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RENAMEDBYADMWHILEHIDDENTOALLOWDUPLICATEACCELERATORS


The Electricity
The Electricity


Delivery System
Delivery System


Petroleum
3%
Other
Renew ables
2%
Other
0%
Hydroelectric
7%
Nuclear
20%
Natural Gas
17%
Coal
51%
Electricity Generation by Fuel Source in the
United States, 2003
Source: EIA. Electric Power Annual. 2003 data.
Generation
An electric utility power station uses either a turbine, engine,
water wheel, or other similar machine to drive an electric
generator or a device that converts mechanical or chemical
energy to generate electricity.
Steam turbines, internal-
combustion engines, gas
combustion turbines, water
turbines, and wind turbines are the
most common methods to generate
electricity. Most power plants are
about 35 percent efficient. That
means that for every 100 units of
energy that go into a plant, only 35
units are converted to usable
electrical energy.
2


Most of the electricity in the United
States is produced in steam
turbines. A turbine converts the
kinetic energy of a moving fluid
(liquid or gas) to mechanical
energy. Steam turbines have a
series of blades mounted on a shaft
against which steam is forced, thus rotating the shaft connected
to the generator. In a fossil-fueled steam turbine, the fuel is
burned in a furnace to heat water in a boiler to produce steam.
2


2. EIA. ElectricityA Secondary Energy Source. http://www.eia.doe.gov/kids/
energyfacts/sources/electricity.html#Generation (Accessed December 14, 2005)
Electricity is the flow of electrical power or charge. It is a sec-
ondary energy source, which means that we get it from the con-
version of other sources of energy, including:

Coal
Natural gas
Petroleum
Nuclear energy
Hydro energy

The energy sources used to make electricity can be renewable
or non-renewable, but electricity itself is neither renewable or
non-renewable.
1


1. EIA. What is Electricity? http://www.eia.doe.gov/kids/energyfacts/sources/
electricity.html#SecondarySource (Accessed December 14, 2005).
Geothermal energy
Solar energy
Wind energy
Biomass

Source: EIA. Electricity Basics 101. http://www.eia.doe.gov/basics/
electricity_basics.html (Accessed December 13, 2005).
Electricity Basics


www.electricity.doe.gov








February 2006
Did you know?

According to the EIA, 281 gi-
gawatts of new generating
capacity will be needed by
2025 to meet the growing de-
mand for electricity. This is
equivalent to 937 new 300-
megawatt power plants. A substation is a high-voltage electric system facility. It is
used to switch generators, equipment, and circuits or lines in
and out of a system. It also is used to change AC voltages
from one level to another, and/or change alternating current
to direct current or direct current to alternating current. Some
substations are small with little more than a transformer and
associated switches. Others are very large with several
transformers and dozens of switches and other equipment.
5

There are four main types of substations:
6


Step-up transmission substationsreceive electric
power from a nearby generating facility and use a large
power transformer to increase the voltage for
transmission to distant locations.


Step-down transmission substationsare located at
switching points in an electrical grid. They connect
different parts of a grid and are a source for
subtransmission lines or distribution lines. This
substation can change a transmission voltage to a
subtransmission voltage, usually 69 kV.


Distribution substationsare located near to the end-
users. Distribution substation transformers change the
transmission or subtransmission voltage to lower levels
for use by end-users. Typical distribution voltages vary
from 34,500Y/19,920 volts to 4,160Y/2400 volts.


Underground distribution substationsare also
located near to
the end-users.
Distribution
substation
transformers
change the
subtransmission
voltage to lower
levels for use
by end-users.

5. OSHA. www.osha.gov (Accessed 11/23/05).
6. ibid.
Type and Number of Equipment Installed at All U.S.
Substations
Equipment
Total Number Installed
Autotransformer 12,151
Oil Circuit Breaker
193,586
Oil Circuit Recloser
7,004
Reactor
422
Transformer 63,797
Vacuum Circuit
Breaker
338
Vacuum Circuit
Recloser
169
Voltage Regulator
25,443
Note: Totals for all substations within the utility industry based
on the assumption of 50,000 total and extrapolated from
Entergy data.
Source: EPA, Data on Oil Filled and Process Equipment, Sept. 2004.
Operational Electrical Equipment Device Breakdown for
Substations by Volume of Oil Contained in In-service
Equipment
Device Volume Range
(gallons)
Number of Pieces of
Electrical Equipment
< 54
46,245
55-100
60,253
101-500 55,401
501-1,500
36,709
1,501 5,000
61,097
5,001 - 10,000
32,869
10,001 15,000
6,878
15,001 20,000
3,333
> 20,000
1,435
Note: Totals for substations within the utility industry based on the
assumption of 50,000 total and extrapolated from Entergy data.
Source: EPA, Data on Oil Filled and Process Equipment, Sept. 2004.
In the U.S., there are 10,287 transmission substations and 2,179
distribution substations.
7
Transmission substations use trans-
formers to convert a generators voltage up to 155,000 to
765,000 volts for long distance transmission in order to reduce
transmission line losses. The distribution substation steps
power down the voltage to distribution levels and splits it into
many directions.

