Cork has a unique cell structure and organic
characteristic that makes it soft to walk on; it
repels dust, bugs, and mildew, and is a good
thermal and sound insulator. Because of its high
fire-resistance qualities, cork is used in rocket
technology. In buildings, cork can be used for
its antivibrational, thermal, and acoustic absorbing
properties. It can also be used for seals and
gaskets, in expansion joints, and for intumescent
strips. It has even been used for building exteriors.
Granules of cork can also be mixed into concrete.
The composites made by mixing cork granules
and cement have low thermal conductivity, low
density, and good energy absorption. See also:
Bamboo
Corn Also known as maize. An energy crop
used to produce biofuel, mostly ethanol. Etha-
nol produced from cellulosic materials produces
fewer pollutant emissions than fossil fuels when
combusted. Decreased emissions of greenhouse
gases such as CO
2
is a benefit of ethanol.
Researchers have found that extensive cultivation
of corn for use as a biofuel would have a negative
impact on water because of its higher nitrogen
fertilization rate and greater nitrogen runoff. A
higher nitrogen content in water would result in
hypoxic zones and possible eutrophication of
rivers, lakes, and streams.
The diversion of corn as a food crop to an
ingredient for biofuel may contribute to a shortage
of food worldwide. Researchers have suggested
other crops, such as rapeseed and soybeans,
and cellulosic fibrous plants such as switchgrass
and willow trees, as alternative ingredients for
biofuel.
Corporate Average Fuel Economy (CAFE) US
automobile fuel efficiency standard, established
by Congress in 1975 as the sales-weighted
average fuel economy expressed in miles per
gallon (MPG) of a manufacturer’s fleet of pas-
senger cars or light trucks with a gross vehicle
weight rating (GVWR) of 8500 pounds or less,
manufactured for sale in the USA. CAFE was
originally intended to improve the average fuel
economy of cars and light trucks (trucks, vans,
and sport utility vehicles) sold in the USA in the
wake of the 1973 Arab oil embargo. The goal
was to double new car fuel economy by 1985.
The USA has the lowest standard of fuel
economy of any nation in the world, including
China; the European Union and Japan have fuel
economy standards almost twice as high as the
USA. US Congress specifies that CAFE standards
must be set at the “maximum feasible level”,which
includes: i) technological feasibility; ii) economic
practicability; iii) effect of other standards on fuel
economy; iv) need of the nation to conserve
energy. See also:
Fuel economy, automobile; Fuel
economy regulations, automobile
Corrective action See: Cleanup
COTE See: Committee on the Environment
Cover crops Crops planted immediately after
harvest to prevent soil erosion. Common cover
crops are rye, clover, and alfalfa.
CPS See:
Concentrating solar power system
Cradle to cradle Process of rethinking the way
people live, work, travel, design, build, and
consume so that production not only is efficient,
but also minimizes waste. A phrase invented by
Walter R. Stahel in the 1970s and popularized
by William McDonough and Michael Braungart
in their 2002 book of the same name. In cradle
to cradle production, all material inputs and out-
puts are seen as either technical or biological
nutrients. Technical nutrients can be recycled or
reused with no loss of quality; biological nutri-
ents can be composted or consumed. By con-
trast, cradle to grave refers to a company taking
responsibility for the disposal of goods it has
produced, but not necessarily putting products’
constituent components back into service.
Cradle to cradle 63