ing forestry and agricultural
crops, crop processing wastes and residues, animal
manures, and landll methane gas into electricity
or thermal energy in processing plants.
BTU (British Thermal Unit) a measure of the
heat content of a substance that is burned to
produce energy; equivalent to the burning of one
match stick.
Capacity factor the value of the average power
output of a generating system compared to the
capacity rating of the system over a specied
period of time.
Co-ring using more than one fuel source to
produce electricity in a power plant. Common
combinations include biomass and coal, biomass
and natural gas, or natural gas and coal.
Concentrating solar power technologies that
capture solar energy by converting the suns light
into heat by concentrating direct radiation onto
a receiver, where it is absorbed into a uid. The
heat in the uid is transported to a heat engine
that converts the thermal energy into electricity.
District heating system local system that provides
thermal energy through steam or hot water piped
to buildings within a specic geographic area.
Used for space heating, water heating, cooling,
and industrial processes. A common application
of geothermal resources.
Distributed generation small power plants sited
at many locations, which can be used to reduce
burden on a transmission system by generating
electricity close to areas of customer need, thereby
reducing the need for transmitting electricity
during peak times.
Energy crop a plant grown with the express
purpose to be used in biomass electricity or
thermal generation.
Geothermal heat, in the form of hot water,
steam, or rocks, near the surface of the earths
crust used for direct heating and cooling, or for
electricity generation.
Geothermal heat pump device which circulates
geothermally heated uid through sealed pipes to
transfer heat from one area to another to cool or
heat an interior space.
Installed capacity amount of power that could
be generated by an energy source if operated at
its maximum capacity. Expressed in wattage,
usually kilowatts (kW) or Megawatts (MW).
kW (kilowatt) 1000 watts (see W).
kWh (kilowatt-hour) unit of energy equivalent
to one kilowatt (kW) of power expended for one
hour of time; common measurement of electricity.
Landll gas naturally occurring methane prod-
uced in landlls; can be burned in a gas turbine
to produce electricity.
Large-scale see Utility-scale.
Load amount of electricity required to meet
customer demand at any given time.
Load growth increase in the amount of consumer
demand for electricity
MW (Megawatt) 1,000,000 watts, or 1,000
kilowatts.
MWh (Megawatt-hour) 1,000 kWh.
Passive solar design construction of a building
to maximize solar heat gain in the winter and
minimize it in the summer, thereby reducing the
use of mechanical heating and cooling systems.
Peak load the amount of electricity required to
meet customer demand at its highest.
Photovoltaics (PV) devices that convert sunlight
directly into electricity using semiconductor
materials. Most commonly found on a xed or
movable panel; also called solar panels. w w w . E n e r g y A t l a s . o r g
Policy Denitions
Green Power Program an option offered
to customers by a utility to pay a premium
for a green power source (frequently wind
or solar). Usually designed to support the
development of new renewable energy
facilities above regulatory requirements.
Net Metering policy allowing customers
with their own generating units to sell
excess power back to the grid, enabling the
ow of electricity to and from the customer
through a single, bi-directional meter. Net
metering laws typically include a limit on
the size of generating units, ranging from
1 kW to more than 1,000 kW. Some utilities
require use of dual meters and sale of power
to the utility at avoided energy costs, termed
net billing.
Other rebates, loans or grant programs
offered by the state or a utility to assist in
nancing renewable energy projects.
Property tax exemption an exemption,
exclusion or credit against property taxes.
Renewable Portfolio Standard a require-
ment that a certain percentage of a utilitys
overall capacity of electricity sales be derived
from renewable resources.
Sales tax exemption an exemption from
state sales tax for the cost of renewable
energy equipment.
System Benets Charge fee implemented
to assure nancial support for renewable
energy, energy efciency and/or low-income
support programs. Typically a small charge
to all customers on the basis of electricity
consumption.
Tax incentives (personal/corporate) income
tax credits or deductions for the purchase
and/or installation of renewable energy
equipment.
Power production potential amount of electricity
that could be generated from an energy resource.
Small-scale or residential-scale a generating
facility designed to output enough electricity to
offset the needs of a residence, farm or small
group of farms; generally 250 kW or smaller.
Solar easement right expressed as an easement,
restriction, covenant or condition obtained by
the landowner for the purpose of exposure of an
active or passive solar energy system to the direct
rays of the sun.
Renewable resource energy sources which are
continuously replenished by natural processes:
wind, solar, biomass and geothermal.
Transmission grid the network of power lines
and associated equipment required to deliver
electricity from generating facilities to consumers.
Transmission constraints areas within the trans-
mission system where problems with delivering
electricity from generator to customer develop,
including power lines with too little capacity for
the amount of electricity to be moved.
Utility-scale (commercial-scale) a power gener-
ating facility designed to output enough electri-
city for purchase by a utility.
W (watt) instantaneous measure of power, equiv-
alent to just less than one thousandth of a horse
power and just over three thousandths of a BTU.
Watts per square meter of the blade swept area
unit used to measure wind power density.
Wind power measured in watts per square meter.
Wind speed measured in meters per second.
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