Environmental Engineering Reference
In-Depth Information
Glossary
*
A
Absorber:
In a photovoltaic device, the material that readily absorbs photons to
generate charge carriers (free electrons or holes).
AC:
Alternating current.
Acid hydrolysis:
A chemical process in which acid is used to convert cellulose or
starch to sugar.
Acid mine drainage:
A cause of water pollution that results when sulfur-bearing
minerals associated with coal are exposed to air and water and form sul-
furic acid and ferrous sulfate. The ferrous sulfate can further react to form
ferric hydroxide, or yellow boy, a yellow-orange iron precipitate found in
streams and rivers polluted by acid mine drainage.
Acid rain:
Also called
acid precipitation
or
acid deposition
, acid rain is precipita-
tion containing harmful amounts of nitric and sulfuric acids formed pri-
marily by sulfur dioxide and nitrogen oxides released into the atmosphere
when fossil fuels are burned. It can be wet precipitation (rain, snow, or
fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol
particles, or dust). Acid rain has a pH below 5.6. Normal rain has a pH of
about 5.6, which is slightly acidic. The term pH is a measure of acidity or
alkalinity and ranges from 0 to 14. A pH measurement of 7 is regarded as
neutral. Measurements below 7 indicate increased acidity, and those above
7 indicate increased alkalinity.
Acre-foot:
The volume of water that will cover an area of 1 acre to a depth of 1 foot.
Acreage:
An area, measured in acres, that is subject to ownership or control by those
holding total or fractional shares of working interests. Acreage is consid-
ered developed when development has been completed. A distinction may
be made between gross acreage and net acreage:
Gross
—All acreage covered by any working interest, regardless of the per-
centage of ownership in the interest.
Net
—Gross acreage adjusted to reflect the percentage of ownership in the
working interest in the acreage.
Active power:
The component of electric power that performs work, typically mea-
sured in kilowatts (kW) or megawatts (MW). Also known as
real power
.
The terms “active” or “real” are used to modify the base term “power” to
differentiate it from reactive power.
*
Some definitions are adapted from EERE,
Glossary of Energy-Related Terms
, Office of Energy
Efficiency & Renewable Energy, Washington, DC, 2014 (
http
:
//energy.gov/eere/energybasics/articles/
glossary-energy-related-terms);
EIA,
Glossary
, U.S. Energy Information Administration, Washington,
DC, 2014 (http://www.eia.gov/tools/glossary/index.cfm?id=A).
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