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Base Load
The minimum level of electric power demand of a utility, region, or
utility customer, generally expressed in units of kilowatts or
megawatts.
Base-Load Unit
An electric power plant, or generating unit within a power plant,
that is normally operated continuously to meet the base load of a
utility or of a larger area operated by an ISO.
California Independent System Operator (CAISO) or (ISO)
The Independent System Operator operates the transmission
systems owned by Pacific Gas and Electric (PG&E), Southern
California Edison, and San Diego Gas & Electric (SDG&E). The
abbreviation ISO sometimes refers to the California ISO, and
sometimes to refers to any Independent System Operator (also
see Independent System Operator).
Capacity Factor
A measure of the degree to which the capacity of a generating
unit is being used during a specified period of time. Expressed as
a ratio of the electric energy produced during the specified period
to the electric energy the unit could have produced if it operated
at full capacity during the entire period.
Combined-Cycle Power Plant
A power plant that uses two different thermal cycles for producing electricity.
The first cycle burns a fuel inside a gas turbine, and the gas turbine drives an
electric generator. The hot air coming out of the gas turbine is used to turn
water into steam, and the steam turns a second electric generator. Combined
cycle power plants are the most efficient technology currently available for
turning a fuel into electricity. They can use a wide variety of liquid and gaseous
fuels, but almost all of the combined cycle power plants in the United States
burn natural gas.
Combustion Turbine Power Plant
A combustion turbine burns a fuel to produce a large volume of hot air, which
then goes through a series of precision fan blades, which convert the energy of
the hot air into rotation of a shaft. The shaft, in turn, is connected to an
electric generator. The technology is closely related to the jet engines used on
airplanes. Combustion turbine power plants can be built at a lower cost than
other large power plants, but they are relatively inefficient in converting fuel
into electricity.
Distribution
Delivery of electric energy to customers. Customers are connected to power
lines that operate at lower voltages than transmission lines. Transmission lines
carry electric power over longer distances.
Distributed Generation (DG)
Generation of electricity by small-scale power plants located near the electric
loads they serve. The term generally is used to refer to power plants that are
small enough to be connected to distribution instead of transmission.
Depending on the size of nearby loads and the capacity of the distribution line
to which it is connected, the maximum size of distributed generation can vary
from a few hundred kW to 5 MW. The smallest DG units commercially available
today can produce 30 kW.
Electric Generator
A device that converts another form of energy into electric energy. Common
types of electric generators spin an electromagnet on a shaft, which induces
electric voltage in coils of wire surrounding the electromagnet. The shaft is
driven by an engine attached to it, or by a turbine that is part of the electric
generator. A turbine has blades attached to the shaft, which are turned by the
force of steam, hot gasses or wind.
Generation
Conversion of other forms of energy into electric energy. Forms of energy that
are commonly converted into electricity include natural gas, oil, diesel fuel,
falling water, geothermal steam, nuclear fuel, sunshine, and biomass materials
such as municipal solid waste and lumber mill residuals.
Gigawatt (GW)
1,000 megawatts or 1 billion watts.
Gigawatt-Hour (GWh)
1,000 megawatt-hours or 1 billion watt-hours.
Independent System Operator (ISO)
An organization that operates an electric-transmission system that it does not
own. Usually, the transmission system it operates includes transmission lines
owned by more than one electric utility. An ISO's responsibilities include
insuring that there is enough generation available at all times so that if one
generating plant fails, others will pick up the load immediately without
interrupting service to customers.
Electric transmission systems do not have valves that can control the flow of
electricity over the transmission lines. Therefore, an ISO operates the
transmission system by controlling the amount of electricity that is generated
at each point in the transmission system so that the transmission lines do not
become over loaded. The abbreviation ISO sometimes refers to any ISO, and
sometimes to refers to the California Independent System Operator.
Kilowatt (kW)
A kilowatt is equal to 1,000 Watts.
Kilowatt-Hour (kWh)
A kilowatt-hour is 1,000 watt-hours. A household that uses an average of one
kWh for every hour over an average month would be billed by the utility for 730
kWh for that average month.
Load
A term that is sometimes used to refer to the cumulative electric demand of a
geographic area, such as a city or an electric utility. It is measured in
megawatts.
Megawatt (MW)
1,000 kilowatts or 1,000,000 watts.
Megawatt-Hours (MWh)
1,000 kilowatt-hours or 1,000,000 watt-hours.
Municipal Solid Waste (MSW)
Waste material that is collected from homes and businesses. Waste materials
from industrial processes that are not considered safe to place into landfills are
not allowed to become MSW, and recycled materials are not included in MSW.
MSW is referred to in common parlance as garbage.
Peak Load
The maximum demand for electric energy from all of the customers of a utility
or over a geographic area. It usually refers to the largest demand experienced
during a calendar year, though it can be the largest demand for a month, or
other specified period.
Reserve Margin
The difference between the peak load and the portion of electric resources that
are expected to be able to operate during the peak load of a utility or
geographic area. Reserve margin is expressed in megawatts or the percentage
by which the available portion of the resources exceeds the peak load.
Resources
A term that refers to the cumulative capacity of a set of electric power plants.
The set of power plants may be in a defined geographic area, such as the Bay
Area; power plants owned by a single party such as an electric utility; or all of
the power plants available to meet the load of a utility or ISO, regardless of
their location on the transmission system or ownership of the power plants.
Substation
An assemblage of equipment within a fenced area that switches, changes or
regulates voltage in electric transmission and distribution systems. Among
other things, substations are used to increase the voltage of electricity so that
it can be transported efficiently over long distances and reduce the voltage so
that it can be delivered in a practical and economical manner to homes and
businesses.
Transmission
The transportation of electricity over high-voltage power lines. The definition of
high-voltage varies from one utility to another. PG&E defines all power lines
and substations that operate at 50,000 volts (50 kV) or higher as transmission
lines. At Alameda Power & Telecom and in Southern California, only power
lines and substations that operate at more than 150,000 volts (150 kV) are
part of the transmission system. Power lines and substations that operate at
lower voltages than transmission are part of electric distribution.
Watt (W)
Watts are a basic unit of measure of electric power, or the rate of doing electric
work. Light bulbs and appliances are rated by the amount of electric power they
consume measured in watts. For instance, a 100-watt light bulb on a 110-volt
electric circuit uses 0.9 amps of current to produce 100 watts of work. A
comparison with other measures of work is that one horsepower equal 746-
watts.
Watt-Hour (Wh)
The basic unit of measure for consumption of electric energy. One watt-hour is
one watt of electricity used for a period of one hour.
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Contact Information:
Email: info@alamedapt.com
Internet: www.alamedapt.com
2000 Grand Street
P.O. Box H
Alameda, CA 94501-0263
Phone 510-748-3900
Fax 510-748-3975
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