Glossary
Air foil-another term for the blades of
the wind generating system.
Anemometer- a device used to measure the velocity of wind
at a site.
Availability factor- the amount of time (in percentages) that
a wind generator can operate. Availability is lost due to routine
repairs and maintenance. Modern generators typically sport 98%
availability.
Avoided cost - the rate which Michigan utilities, unless negotiated
otherwise, will pay for renewable energy; currently about 1.8
cents/kWh. Calculated on the variable costs of producing coal-fired
electricity.
Capacity factor- the amount of power generated
by a windmill divided by its maximum output. Most installations
operate at about 25 to 40% of full capacity, primarily because
of wind variability.
Cogeneration -- A process that combines the generation
of electricity with a separate use of the thermal energy created.
For instance, a paper factory might generate its own electricity
and use the surplus heat to dry its paper.
Controller-starts the wind generator when there is sufficient
wind and stops it when wind speeds rise to speeds at which damage
to the unit could occur.
Cooperative -- A form of utility in which all users own
shares. Cooperatives are common in rural areas that are expensive
to serve because of the long distances between users. Frequently,
the government contributes in various ways to rural cooperatives
to reduce costs to individual owner/users.
Cost-of-service ratemaking -- A system for establishing
prices in which a utility is reimbursed for the legitimate costs
it encounters in serving customers plus a specific percentage
for profit.
Cut-in speed- the wind speed at which a windmill's rotors
begin to turn. Commonly about 10 miles per hour.
Cut-out speed-the wind speed at which damage to the unit
might occur. Units are engineered to stop the rotors at this speed
of wind, usually about 55 to 65 miles per hour.
Demand-Side management (DSM) -- The process
of managing the consumption of energy. DSM programs include, for
instance, offering discounts on new, high-efficiency appliances
so that consumers get rid of their older, less efficient models.
Deregulation -- The process of removing restrictive regulations
on previously regulated companies.
Distributed Generation -- A small-scale power-generation
technology that provides electric power at a site closer to customers
than central station generation. The term is commonly used to
indicate non-utility sources of electricity, including facilities
for self-generation.
Down-wind turbine-a wind generator (usually two-bladed)
where the blades are in back of the nacelle, facing away from
the wind. See "up-wind turbine" for comparison.
Energy Policy Act of 1992 (EPAct)
-- A federal statute that, among other things, established additional
forms of non-utility generators. It also permitted non-generator-owning
municipalities to purchase wholesale electricity, thus opening
the door to municipalization.
Environmental Impact Statement -- A thorough study of each
proposed electric utility project with potential for significant
environmental impacts, including evaluation of alternatives and
mitigation.
Environmental Quality Board State agency that adopts environmental
rules, monitors their effectiveness and revises as appropriate;
provides technical assistance to interpret and apply rules.
Federal Energy Regulatory Commission
(FERC) -- An independent regulatory agency within the U.S.
Department of Energy that has jurisdiction over interstate electricity
sales, wholesale electricity rates, natural gas and oil pipeline
rates, and gas pipeline certification. It also licenses and inspects
private, municipal, and state hydroelectric projects and oversees
related environmental matters.
Fuel cell -- A battery-like piece of equipment used to
generate electricity on a small scale. Unlike a battery, it does
not run down because it is constantly refueled by, for instance,
natural gas.
Gear box-located in the nacelle,
the gear box steps up the speed of the rotation from a low speed
shaft connected to the blades to a high speed shaft connected
to the generator.
Generation -- The conversion of other forms of energy into
electricity through the use of equipment. Generation is measured
in kilowatt-hours.
Green energy -- A popular term for energy produced from
renewable energy resources or, sometimes, from clean (low-emitting)
energy sources.
Green marketing -- Selling green energy.
Grid -- A network of power lines or pipelines used to move
energy.
High speed shaft-connects the gear
box to the generator.
Independent power producer (IPP)
-- An electricity generator that sells power to others but is
not owned by a utility.
Independent systems operator (ISO) -- An impartial, independent
third party responsible for maintaining secure and economic operation
of an open access transmission system on a regional basis. It
provides availability and transmission pricing services to all
users of the transmission grid.
Investor-owned utility (IOU) -- A utility with stock-based
ownership.
KWh/MWh Kilowatt hours and
megawatt hours. Power is measured in watts. Energy is measured
in watt hours. A watt hour is 1 watt of power applied for 1 hour.
A KWh is one thousand watt hours. A MWh is one million watt hours.
Scientists use joules to express energy, but KWh are more familiar
and more useful here. (1 KWh = 3.6 million joules or 3.6 MJ)
Low-speed shaft-connects the blades
to the gear box.
Municipal utility or Muni-- A utility
owned by a city. Generally, surpluses in revenues over expenditures
are contributed to the city budget.
