Can you answer these questions?
• What creates the energy in hydroelectric power?
• How is energy harnessed from inland water?
• What are the advantages and disadvantages of using hydroelectric energy?
Join us on the field trip to find out!
Think of the sound of a large waterfall, or the sound of ocean waves crashing against the shore. The sound is strong and powerful. Water has mass. Coupled with gravity, that moving mass has great kinetic energy. Water's kinetic energy can be harnessed and is called hydropower. Various sources of water energy, such as waves, tidal action, and flowing rivers and streams, can be used to create electricity. Our field trip today will focus on hydropower and in particular, hydroelectric dams.
Because water is the energy source and its flow is ensured by the hydrologic cycle and gravity, hydropower is considered a renewable energy. Using renewable energy is important in establishing global sustainable systems and reducing our country's dependency on non-renewable resources such as coal, oil, and natural gas.
As part of the ecological infrastructure, the hydrologic cycle constantly distributes water throughout the land, soil, rocks, oceans, and atmosphere. At the oceans' edges the energy in waves can be harnessed with devices such as oscillating water columns (OWC) and salter ducks. The pressure of waves hitting an OWC causes the air inside the column to compress and be forced through turbines. Salter ducks are chains of floats that bob up and down in the water. The up and down motion turns a pump that creates energy. Both these devices are mostly experimental but are being used in Japan and Norway to generate commercial power (Water Power Inc. 1996-2002). Canada, France, Russia, and China are also capturing tidal energy. When the tide comes in the water flows through a turbine to create electricity. Before the water recedes a barricade is set to hold water back as the tide goes out. Once the tide is out the barricade is removed, releasing the water through turbines (Water Power Inc. 1996-2002).
On land the hydrologic cycle maintains water in vast watersheds comprised of rivers, streams, lakes, and wetlands. Gravity causes the water in rivers and streams to flow. The kinetic energy in water is harnessed by damming the stream or river and then controlling the rate of water flow through pipes in the dam. As the water flows through the pipes in the dam it turns blades on turbines and the turbines generate electricity. Rivers that have steep slope and are in deep valleys are ideal locations for hydroelectric dams. Many countries such as Canada, China, South America, and the United States have great untapped hydroelectric potential. Care must be taken when considering a site's hydroelectric potential because many ideal sites for hydroelectric dams are located on pristine protected land or are far from the people that need the electricity.
Nevertheless, about one-fifth of the world's electrical needs are currently supplied by hydroelectric dams (Chiras 2001). If an ideal location is available there are small-scale units that do not impede waterways but yet generate enough electricity for a single home or business. In contrast, next to the pyramids in Egypt, hydroelectric dams are some of the largest human-made structures in the world. The largest dam in the world is the Itaipu, on the border of Brazil and Paraquay, generating 12,600 megawatts of electricity, which supplies 25% of Brazil's electricity and about 80% of Paraquay's. Surpassing these will be the Three Gorges Dam currently under construction on the Yangtze River in China. It will generate 18,000 megawatts of electricity.
The largest concrete structure in North America is the Grand Coulee dam in the state of Washington. It generates 6,500 megawatts of electricity. More familiar to you may be Niagra Falls located on the Niagra River in western New York and southeastern Ontario. Canada and the United States both have hydroelectric dams on the Niagra River. The Canadian hydroelectric station generates 1,815 megawatts and the American hydroelectric station generates 2,400 megawatts. Both stations are located about four miles down river from the falls and operate off of water that has been diverted from the river above the falls.
Our objectives for this field trip are to:
- learn how hydropower creates electricity
- learn the advantages and disadvantages of hydropower
The Kinzua Hydroelectric Dam in Warren county is about 45 minutes from Erie, Pennsylvania.
As we tour the facility be sure to make note of:
- the technology, how the electricity is generated and the megawatts of electricity produced, and
- the cost involved in the development and maintenance of the site and structures
Also note how the electricity is sent to the power grid and the overall impact, good and bad, on the environment and the community.
On this field trip you will learn the following specifics of electricity generation:
- water held back in reservoir
- controlled release through the penstock to the turbines in the power plant
- spinning turbines produce electricity (flow of electrons)
- some water is pumped uphill into a holding reservoir to be released to generate electricity when water from the reservoir is low
- megawatts of electricity produced
- water discharged into river
- water downstream from the dam is regularly monitored for acidity (pH), oil/grease content, and water flow rate