Substations are critical component of our distribution system,
and a loss of only 4% of transmission substations would result
in a 60% loss of connectivity.
8


7. Structural Vulnerability of the North American Power Grid.
http://arxiv.org/
PS_cache/cond-mat/pdf/0401/0401084.pdf
.
8. Midwest Research Institute. Research Team Finds US Power Grids Vulnerable.
http://
www.trackingterrorism.com/default.asp?dismode=article&foobar=1029&artid=99
.
Generation
Transmission
Distribution
www.electricity.doe.gov








February 2006
Substations Transmission lines carry
electric energy from one point
to another in an electric power
system. They can carry
alternating current (AC) or
direct current (DC) or a system
can be a combination of both.
3


Also, electric current can be carried by either overhead
or underground lines. The main characteristics that
distinguish transmission lines
from distribution lines are that
they are operated at relatively
high voltages, they transmit
large quantities of power, and
they transmit the power over
large distances.
4


3. OSHA. www.osha.gov (Accessed
December 13, 2005).
4. ibid.
Circuit Miles of Electric Transmission Lines in Service by Division and Voltage Level
(Preliminary 2003 data)


Circuit Miles Voltage Level (Kilovolts)
Division
<132
132-143 144-188 189-253 254-400 401-600 >600
Total
Per
Division
% that is
Shareholder
-Owned
New England
(ME, NH, VT, MA, RI, CT)
13,092 271 -- 342 1,904 536 -- 16,145 97.4
Middle Atlantic
(NY, NJ, PA)
23,888
3,948
--
5,581
3,940
2,264
351
39,972
90.8
East North Central
(OH, IN, IL, MI, WI)
42,781 24,991 2,461 1,548 16,338 -- 1,218 89,336 72.7
West North Central
(MN, IA, MO, ND, SD, NE, KS)

69,464
1,998
9,560
8,642
8,990
1,124
--
99,778
45.1
South Atlantic
(DE, MD, DC, VA, WV, NC, SC,
GA, FL)
48,587 8,505 491 23,167 411 5,948 644 87,753 80.5
East South Central
(KY, TN, AL, MS)
29,117
2,237
14,014
3,445
1,003
3,270
258
53,343
42.1
West South Central
(AR, LA, OK, TX)
34,384 32,482 3,105 3,787 13,764 1,869 -- 89,392 71.8
Mountain
(MT, ID, WY, CO, NM, AZ, UT,
NV)
41,195
5,008
2,002
14,651
10,332
7,056
1,687
81,930
58.6
Pacific
(WA, OR, CA)
39,511 588 571 22,687 2,876 10,803 557 77,593 61.0
Alaska and Hawaii
(AK, HI)
1,749
505
--
198
209
--
--
2,660
44.1
Total by Voltage Level 343,768
80,533
32,204 84,048 59,767 32,870 4,715 637,902
65.2
Source: Edison Electric Institute. EEI Statistical Yearbook Based on 2004 Data. Aug. 2005.
Ownership of High-Voltage Transmission Lines in the U.S.,
1994
Source: EIA The Changing Structure of the Electric Power Industry 2000: An
Update, October 2000.
Miles of AC and DC Transmission Lines in the U.S. in 2002
Voltage (kV)
Miles
Voltage (kV)
Miles
AC

DC

230
76,762
250-300
930
345
49,250
400
852
500
26,038
450
192
765
2,453
500
1,333
Total AC
154,503
Total DC
3,307
Total AC/DC 157,810
Source: DOE National Transmission Grid Study, May 2002.
www.electricity.doe.gov








February 2006
Transmission
Generation
Transmission
Distribution Long distance transmission is typically
done with overhead lines at voltages of 110
to 765 kV. Many of American Transmis-
sion Companys existing overhead trans-
mission lines were built during the 1950s
and 1960s, when the common structure
design was self-supporting steel lattice tow-