Environmental Engineering Reference
In-Depth Information
Municipal waste:
Defined in the Energy Security Act (P.L. 96-294; 1960) as “any
organic matter, including sewage, sewage sludge, and industrial or commer-
cial waste, and mixtures of such matter and inorganic refuse from any pub-
licly or privately operated municipal waste collection or similar disposal
system, or from similar waste flows (other than such flows which constitute
agricultural wastes or residues, or wood wastes or residues from wood har-
vesting activities or production of forest products).”
N
Nacelle (or cowling):
Contains and protects the gearbox and generator; sometimes
it is large enough for an engineer or technician to stand in while doing
maintenance.
Naphtha:
Generic term applied to a petroleum fraction with an approximate boiling
range between 122 and 400°F.
Native:
A species that, other than as a result of an introduction, historically occurred
or currently occurs in a particular ecosystem.
Native gas:
A gaseous mixture of hydrocarbon compounds, the primary one being
methane.
Native plant:
A plant that has grown in the region since the last glaciation and
occurred before European settlement.
Natural gas:
A gaseous mixture of hydrocarbon compounds, the primary one being
methane.
Natural processes:
A complex mix of interactions among animals, plants, and their
environment that ensures maintenance of an ecosystem's full range of bio-
diversity. Examples include population and predator-prey dynamics, pol-
lination and seed dispersal, nutrient cycling, migration, and dispersal.
Natural sinks:
In reference to greenhouse gases, any natural process in which these
gases are absorbed from the atmosphere.
Near tree:
Trees located within approximately 15 m (50 ft) of a building so as to
directly influence irradiance and air flow on the building envelope.
Net head:
The gross head minus all hydraulic losses except those chargeable to the
turbine.
Net metering:
Arrangement that permits a facility (using a meter that reads inflows
and outflows of electricity) to sell any excess power it generates over its load
requirement back to the electrical grid to offset consumption.
Net photovoltaic cell shipment:
The difference between photovoltaic cell ship-
ments and photovoltaic cell purchases.
Net photovoltaic module shipment:
The difference between photovoltaic module
shipments and photovoltaic module purchases.
Net summer capacity:
The maximum output, commonly expressed in megawatts
(MW), that generating equipment can supply to system load, as demon-
strated by a multiple-hour test at the time of summer peak demand. This
output reflects a reduction in capacity due to electricity used for station
service or auxiliaries.
Niche:
The specific part or smallest unit of a habitat occupied by an organism.
