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A REPORT EDUCATIONAL TOUR TO HYDRO ELECTRIC POWER STATIONS Submitted to Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad In Partial Fulfilment of Requirements For the award of Degree of BACHELOR OF TECHNOLOGY IN MECHANICAL ENGINEERING By SUDEEP MISHRA (07K31A0347) DEPARTMENT OF MECHANICAL ENGINEERING ROYAL INSTITUTE OF TECHNOLOGY & SCIENCE (Affiliated to Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad) Damergidda(V),Chevella (M), R.R. Dist, Andhra Pradesh 2010-2011 HISTORY OF HYDROPOWER Humans have been harnessing water to perform work for thousands of years. The Greeks used water wheels for grinding wheat into flour more than 2,000 years ago. Besides grinding flour, the power of the water was used to saw wood and power textile mills and manufacturing plants. For more than a century, the technology for using falling water to create hydroelectricity has existed. The evolution of the modern hydropower turbine began in the mid-1700s when a French hydraulic and military engineer, Bernard Forest de Bélidor wrote Architecture Hydraulique. In this four volume work, he described using a vertical-axis versus a horizontal-axis machine. During the 1700s and 1800s, water turbine development continued. In 1880, a brush arc light dynamo driven by a water turbine was used to provide theatre and storefront lighting in Grand Rapids, Michigan; and in 1881, a brush dynamo connected to a turbine in a flour mill provided street lighting at Niagara Falls, New York. These two projects used direct-current technology. Alternating current is used today. That breakthrough came when the electric generator was coupled to the turbine, which resulted in the world's, and the United States', first hydroelectric plant located in Appleton, Wisconsin, in 1882. HYDROELECTRIC POWER / HYDROELECTRICITY Hydro means "water". So, hydropower is "water power" and hydroelectric power is electricity generated using water power. Potential energy (or the "stored" energy in a reservoir) becomes kinetic (or moving energy). This is changed to mechanical energy in a power plant, which is then turned into electrical energy. Hydroelectric power is a renewable resource. In an impoundment facility (see below), water is stored behind a dam in a reservoir. In the dam is a water intake. This is a narrow opening to a tunnel called a penstock. Water pressure (from the weight of the water and gravity) forces the water through the penstock and onto the blades of a turbine. A turbine is similar to the blades of a child's pinwheel. But instead of breath making the pinwheel turn, the moving water pushes the blades and turns the turbine. The turbine spins because of the force of the water. The turbine is connected to an electrical generator inside the powerhouse. The generator produces electricity that travels over long-distance power lines to homes and businesses. The entire process is called hydroelectricity. TYPES OF HYDROPOWER PLANTS There are three types of hydropower facilities: impoundment, diversion, and pumped storage. Some hydropower plants use dams and some do not. The images below show both types of hydropower plants. Many dams were built for other purposes and hydropower was added later. In the United States, there are about 80,000 dams of which only 2,400 produce power. The other dams are for recreation, stock/farm ponds, flood control, water supply, and irrigation. Hydropower plants range in size from small systems for a home or village to large projects producing electricity for utilities. IMPOUNDMENT The most common type of hydroelectric power plant is an impoundment facility. An impoundment facility, typically a large hydropower system, 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. It may not require the use of a dam. 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. Pumped storage hydro-electricity works on a very simple principle.Two reservoirs at different altitudes are required. When the water is released, from the upper reservoir, energy is created by the downflow which is directed through high-pressure shafts, linked to turbines. In turn, the turbines power the generators to create electricity.Water is pumped back to the upper reservoir by linking a pump shaft to the turbine shaft, using a motor to drive the pump. The pump motors are powered by electricity from the National Grid - the process usually takes place overnight when national electricity demand is at its lowestA dynamic response - Dinorwig's six generating units can achieve maximum output, from zero, within 16 seconds.Pump storage generation offers a critical back-up facility during periods of excessive demand on the national grid system. SIZES OF HYDROELECTRIC POWER PLANTS Facilities range in size from large power plants that supply many consumers with electricity to small and micro plants that individuals operate for their own energy needs or to sell power to utilities. Large hydropower Although definitions vary, the U.S. Department of Energy defines large hydropower as facilities that have a capacity of more than 30 megawatts. Small hydropower Although definitions vary, DOE defines small hydropower as facilities that have a capacity of 100 kilowatts to 30 megawatts. Microhydropower A microhydropower plant has a capacity of up to 100 kilowatts. A small or microhydroelectric power system can produce enough electricity for a home, farm, ranch, or village. TURBINES INSTALLATION LAYOUT OF HYDROELECTRIC POWER PLANTS Hydroelectric power plants convert the hydraulic potential energy from water into electrical energy. Such plants are suitable were water with suitable head are available. The layout covered in this article is just a simple one and only cover the important parts of hydroelectric plant.The different parts of a hydroelectric power plant are (1) Dam Dams are structures built over rivers to stop the water flow and form a reservoir.The reservoir stores the water flowing down the river. This water is diverted to turbines in power stations. The dams collect water during the rainy season and stores it, thus allowing for a steady flow through the turbines throughout the year. Dams are also used for controlling floods and irrigation. The dams should be water-tight and should be able to withstand the pressure exerted by the water on it. There are different types of dams such as arch dams, gravity dams and buttress dams. The height of water in the dam is called head race. (2) Spillway A spillway as the name suggests could be called as a way for spilling of water from dams. It is used to provide for the release of flood water from a dam. It is used to prevent over toping of the dams which could result in damage or failure of dams. Spillways could be controlled type or uncontrolled type. The uncontrolled types start releasing water upon water rising above a particular level. But in case of the controlled type, regulation of flow is possible. (3) Penstock and Tunnel Penstocks are pipes which carry water from the reservoir to the turbines inside power station. They are usually made of steel and are equipped with gate systems.Water under high pressure flows through the penstock. A tunnel serves the same purpose as a penstock. It is used when an obstruction is present between the dam and power station such as a mountain. (4) Surge Tank Surge tanks are tanks connected to the water conductor system. It serves the purpose of reducing water hammering in pipes which can cause damage to pipes. The sudden surges of water in penstock is taken by the surge tank, and when the water requirements increase, it supplies the collected water thereby regulating water flow and pressure inside the penstock. (5) Power Station Power station contains a turbine coupled to a generator. The water brought to the power station rotates the vanes of the turbine producing torque and rotation of turbine shaft. This rotational torque is transfered to the generator and is converted into electricity. The used water is released through the tail race. The difference between head race and tail race is called gross head and by subtracting the frictional losses we get the net head available to the turbine for generation of electricity. NATIONAL HYDROELECTRIC POWER CORPORATION NHPC Limited (Formerly National Hydroelectric Power Corporation), A Govt. of India Enterprise, was incorporated in the year 1975 with an authorised capital of Rs. 2000 million and with an objective to plan, promote and organize an integrated and efficient development of hydroelectric power in all aspects. Later on NHPC expanded its objects to include other sources of energy like Geothermal, Tidal, Wind etc. Market Value At present, NHPC is a schedule 'A' Enterprise of the Govt. of India with an authorized share capital of Rs. 1,50,000 Million . With an investment base of over Rs. 2,20,000 million Approx. In 2009-2010 NHPC made a profit after tax of Rs2090 crores . A increase of 94% than the previous year profit of 1050 crores. NHPC is among the top ten companies in India in terms of investment. Department of Public Enterprise, Govt. of India recently conferred prestigious Miniratna status to NHPC. Initially, on incorporation, NHPC took over the execution of Salal Stage-I, Bairasiul and Loktak Hydro-electric Projects from Central Hydroelectric Projects Control Board.