The era of large, new hydropower projects is over, at least in the United States.
But electricity generated from traditional hydropower — those big dams that aren’t going away any time soon — as well as from new hydrokinetic technologies such as tidal and oceanic power offers both many benefits and the possibility of incremental improvement.
Plus, water-powered electricity plants are extremely cost-effective. The main cost of most water-powered facilities is their initial construction and installation — there are no perpetually incurred fuel costs — and once a dam or a turbine exists, its maintenance and operation costs are minimal.
Experts have suggested that if current stocks of traditional hydroelectric power were reduced in certain regions of the country, no other source of generation could immediately replace that output — possibly leading to substantial spikes in wholesale electricity prices during peak demand periods.
Traditional hydropower is also the only currently viable way to “store” significant amounts of electricity. Technically, electric energy must be consumed as it is generated, but water stored behind a dam gets around this constraint by storing kinetic energy embodied in the pent-up water, which at the flip of a switch can be turned into electrical energy as the water falls through mechanical turbines.
This has important implications for “moving” energy between time periods, smoothing overall electricity supply and keeping prices from spiking to meet demand. This “shifting” characteristic of traditional hydropower alone has led many to conclude that one of the most important factors in determining the potential for market power in deregulated electricity supply systems is the level of available hydroelectric capacity.
Slideshow: Notable dams in the United States
Water power, therefore, proves fundamentally important to the overall U.S. electricity industry. Unfortunately, supplies of traditional hydropower in the U.S. have been decreasing steadily for more than a decade, and new hydrokinetic technologies are still in their infancy. Can we do anything to maintain, or even improve upon, current stocks of water-powered electric capacity?
We cannot build new, large hydroelectric dams; they have significant negative effects on migrating fish and local riverbeds. While the benefits of traditional large hydro development are questionable, however, efficiency improvements at existing dams, called “uprating,” have the potential to increase hydropower production from as little as 8 percent to as much as 50 percent.
This comes without any increases in reservoir size or dam size and with, through improved turbine technology, diminishing fish mortality levels. The increasing cost of energy and the need to find fossil fuel alternatives, combined with the concern over fishery impacts of large dams, has led to a considerable acceleration of research over the last decade into technological improvements for fish passage and protection.
At Wanapum Dam in Washington state, for example, a new, advanced-design turbine is providing increases in power output of 14 percent, a water-use efficiency gain of 3 percent, and fish passage survival of 97.82 percent — a record.
These new turbines are expensive, but as the cost of energy increases, such options become more cost-effective. The Low Impact Hydropower Institute, a nonprofit organization “dedicated to reducing the impacts of hydropower generation,” has developed a program that provides certification for environmentally acceptable development of hydropower at existing dams. As of 2007, LIHI has certified 28 facilities, in 19 states, producing nearly 2,000 megawatts of power.
It is also possible to develop new hydropower facilities at existing dams. The National Inventory of Dams documents more than 79,000 dams in the United States. Less than 3 percent of these currently feature developed hydropower capacity; most were built for such purposes as irrigation, navigation or flood control. Adding hydropower facilities to these dams would bring relatively little in additional negative riverine effects but could generate substantial amounts of renewable energy.
Not all facilities could be developed profitably, of course, and studies would need to be conducted at the individual site level to determine capacities and realized environmental effects, but even a slight increase in development of existing dams for hydroelectric power production could lead to large increases in energy production. In 1998, the Department of Energy made a very conservative estimate of “environmentally friendly” capacity additions to existing large dams and came up with 17,000 megawatts of potential, distributed across the United States.
Plus, there is a history of cost-effective private development of new hydropower facilities at existing dams.
Finally, the future holds promise with a number of emerging technologies that utilize river and ocean water to develop emissions-free, environmentally benign electric power. Hydrokinetics, the study of fluid in motion, is being developed to access the energy in river, tidal and ocean currents to generate electric power. Early estimates point to these sources as providing, at a minimum, an additional 23,000 megawatts of power in the United States.
Hydrokinetic and wave energy technologies require no impoundments, rendering irrelevant the negative environmental effects associated with dam construction and reservoir creation.
While these technologies are still very new, prototypes continue to pop up with increasing frequency in New York, Washington, Oregon, California and Florida. In 2006 the Federal Energy Regulatory Commission received more than 40 applications for preliminary permits for potential hydrokinetic projects, and in 2007 FERC issued a notice seeking public comment on how to streamline permitting and licensing of these facilities.
The data on hydrokinetic potential nationwide are still very preliminary, and any potential power will be located primarily along the coasts, where current wave and tidal prototypes are employed. Future hydrokinetic technologies, however, will also take advantage of the wave power in streams and rivers, and this will benefit many of the inland states.
Water power is important to our nation’s overall electricity security. These avenues for maintaining current water power capacity, while not simultaneously adding significantly to negative riverine effects, deserve our attention.
