and at all times the rest of the year.