Hydropower Fact Sheet PDF

Hydropower Hydropower at a Glance, 2017 What Is Hydropower? Classification:...

Hydropower Hydropower at a Glance, 2017 What Is Hydropower? Classification: — renewable Major Uses: — electricity Hydropower (from the Greek word hydor, meaning water) is energy that comes from the force of moving water. The fall and movement of water U.S. Energy Consumption: U.S. Energy Production: is part of a continuous natural cycle called the water cycle. — 2.767 Q — 2.767 Q — 2.83% — 3.14% Energy from the sun evaporates water in the Earth’s oceans and rivers and draws it upward as water vapor. When the water vapor reaches the Data: Energy Information Administration cooler air in the atmosphere, it condenses and forms clouds. The moisture eventually falls to the Earth as rain or snow, replenishing the water in the oceans and rivers. Gravity drives the moving water, transporting it from high ground to low ground. The force of moving water can be extremely The Water Cycle powerful. Hydropower is called a renewable energy source because the water on Earth is continuously replenished by precipitation. As long as the water SOLAR ENERGY cycle continues, we won’t run out of this energy source. History of Hydropower CONDENSATION Hydropower has been used for centuries. The Greeks used water wheels (Gas to Liquid) to grind wheat into flour more than 2,000 years ago. In the early 1800s, American and European factories used the water wheel to power machines. The water wheel is a simple machine. The water wheel is located below PRECIPITATION a source of flowing water. It captures the water in buckets attached to (Liquid or Solid) the wheel and the weight of the water causes the wheel to turn. Water EVAPORATION EVAPORATION (Liquid to Gas) (Liquid to Gas) wheels convert the potential energy (gravitational potential energy) of the water into motion. That energy can then be used to grind grain, drive sawmills, or pump water. In the late 19th century, the force of falling water was used to generate OCEANS, LAKES, RIVERS electricity. The first hydroelectric power plant was built on the Fox River in (Liquid) Appleton, WI in 1882. In the following decades, many more hydroelectric plants were built. At its height in the early 1940s, hydropower provided 33 percent of this country’s electricity. By the late 1940s, the best sites for big dams had been developed. Inexpensive fossil fuel plants also entered the picture. At that time, A dam serves two purposes at a hydropower plant. First, a dam increases plants burning coal or oil could make electricity more cheaply than the head, or height, of the water. Second, it controls the flow of water. hydro plants. Soon they began to underprice the smaller hydroelectric Dams release water when it is needed for electricity production. Special plants. It wasn’t until the oil shocks of the 1970s that people showed a gates called spillway gates release excess water from the reservoir renewed interest in hydropower. during heavy rainfalls. Hydro Dams Hydropower Plants It is easier to build a hydropower plant where there is a natural waterfall. As people discovered centuries ago, the flow of water represents a huge That’s why both the U.S. and Canada have hydropower plants at Niagara supply of kinetic energy that can be put to work. Water wheels are Falls. Dams, which create artificial waterfalls, are the next best way. useful for generating motion energy to grind grain or saw wood, but Dams are built on rivers where the terrain will produce an artificial lake they are not practical for generating electricity. Water wheels are too or reservoir above the dam. Today there are about 87,000 dams in the bulky and slow. United States, but less than three percent (2,200) were built specifically Hydroelectric power plants are different. They use modern turbine for electricity generation. Most dams were built for recreation, flood generators to produce electricity, just as thermal (coal, natural gas, control, fire protection, and irrigation. nuclear) power plants do, except they do not produce heat to spin the turbines. ©2019 The NEED Project Secondary Energy Infobook www.NEED.org 23  Hydropower How a Hydropower Plant Works A typical hydropower plant is a system with three parts: Hydropower Plant GENERATOR view from above MAGNETS — a power plant where the electricity is produced; COPPER COILS — a dam that can be opened or closed to control water flow; and RESERVOIR ROTATING SHAFT — a reservoir (artificial lake) where water can be stored. Intake AIL To generate electricity, a dam opens its gates to allow water from the DAM DET reservoir above to flow down through large tubes called penstocks. At GENERATOR SWITCHYARD 1 the bottom of the penstocks, the fast-moving water spins the blades PEN STO 4 CK of turbines. The turbines are connected to generators to produce 2 5 electricity. The electricity is then transported via huge transmission lines to a local utility company. 3 6 RIVER TURBINE Head and Flow 1. Water in a reservoir behind a hydropower dam flows through an intake screen, The amount of electricity that can be generated at a hydro plant is which filters out large debris, but allows fish to pass through. determined by two factors: head and flow. Head is how far the water 2. The water travels through a large pipe, called a penstock. drops. It is the distance from the highest level of the dammed water to the point where it goes through the power-producing turbine. 3. The force of the water spins a turbine at a low speed, allowing fish to pass through unharmed. Flow is how much water moves through the system—the more water that moves through a system, the higher the flow. Generally, a high- 4. Inside the generator, the shaft spins coils of copper wire inside a ring of magnets. This creates an electric field, producing electricity. head plant needs less water flow than a low-head plant to produce the same amount of electricity. 