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Hydro Energy
Definition:
Using water to power machinery or make electricity. The water used in the process is not reduced or used, as are fossil fuels. Because the water cycle is an endless, constantly recharging system, hydropower is considered a renewable energy.
Types:
There are several types of hydroelectric facilities; they are all powered by the kinetic energy of flowing water as it moves downstream. Turbines and generators convert the energy into electricity, which is then fed into the electrical grid to be used in homes, businesses, and by industry. (additional descriptions and images of hydropower plants can be found here)
Hydropower plants:
Impoundment - The most common type of hydroelectric power plant is an impoundment facility, typically a large hydropower system that uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level.
Diversion - A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock. A diversion can utilize the flow of water within the natural range of the river, requiring little or no impoundment.
Pumped Storage - When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity.
Microhydropower Projects - Microhydropower produces 100 kilowatts (kW) or less. Microhydro plants can utilize low heads or high heads. Micro hydro systems can also complement photovoltaic solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.
Hydropower Turbines:There are two main types of hydro turbines: impulse and reaction. The type of hydropower turbine selected for a project is based on the height of standing water—referred to as "head"—and the flow, or volume of water, at the site. Other deciding factors include how deep the turbine must be set, efficiency, and cost.
Impulse Turbine - The impulse turbine generally uses the velocity of the water to move the runner and discharges to atmospheric pressure. The water stream hits each bucket on the runner. There is no suction on the down side of the turbine, and the water flows out the bottom of the turbine housing after hitting the runner. An impulse turbine is generally suitable for high head, low flow applications.
Reaction Turbine - A reaction turbine develops power from the combined action of pressure and moving water. The runner is placed directly in the water stream flowing over the blades rather than striking each individually. Reaction turbines are generally used for sites with lower head and higher flows than compared with the impulse turbines.
Benefits:
- Hydropower is fueled by water, so it's a clean fuel source. Hydropower doesn't pollute the air like power plants that burn fossil fuels, such as coal or natural gas.
- It is a domestic source of energy, produced in the United States.
- Hydropower relies on the water cycle, which is driven by the sun, thus it's a renewable power source.
- It is generally available as needed; engineers can control the flow of water through the turbines to produce electricity on demand.
- Hydropower plants provide benefits in addition to clean electricity. Impoundment hydropower creates reservoirs that offer a variety of recreational opportunities, notably fishing, swimming, and boating. Most hydropower installations are required to provide some public access to the reservoir to allow the public to take advantage of these opportunities. Other benefits may include water supply and flood control.
- Cost - For many applications, the advantages of PV systems offset their relatively high initial cost.
Potential Benefits:
- Nearly 40% undeveloped capacity in the U.S., according to US Department of Energy.
- US Department of Energy has identified 5,677 sites in the United States with undeveloped capacity of about 30,000 MW. By comparison, today there are about 80,000 MW of hydroelectric generating plants in the United States.
- Average per KWH Power Production Expenses from 1990 - 1994: approximately 0.065 for hydropower compared with $0.24 for fossil-fueled steam and nuclear steam or $0.46 for gas turbine/small-scale.
Challenges:
- Fish populations can be impacted if migration routes are blocked by impoundment dams. Upstream fish passage can be aided using fish ladders or elevators, or by trapping and hauling the fish upstream by truck. Downstream fish passage is aided by diverting fish from turbine intakes using screens or racks or even underwater lights and sounds, and by maintaining a minimum spill flow past the turbine.
- Although there are substantial undeveloped resources in the United States, hydropower's share of the nation's generation is predicted to decline through 2020 to about 6% from about 10% today. The decline is due to environmental issues, regulatory complexity, and energy economics. Energy analysts expect almost no new hydropower capacity to be added through 2020.
- Hydropower can impact water quality and flow. Hydropower plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydropower installation is also critical for the survival of riparian habitats.
- Hydropower plants can be impacted by drought. When water is not available, the hydropower plants can't produce electricity.
- New hydropower facilities impact the local environment and may compete with other uses for the land. Those alternative uses may be more highly valued than electricity generation. Humans, flora, and fauna may lose their natural habitat. Local cultures and historical sites may be impinged upon. Some older hydropower facilities may have historic value, so renovations of these facilities must also be sensitive to such preservation concerns and to impacts on plant and animal life.
Tools / Incentives:
- Federal Energy Regulatory Commission: http://www.ferc.gov/industries/hydropower.asp
The Commission's responsibilities include: Issuance of licenses for the construction of a new project; Issuance of licenses for the continuance of an existing project (relicensing); and Oversight of all ongoing project operations, including dam safety inspections and environmental monitoring.
- Idaho National Laboratory - DOE National Laboratory for hydropower engineering and program management support: http://hydropower.inel.gov/
The mission of the U.S. Department of Energy's (DOE's) Hydropower Program is to conduct research and development (R&D) that will improve the technical, societal, and environmental benefits of hydropower and provide cost-competitive technologies that enable the development of new and incremental hydropower capacity, adding diversity to the nation's energy supply. The lead laboratory for engineering and program management support is INL. View INL's New Hampshire Hydropower resource assessment.
- Hydro Research Foundation, Inc.: http://www.hydrofoundation.org/
The Hydro Research Foundation, Inc. [HRF] was established in 1994 and became an independent 501 (c) (3) non-profit corporation in 1996. The foundation has two principal objectives: to facilitate research and to promote educational opportunities that communicate the value of hydropower.
- National Hydropower Association: http://www.hydro.org/
The National Hydropower Association (NHA) is a nonprofit national association dedicated exclusively to advancing the interests of the hydropower industry. It seeks to secure hydropower's place as a climate-friendly, renewable and reliable energy source that serves national environmental and energy policy objectives.
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Design Standards /
Land Use Regulations
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Related Images
(click image to enlarge)
Impoundment hydropower plant, Ashland, NH
Diversion hydropower plant, Campton, NH
Hydropower turbine, Campton, NH
Idaho National Laboratory: Microhydropower facility
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