Presentation on theme: "Noor Shazliana Aizee Abidin. Hydropower 1700 ’ s ~ Early 1800 ’ s For more than a century, the technology for using falling water to create hydroelectricity."— Presentation transcript:
Noor Shazliana Aizee Abidin
Hydropower 1700 ’ s ~ Early 1800 ’ s 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 B é lidor wrote Architecture Hydraulique.
In this four volume work, he described the working of a vertical-axis versus a horizontal-axis machine. Hydro-electric power stations use the energy from falling water to make electricity. Running water is a very powerful source of energy. For hundreds of years it has been used to drive machinery, grind flour, and saw lumber.
Late 1800,s Michigan's Grand Rapids Electric Light and Power Company. Niagara Falls, New York. Fox River in Appleton, Wisconsin
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 first hydroelectric plant located in Appleton, Wisconsin, in 1882.
Mid-1900 ’ s Industrial age New technology Better Construction Bigger Budgets
By the mid 1900s, hydroelectric power accounted for more than 40 percent of the United States' supply of electricity. During the industrial revolution the need for energy was provided by the increasing number of dams, which supplied the production lines, businesses and homes.
At the peak utility hydropower provided 75% of the total US energy requirement. In the later half of that century as the country energy demand grew hydropower was replaced and energy needs were more and more being meet by fossil fuels and nuclear.
Currently 1/10 of electricity, US. 20% World electricity
With the increase in development of other forms of electric power generation, hydropower's percentage has slowly declined and today provides around 10% of the United States' electricity. But current Dams account for 19% of electricity generated worldwide, and 24 countries generate more than 90 percent of their power from dams. There are 45,000 large dams in the world, most built in the 1970s. China and India contain half the world's dams.
How Hydropower Works Hydropower is using water to power machinery or make electricity. Water constantly moves through a vast global cycle, evaporating from lakes and oceans, forming clouds, precipitating as rain or snow, then flowing back down to the ocean.
The energy of this water cycle, which is driven by the sun, can be tapped to produce electricity or for mechanical tasks like grinding grain. Hydropower uses a fuel—water—that is not reduced or used up in the process. Because the water cycle is an endless, constantly recharging system, hydropower is considered a renewable energy.
When flowing water is captured and turned into electricity, it is called hydroelectric power or hydropower. 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.
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. 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.
An impoundment hydropower plant dams water in a reservoir.
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. The Tazimina project in Alaska is an example of a diversion hydropower plant. No dam was required.
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 Energy control- produce power on demand 70-80% efficency Net electricity consumers Can be PV and wind powered
Sizes of Hydroelectric Power Plants Large Hydropower Although definitions vary, large hydropower as facilities that have a capacity of more than 30 megawatts. Small Hydropower Small hydropower as facilities that have a capacity of 100 kilowatts to 30 megawatts.
Large Hydro-systems Defined as greater than 30 megawatts by Department of Energy Hoover dam- (1300 MW) Largest in World Venezuela (10,000MW) China- 18,600 MW (2009)
Small Hydro-systems DOE 100kw – 30mw Industries, towns Thailand (9mw) Could power several industries or a small town
Micro Hydropower A micro hydropower plant has a capacity of up to 100 kilowatts. A small or micro-hydroelectric power system can produce enough electricity for a home, farm, ranch, or village.
Micro-hydro system DOE kw Farm, home, village Increasing in #’s Today
Types of 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.
Turbines: Reaction or Impulse Depends on: head, flow, and pressure Impulse- similar to water wheel (cupped Blades) Spins in the air Reaction- used in large facilities (Blades similar to boat propeller) Submerged in water
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.
Impulse-type Turbine High-head use- (Vertical drop > 10m) High pressure (PSI)
Pelton A pelton wheel has one or more free jets discharging water into an aerated space and impinging on the buckets of a runner. Draft tubes are not required for impulse turbine since the runner must be located above the maximum tailwater to permit operation at atmospheric pressure.
Cross-Flow A cross-flow turbine is drum-shaped and uses an elongated, rectangular-section nozzle directed against curved vanes on a cylindrically shaped runner. It resembles a "squirrel cage" blower. The cross- flow turbine allows the water to flow through the blades twice.
The first pass is when the water flows from the outside of the blades to the inside; the second pass is from the inside back out. A guide vane at the entrance to the turbine directs the flow to a limited portion of the runner. The cross-flow was developed to accommodate larger water flows and lower heads than the Pelton.
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.
Propeller A propeller turbine generally has a runner with three to six blades in which the water contacts all of the blades constantly. Picture a boat propeller running in a pipe. Through the pipe, the pressure is constant; if it isn't, the runner would be out of balance. The pitch of the blades may be fixed or adjustable. The major components besides the runner are a scroll case, wicket gates, and a draft tube.
There are several different types of propeller turbines: Bulb turbine The turbine and generator are a sealed unit placed directly in the water stream. Straflo The generator is attached directly to the perimeter of the turbine. Tube turbine The penstock bends just before or after the runner, allowing a straight line connection to the generator.
Kaplan Both the blades and the wicket gates are adjustable, allowing for a wider range of operation. Kaplan hydropower turbine Credit: GE Energy
Francis A Francis turbine has a runner with fixed buckets (vanes), usually nine or more. Water is introduced just above the runner and all around it and then falls through, causing it to spin. Besides the runner, the other major components are the scroll case, wicket gates, and draft tube. Francis hydropower turbine Credit: GE Energy
Hydropower – Pros and Cons Current hydropower technology, while essentially emission-free, can have undesirable environmental effects, such as fish injury and mortality from passage through turbines, as well as detrimental effects on the quality of downstream water.
Fish Passage Fish populations can be impacted if fish cannot migrate upstream past impoundment dams to spawning grounds or if they cannot migrate downstream to the ocean. Upstream fish passage Fish ladders or elevators trucks Downstream fish passage 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.
Water Quality and Flow Hydropower plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian habitats and is addressed using various aeration techniques. Maintaining minimum flows of water downstream of a hydropower installation is also critical for the survival of riparian habitats.
Environmentally Friendly Turbines Environmentally friendly turbines, also called "fish friendly" turbines, aim to reduce fish mortality when passing through the turbine, while also increasing water quality by maintaining dissolved oxygen concentrations.
Pros Control of floods and water flow Generate electric cleanly and is renewable Efficiency – Energy to Electricity at 90%
Cons Disrupt natural flow patterns of the stream Fertilization of flood plain Fish migration Sediment and stratification Decommissioning and Dam removal Hydro licensing / re-licensing