Transcript Introduction to Energy Generation and Distribution

The History of Electricity
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Electrical Discoveries
•Natural occurrences of electricity:
•Lightning
•Static-amber rods rubbed with cat fur
•Electric fish (electric eels, electric catfish, others)
•Nerve operation
•Brain activity
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Electrical Discoveries
•Numerous scientists from 1600’s on started treating this as
more than a curiosity
•Benjamin Franklin’s kite experiment in 1752 proved
lightning was electricity
•Luigi Galvani in 1791 proved that electricity is what makes
nerves work
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Ben Franklin
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Electrical Inventions
•Electromagnetism united electricity and magnetism in
1819 (Orsted and Ampere)
•Faraday invented the electric motor in 1821
•1830’s: several inventors created the telegraph
•Alexander Graham Bell invented the telephone in 1876
•Thomas Edison invented the electric light bulb in 1879
•Nikola Tesla invented Alternating Current
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Thomas Edison
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Nikola Tesla
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Electrical Inventions
•Whale oil, “town gas”, kerosene primary means of
providing gas lights for many years prior to electricity
•Widespread use of electricity to operate lights
•Batteries
•Electric vehicles
•Enhanced and larger electric motors: AC and DC
•Large generating systems: AC and DC
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The Industrial Revolution
•2nd half of the 1700’s through the 1800’s
•Mechanization transformed modern society
•Large industries sprang up, many powered by horses, then
by steam engines
•Agrarian farm life rapidly declined as farmers went to work
in factories to earn better wages
•Textiles, iron manufacturing, invention of concrete , all
spurred growth in industrial systems
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The Industrial Revolution
•Prior to steam power, horse power and water power were
the dominant forms of primary power for industry
•Most fast-moving water was in New England states
•Development of steam power opened up other areas of US
for industrial development
•Transportation changed dramatically thanks to steampowered trains
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Steam Locomotive
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The War of the Currents: AC vs. DC
•Edison promoted his Direct Current(DC) as the only “safe”
way to deliver electricity to large populations
•Westinghouse promoted Alternating Current (AC) as the
only way to transport electricity over long distances
•DC commercial power canonly be transported a few miles.
•Edison invented large scale DC generators
•Westinghouse bought patents for AC from Tesla
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George Westinghouse
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The War of the Currents: AC vs. DC
•Edison started General Electric, later lost it to bankers
•1882: Edison builds Pearl Street DC station in NYC
•1894: Niagra Falls Power Company powered Buffalo, NY
•Westinghouse/Tesla team eventually won the war of the
currents
•Today AC electricity can be transported 1000’s of miles by
increasing the voltage at the generator to extreme levels
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Electrical Distribution Begins
•Various frequencies of AC were tried. Settled on 60Hz
•60Hz was used because of easy timing with clocks.
•Also any frequency above about 40-50Hz makes flicker-
free lighting: important in AC systems
•Also higher frequencies would require faster spinning
generators, creating mechanical challenges
•1893: Westinghouse/Tesla system demonstrated AC at
Chicago Exposition
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1900’s: Electrical Distribution Begins
•Once an electrical power generating systems begins, all
generators tied to that “grid” must be same frequency and phase
•When loads increase demand for electricity, more generators
must be added.
•Numerous safeguards must be built in for safety and isolation of
failures
•First distribution systems were in cities where it was economical
for the electric utilities to build and sell power to large customer
bases
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REA and TVA
•Rural Electrification Administration
•Tennessee Valley Authority
•Great Depression of 1929
•Public power vs. private (investor-owned) utilities hotly
contested during 1920’s
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REA and TVA
•Prior to 1933, privately owned utilities refused to
extend their service to rural areas, claiming lack of
profitability
•Private power companies set rural rates 4 times higher than
city rates
•Obviously, this was not perceived as a fair treatment of
rural families
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TVA
•Tennessee Valley Authority
•Federally-owned private corporation
•Established in May 1933 to provide:
•Flood control
•Navigation of waterways
•Affordable electricity for rural communities
•Fertilizer for more effective, productive farming
•Economic development
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TVA
•Cover s most of Tennessee, parts of Alabama, Mississippi,
Kentucky, a few other SE States.
•Nation’s largest public power company
•FDR campaigned on this issue during Presidential race: 1932
•Nebraska Senator George Norris from McCook, NE partnered
with Franklin Roosevelt to help establish public power entities
•Red=dams; purple=nuclear power; yellow=fossil power
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©
© 2010
2010 Board
Board of
of Regents
Regents University
University of
of Nebraska
Nebraska
REA
•Rural Electrification Administration established 1935
•Made loans available to local electric cooperatives to compete
with big power companies
•1930: 10% of rural homes had electricity
•1940: 90% of rural homes had electricity
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REA
•PUHCA (Public Utility Holding Company Act): 1935
•Regulate electric utilities
•Get control of private utilities
•REA has been reorganized (1994) and is now called RUS (Rural Utilities
Service)
•RUS is an agency of the United States Dept of Agriculture
•RUS Tasked with providing to rural areas the following utilities:
•Electricity
•Telephone
•Water
•Sewer
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US Electrical Distribution Today
•Three separate grids:
•Eastern interconnection
•Western interconnection
•Texas interconnection (ERCOT: Electric Reliability Council
of Texas)
•Alaskan and some Canadian grids separate from the
three main USA grids
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US Electrical Distribution Today
•Reliability of each grid is critical
•Each grid started independently at different times
•Very little interconnection between the three grids
•60 Hz phase is different in each grid
•Can not directly connect grids together
•Must convert 60Hz AC to DC, then back to AC at the
receiving grid’s phase
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US Electrical Distribution Today
•Utility generators create 2300 to 30,000 volts
•A transformer steps this voltage up to a higher voltage for long-
distance transmission
•When voltage is stepped up, current is stepped down
•Some power is lost in the transformation of voltage/current
•Numerous high voltage systems in use across North America
•765,000 volts
•138,000 volts
500,000 volts
115,000 volts
345,000 volts
230,000 volts
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US Electrical Distribution Today
•At various locations, sub-stations reduce the
transmission voltage to more usable levels
•4000 volts – 69,000 volts
•Final users get their power at lower voltages of 120-480
volts.
•Transformers are used to change voltage levels, up and
down. Only AC power can do this
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Electrical Distribution System
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