Turbine: A turbine is a type of engine that can extract energy from a fluid, such as water, steam, air, or combustion gases. It has a series of blades, and thefluid goes in one end, pushing the blades and
causing them to spin.
Turbine Generator
A generator is a device that converts mechanical energy into electrical energy. The process is based on the relationship between magnetism and electricity. In 1831, scientist Michael Faraday discovered that when a magnet is moved inside a coil of wire, electrical current flows in the wire.
A typical generator at a power plant uses an electromagnet — a magnet produced by electricity — not a traditional magnet.
The generator has a series of insulated coils of wire that form a stationary cylinder. This cylinder surrounds a rotary electromagnetic shaft. When the electromagnetic shaft rotates, it induces a small electric current in each section of the wire coil. Each section of the wire becomes a small, separate electric conductor. The small currents of individual sections are added together to form one large current. This current is the electric power that is transmitted from the power company to the consumer.
An electric utility power station uses either a turbine , engine, a water wheel, or another similar machine to drive an electric generator — a device that converts mechanical or chemical energy to electricity. Steam turbines, internal-combustion engines, gas combustion turbines, water turbines, and wind turbines are the most common methods to generate electricity.
Steam turbine power plants powered by coal and nuclear energy produce about 70% of the electricity used in the United
States. These plants are about 35% efficient. That means that for every 100 units of primary heat energy that go into a plant, only 35 units are converted to useable electrical energy.
Most of the electricity in the United States is produced using steam turbines.
A turbine converts the kinetic energy of a moving fluid (liquid or gas) to mechanical energy. In a steam turbine, steam is forced against a series of blades mounted on a shaft, thus rotating the shaft connected to the generator. The generator, in turn, converts its mechanical energy to electrical energy based on the relationship between magnetism and electricity.
In steam turbines powered by fossil fuels, such as coal, petroleum (oil), and natural gas, the fuel is burned in a furnace to heat water in a boiler to produce steam.

In 2012, coal was used for about 37% of the 4 trillion killowatthours of electricity generated in the United States.
Natural gas, in addition to being burned to heat water for steam, can also be burned to produce
Combustion:
Burning – reacting with oxygen to
produce heat hot combustion gases that pass directly through a turbine, spinning the turbine's blades to generate electricity. Gas turbines are commonly used when electricity utility usage is in high demand. In 2012, 30% of the U.S. electricity was fueled by natural gas.
Petroleum can be burned to produce hot combustion gases to turn a turbine or to make steam to turn a turbine. Residual fuel oil, a product refined from crude oil, is often the petroleum product used in electric plants that use petroleum to make steam. Petroleum was used to generate less than 1% of all electricity in the United States in 2012.
Nuclear power is a method in which steam is produced by heating water through a process called nuclear fission. In a nuclear power plant, a reactor contains a core of nuclear fuel, primarily uranium. When atoms of uranium fuel are hit by neutrons, they fission (split) releasing heat and more neutrons. Under controlled conditions, these other neutrons can strike more uranium atoms, splitting more atoms, and so on. Thereby, continuous fission can take place, creating a chain reaction releasing heat. The heat is used to turn water into steam, that, in turn, spins a turbine that generates electricity. Nuclear power was used to generate about 19% of all U.S. electricity in 2012.
Hydropower, the source for almost 7% of U.S. electricity generation in 2012, is a process in which flowing water is used to spin a turbine connected to a generator. There are two basic types of hydroelectric systems that produce electricity. In the first system, flowing water accumulates in reservoirs created by dams. The water falls through a pipe called a penstock and applies pressure against the turbine blades to drive the generator to produce electricity.
In the second system, called run-of-river, water is diverted from a river using a relatively low dam or weir into penstocks and turbines. The dam does not store a large volume of water in a reservoir. Run-of-river power plants are more dependent on river flows than hydro plants with reservoirs for storing water which can produce electricity even when natural river flows are low.
Biomass is material derived from plants or animals (i.e. biogenic) and includes lumber and paper mill wastes; food scraps, grass, leaves, paper, and wood in municipal solid waste (garbage); and forestry and agricultural residues such as wood chips, corn cobs, and wheat straw. These materials can be burned directly in steam-electric power plants, or converted to gas that can be burned in steam generators, gas turbines, or internal combustion engine-generators. Biomass accounted for about 1% of the electricity generated in the United States in 2012.
Wind power is produced by converting wind energy into electricity. Electricity generation from wind has increased significantly in the United States since 1970, but wind power remains a small fraction of U.S. electricity generation, about
3% in 2012.
Geothermal power comes from heat energy buried beneath the surface of the earth. In some areas of the United States, enough heat rises close to the surface of the earth to heat underground water into steam, which can be tapped for use at steam-turbine plants. This energy source generated less than 1% of the electricity in the United States in 2012.
Solar power is derived from energy from the sun. There are two main types of technologies for converting solar energy to electricity: photovoltaic (PV) and solar-thermal electric. PV conversion produces electricity directly from sunlight in a photovoltaic (solar) cell. Solar-thermal electric generators concentrate solar energy to heat a fluid and produce steam to drive turbines. In 2012, less than 1% of the U.S. electricity generation was from solar power.