5. Electricity is sent to a switchyard, where a transformer increases the voltage, allowing it to travel through the electric grid. Storing Energy 6. Water flows out of the penstock into the downstream river. One of the biggest advantages of a hydropower plant is its ability to store energy. The water in a reservoir is, after all, stored energy. Water can be stored in a reservoir and released when needed for electricity Hydropower Production production. How much electricity do we get from hydropower today? Depending During the day when people use more electricity, water can flow on the amount of rainfall, hydro plants produce from five to ten percent through a plant to generate electricity. Then, during the night when of the electricity produced in this country. In 1997, 10.21 percent of people use less electricity, water can be held back in the reservoir. electricity came from hydropower—a historical high. However, in the last 15 years, electricity has ranged as low as 5.81 percent in 2001 Storage also makes it possible to save water from winter rains for to 7.79 percent in 2011, a recent high. In some states like Oregon, generating power during the summer, or to save water from wet years Washington, and Idaho, hydropower can account for more than half (57 for generating electricity during dry years. to 69 percent) of each state’s electricity generation. Today, there is over 79,500 megawatts of conventional hydro generating Pumped Storage Systems capacity in the United States, and a little more than 101,000 megawatts Some hydropower plants use pumped storage systems. A pumped when including pumped storage. That’s equivalent to the generating storage system operates much like a public fountain does; the same capacity of 80 large nuclear power plants. The biggest hydro plant in water is used again and again. the U.S. is located at the Grand Coulee Dam on the Columbia River in northern Washington State. The U.S. also gets some hydropower At a pumped storage hydropower plant, flowing water is used to make generated electricity from Canada. Some New England utilities buy this electricity and then stored in a lower pool. Depending on how much imported electricity. electricity is needed, the water may be pumped back to an upper pool. Pumping water to the upper pool requires electricity so hydro plants What does the future look like for hydropower? The most economical usually use pumped storage systems only when there is peak demand sites for hydropower dams in the U.S. have already been developed, so for electricity. the development of new, large hydro plants is unlikely. Pumped hydro is the most reliable energy storage system used by Existing plants can be modernized with turbine and generator American electric utilities. Coal and nuclear power plants have no upgrades, operational improvements, and adding generating capacity. energy storage systems. They must turn to gas- and oil-fired generators Plus, many flood-control dams not equipped for electricity production when people demand lots of electricity. They also have no way to store could be retrofitted with generating equipment. any extra energy they might produce during normal generating periods. 24 ©2019 The NEED Project Secondary Energy Infobook www.NEED.org Hydropower for Baseload Power Demand for electricity is not steady; it goes up and down. People use U.S. Electricity Net Generation, 2017 more electricity during the day when they are awake and using electrical Natural Gas 32.24% appliances and less at night when they are asleep. People also use more electricity when the weather is very cold or very hot. Coal 29.99% Electric utility companies have to produce electricity to meet these Uranium 20.02% changing demands. Baseload power is the electricity that utilities have NONRENEWABLE to generate all the time. For that reason, baseload power should be cheap Petroleum 0.53% and reliable. Hydropower meets both of these requirements. Generating Other 0.31% electricity with hydropower is one of the cheapest ways to generate electricity in the U.S., and the fuel supply—flowing water—is always Hydropower 7.31% available. Wind 6.32% Hydro plants are more energy efficient than most thermal power plants, Biomass 1.56% RENEWABLE too. That means they waste less energy to produce electricity. In thermal power plants, a lot of energy is lost as heat. Hydro plants are about 90 Solar 1.33% percent efficient at converting the kinetic energy of the moving water Geothermal 0.40% into electricity. *Total does not equal 100% due to independent rounding. Economics of Hydropower Data: Energy Information Administration Hydropower is the cheapest way to generate electricity today. No other energy source, renewable or nonrenewable, can match it. It costs about Top Hydropower Producing States, 2017 one cent per kilowatt-hour (kWh) to produce electricity at a typical hydro plant. In comparison, it costs coal plants about four cents per kWh 1 and nuclear plants about two and one half cents per kWh to generate WASHINGTON 5 electricity. 3 MONTANA 4 OREGON Producing electricity from hydropower is cheap because, once a dam NEW YORK has been built and the equipment installed, the energy source—flowing water—is free. 2 Hydropower plants also produce power cheaply due to their sturdy CALIFORNIA structures and simple equipment. Hydro plants are dependable and long-lived, and their maintenance costs are low compared to coal or nuclear plants. One requirement may increase hydropower’s costs in the future. The procedure for licensing and relicensing dams has become a lengthy and expensive process. Many environmental impact studies must be Data: Energy Information Administration undertaken and multiple state and federal agencies must be consulted. It takes up to seven years to get a license to build a hydroelectric dam or relicense to continue operations. Hydropower has advantages, too. Hydropower’s fuel supply (flowing Hydropower and the Environment water) is clean and is renewed yearly by snow and rainfall. Furthermore, Hydropower dams can cause several environmental problems, even hydro plants do not emit pollutants into the air because they burn no though they burn no fuel. Damming rivers may permanently alter river fuel. With growing concern over greenhouse gas emissions and increased systems and wildlife habitats. Fish, for one, may no longer be able to demand for electricity, hydropower may become more important in the swim upstream. future. Hydro plant operations may also affect water quality by churning Hydropower facilities offer a range of additional benefits. Many dams up dissolved metals that may have been deposited by industry long are used to control flooding and regulate water supply, and reservoirs ago. Hydropower operations may increase silting, change water provide lakes for recreational purposes, such as boating and fishing. temperatures, and change the levels of dissolved oxygen. Some of these problems can be managed by constructing fish ladders, dredging the silt, and carefully regulating plant operations. ©2019 The NEED Project Secondary Energy Infobook www.NEED.org 25