Environmental Engineering Reference
In-Depth Information
Candidate species:
Plants and animals for which the U.S. Fish and Wildlife Service
(FWS) has sufficient information on their biological status and threats to
propose them as endangered or threatened under the Endangered Species
Act (ESA), but for which development of a proposed listing regulation is
precluded by other higher priority listing activities.
Canopy:
The layer of foliage formed by the crowns of trees in a stand. For stands
with trees of different heights, foresters often distinguish among the upper,
middle, and lower canopy layers. These represent foliage on tall, medium,
and short trees. The uppermost layers are called the
overstory
.
Cap rocks:
Rocks of low permeability that overlie a geothermal reservoir.
Capacity factor:
The ratio of the electrical energy produced by a generating unit for
the period of time considered to the electrical energy that could have been
produced at continuous full-power operation during the same period.
Capacity, gross:
The full-load continuous rating of a generator, prime mover, or other
electric equipment under specified conditions as designated by the manufac-
turer. It is usually indicated on a nameplate attached to the equipment.
Capitol cost:
The cost of field development and plant construction and the equip-
ment required for the generation of electricity.
Carbon:
A nonmetallic element (symbol C) found in all organic substances and in
some inorganic substances such as coal and natural gas. The atomic weight
of C is 12, and that of CO
2
is 44. Emissions expressed in units of C can be
converted to emissions in CO
2
units by multiplying by 12/44.
Carbon accounting:
In general, refers to processes undertaken to measure amounts
of carbon dioxide equivalents emitted by an entity. It is used, for example,
by nation states, corporations, and individuals.
Carbon budget:
Balance of the exchanges (incomes and losses) of carbon between
carbon sinks (e.g., atmosphere, biosphere) in the carbon cycle.
Carbon cycle:
All carbon sinks and exchanges of carbon from one sink to another
by various chemical, physical, geological, and biological processes (refer to
Fig u re 9.1).
Carbon dioxide (CO
2
):
A product of combustion; the most common greenhouse
gas.
Carbon dioxide equivalent (CDE):
The amount of carbon dioxide by weight emit-
ted into the atmosphere that would produce the same estimated radiative
force as a given weight of another radiatively active gas. Carbon dioxide
equivalents are computed by multiplying the weight of the gas being mea-
sured (e.g., methane) by its estimated global warming potential (21 for
methane).
Carbon equivalent units
are defined as carbon dioxide equiva-
lents multiplied by the carbon content of carbon dioxide (i.e., 12/44).
Carbon intensity:
The amount of carbon by weight emitted per unit of energy con-
sumed. A common measure of carbon intensity is the weight of carbon per
British thermal unit (Btu) of energy. When there is only one fossil fuel under
consideration, the carbon intensity and the emissions coefficient are identi-
cal. When there are several fuels, carbon intensity is based on their com-
bined emissions coefficients weighted by their energy consumption levels.