Electric power is generated at power plants and then moved to substations by transmission lines — large, high-voltage power lines. In the United States, the network of nearly 160,000 miles of high voltage transmission lines is known as the
"grid."
A local distribution system of smaller, lower-voltage distribution lines moves power from substations and transformers to customers.
Electric power generation, transmission, and distribution diagram
In the United States, fossil fuels (mainly coal, oil, and natural gas), materials that come from plants (biomass), and municipal and industrial wastes are used to generate most of the electricity we use; about 69% in 2012. Emissions that result from the combustion of these fuels include:
 Carbon dioxide (CO2)
 Carbon monoxide (CO)
 Sulfur dioxide (SO2)
 Nitrogen oxides (NOX)
 Particulate matter (PM)
 Heavy metals such as mercury
Nearly all combustion byproducts have negative impacts on the environment and human health:
 Carbon dioxide is a greenhouse gas and a source of global warming.1
 SO2 causes acid rain, which is harmful to plants and to animals that live in water, and it worsens or causes respiratory illnesses and heart diseases, particularly in children and the elderly.
 NOX contributes to ground level ozone, which irritates and damages the lungs.
 PM results in hazy conditions in cites and scenic areas, and, along with ozone, contributes to asthma and chronic bronchitis, especially in children and the elderly. Very small, or “fine PM” is also thought to cause emphysema and lung cancer.
 Heavy metals such as mercury can be hazardous to human and animal health.

Power plants are required to meet standards that limit the amounts of some of the substances that they release into the air.
There are different ways that power plants meet these standards:
 Coal-fired plants can use coal that is low in sulfur content. Coal can also be pre-treated and processed to reduce the types and amounts of undesirable compounds in combustion gases.
 Particulate matter emissions are controlled with devices that clean the combustion gases that exit the power plant: o “Bag-houses” use large filters o Electrostatic precipitators use charged plates o Wet scrubbers use a liquid solution
 SO2 emissions are controlled by wet and dry scrubbers, which involves mixing lime in the fuel (coal) or by spraying a lime solution into the combustion gases. Fluidized bed combustion can also be used to control SO2.
 NOX emissions can be controlled by several different techniques and technologies, such as low NOX burners during the combustion phase or selective catalytic and non-catalytic converters during the post combustion phase.
The coarse solid residue that results from the burning solid fuels is called ash. The largest particles collect at the bottom of the boiler ("bottom ash") and are removed and quenched with water. Smaller and lighter particulates ("fly ash") are collected in air emission control devices, and are usually mixed with the bottom ash. The resulting "sludge," which contains all the hazardous materials that were captured by the pollution control devices, may be stored in retention ponds, sent to landfills, or sold for use in making concrete blocks or asphalt. Many coal-fired power plants have very large sludge ponds.
Several of these ponds have burst and caused extensive damage and pollution downstream of the pond.
Greenhouse gases contribute to the “greenhouse” effect. Scientists know with virtual certainty that increasing greenhouse gas concentrations tend to warm the planet.
Power plants that burn fossil fuels and materials made from fossil fuels and some geothermal power plants are the sources of about 40% of total U.S. carbon dioxide (CO2) emissions.
Nuclear power plants are not a source of greenhouse gases or other emissions, but they do produce two kinds of radioactive waste:
 Low-level radioactive waste — This includes items that have become contaminated with radioactive material, such as clothing, wiping rags, mops, filters, reactor water treatment residues, and equipment and tools. Low-level waste is stored at nuclear power plants until the radioactivity in the waste decays to a level where it is allowed to be disposed of as ordinary trash or it is sent to a low-level waste disposal site.
 Spent (used) nuclear fuel — The spent fuel assemblies are highly radioactive and must initially be stored in specially designed pools resembling large swimming pools (water cools the fuel and acts as a radiation shield) or in specially designed dry storage containers. An increasing number of reactor operators now store their older spent fuel in dry storage facilities using special outdoor concrete or steel containers with air cooling.