Environmental Engineering Reference
In-Depth Information
The “carbon footprint,” which is often used as shorthand for the amount of car-
bon being emitted by an activity or organization, is an important contributor to the
ecological footprint. The carbon component of the Ecological Footprint translates
to the amount of productive land and sea area required to sequester carbon dioxide
emissions. This is an indicator of the demand the burning of fossil fuels places on
the planet.
There are several approaches to converting fossil fuel energy consumption into
a corresponding land area. Each is based on a different rationale, but all produce
approximately the same results: the annual per capita world consumption of 2 tons
of oil equivalent (80 EJ) corresponds to the use of one hectare of ecologically pro-
ductive land. One hectare is the size of a soccer field (or 10,000 m
2
).
Ethanol is a potentially renewable energy carrier that is technically and qualitat-
ively equivalent to a fossil fuel. It is a homogeneous, concentrated fuel that can be
stored and transported easily and can power human processes the same way fossil
hydrocarbons do. For these reasons it is already being used in some places as a sup-
plement to gasoline. The land area corresponding to fossil fuel consumption can
therefore be represented as the productive land necessary to produce the equival-
ent amount of ethanol. This area comprises the amount of land needed to grow the
plant material, usually sugarcane or corn, and the processing energy necessary to
produce them.
Another method estimates the land area needed to sequester the CO
2
emitted
from burning fossil fuel. The argument for this approach is that fossil carbon (in
the form of CO
2
) cannot be allowed to accumulate in the atmosphere if we wish to
avoid possible climate change. If we continue to consume excessive quantities of
fossil fuel, we have a responsibility to manage the waste products. This approach
requires that we calculate the amount of “carbon sink” land require to assimilate
the fossil CO
2
that we are injecting into the atmosphere.
Other contributions to the ecological footprint come from cropland, grazing
land, fishing grounds, forest land, and built-up land.
According to the various ecological footprint calculations, humanity has already
surpassed the capacity of the Earth to produce the resources needed and absorb the
wastes it generates. The way to reverse this grim situation is to reduce dramatically
fossil fuel consumption and adopt sustainable practices in other societal activities.