MWh/KWh Megawatt hours and kilowatt hours. Power
is measured in watts. Energy is measured in watt hours. A watt
hour is 1 watt of power applied for 1 hour. A KWh is one thousand
watt hours. A MWh is one million watt hours. Scientists use joules
to express energy, but KWh are more familiar and more useful here.
(1 KWh = 3.6 million joules or 3.6 MJ)
Nacelle - the structure at the top
of the wind tower where key components such as the rotor shaft,
gearbox, and generator are installed.
Net Metering - Primarily for small wind and other small
renewable energy producers, allows producers to receive credit
for putting excess power onto the grid. Net metering is most beneficial
when credited annually, so wind energy produced in the winter
can offset higher summer electric bills. Michigan's Public Service
Commission is working on a net metering consensus in 2005.
NREL-National Renewable Energy Research Laboratory. A US
Department of Energy research facility.
Production Tax Credit (PTC) -- Provides
the owner of a qualifying facility with an annual tax credit based
on the amount of electricity that is generated. By focusing on
the energy produced instead of capital invested, this type of
tax incentive encourages projects that perform adequately.
Public Utility Regulatory Policies Act (PURPA) -- A 1978
federal law that requires electric utilities to purchase electricity
produced from certain efficient power producers (frequently using
renewable energy or natural gas). Utilities purchase power at
a rate equal to the costs they avoid by not generating the power
themselves. State regulatory agencies establish the rate based
on local conditions.
Public Services Commission (PSC) -- A state government
agency responsible for the regulation of public utilities within
a state or region. A state legislature oversees the PSC by reviewing
changes to utility laws, rules and regulations and approving the
PUC's budget. Michigan has three Commissioners appointed by the
governor with advice or consent of the Senate. The PUC focuses
on adequate, safe, universal utility service at reasonable rates
while also trying to balance the interests of consumers, environmentalists,
utilities, and stockholders.
Rated wind speed- the wind speed
at which a wind generator produces the amount of power at which
the unit is rated.
Renewable energy -- Energy derived from resources that
are regenerative or for all practical purposes cannot be depleted.
Types of renewable energy resources include moving water (hydro,
tidal, and wave power), thermal gradients in ocean water, biomass,
geothermal energy, solar energy, and wind energy. Municipal solid
waste (MSW) is also considered by many to be a renewable energy
resource.
Renewables portfolio standard (RPS) -- A (proposed) minimum
renewable energy requirement for a region's electricity mix. Under
an RPS, every electricity supplier would be required to provide
some percentage of its supply from renewable energy sources. RPS
proposals frequently ease that requirement by including a tradeable
credit system under which electricity suppliers can meet the requirement
by buying and selling renewable generation credits. Michigan currently
does not have an RPS. About 20 other states do have an RPS.
Restructuring -- The process of changing the structure
of the electric power industry from one of guaranteed monopoly
over service territories to one of open competition between power
suppliers for customers.
Rotor-the part of the nacelle that spins as the blades
turn in the wind.
Rural Electrification Administration (REA) -- An agency
of the U.S. Dept. of Agriculture that makes loans to states and
territories in the U.S. for rural electrification and for providing
electricity to persons in rural areas who do not receive central
station service. It also furnishes and improves electric and telephone
service in rural areas, fosters energy conservation and on-grid
and off-grid renewable energy systems, and studies the condition
and progress of rural electrification.
Shear --
A change of wind speed and direction associated with different altitudes and
physical characteristics of the surrounding landscape.
System benefits charge (SBC) --
A required fee (also known as a public benefits charge) from all
electricity customers to fund programs aimed at the public good
that may no longer be feasible for the utility to provide in a
competitive electricity market. These programs include energy
conservation, support for renewable energy use, low-income assistance,
and research and development.
Turbine -- A device for converting
the flow of a fluid (air, steam, water, or hot gases) into mechanical
motion that in turn produces electricity.
Transformer-a device used to regulate the electricity coming
from the generator.
Unbundling -- The process of separating
a service into component parts and permitting customers to buy
each separately. Utility unbundling, overseen by regulators, generally
requires utilities to ensure that the price of each service accurately
reflects the cost of that service (plus a margin for profit).
In this way, unbundling helps ensure that customers pay for what
they receive and are not forced to subsidize services they do
not use.
Utility-scale wind-units typically used by power companies
to produce large amounts of electricity, typically.
Up-wind turbine-a wind generator with the blades in front
of the nacelle, facing the wind. This is the most common configuration
for wind generators. See down-wind turbine for comparison.
Wind power class- a rating system
to designate regions by their potential for wind power generation,
with class 1 being the lowest potential and class 7 being the
highest potential.
Yaw drive-turns the nacelle to face
the wind as wind direction changes. Down-wind turbines don't require
yaw drives as the wind blows the rotor downwind through natural
forces.
Sources: Windustry/American Wind Energy Association, University
of North Dakota, Massachusetts Technology Collaborative, National
Renewable Energy Laboratory.
