Energy correlates to human activity
Natural processes, through their evolution over millions of
years of time, are very energy-efficient. Artificial processes
are, in contrast, very inefficient. The most destructive processes
we undertake, for instance mining, electric generation and automotive
transportation all consume very large amounts of energy. The extent
to which artificial (and therefore environmentally damaging) processes
correlate to higher energy processes is often surprising and amazing.
Take for example, farming. The artificial chemicals that are used by
industrial farms in fact require larger amounts of energy to produce,
so that even an environmental issue as subtle as organic foods is reflected
in the products' energy content.
Energy provides a numeric scale for consumer and policy decisions
Since lifecycle energy analysis yields a single, numeric value that is a
rough equivalent to a given product's total environmental impact, one
can easily compare the relative environmental importance of unrelated
products and activities. For instance a decision to drive your car from
one location to another may have the same environmental impact as 1,000
choices between paper or plastic bags at the grocery store. Consumers
benefit from this information because it allows them to focus on the
important decisions, and stop worrying about the unimportant ones.
Advocates and policymakers also benefit in the same way, by knowing
which issues are worth substantial attention, and which not.
Energy is the ultimate limit to a sustainable economy
Every day, the earth receives a great deal of energy from the sun.
This energy is "free" to us; it comes with no environmental costs.
It is also the only source of energy that is, for all practical purposes,
infinite in supply. As we look forward to creating a sustainable economy
for the planet, a project that will take hundreds of years to complete, it
becomes clear that the sun is the only source of energy we can rely on
indefinitely. The amount of energy we receive from the sun each day is
very well known, so it is extremely important to understand how much
economic activity the environment can support on an energy basis.
Fortunately, we can reap solar energy in many ways. Photovoltaic
cells and solar thermal plants both recover solar energy directly.
But solar energy also powers the natural processes that create wind,
running water and biomass, all of which can be used to generate
electric and heat energy as well.
Energy content is a window into climate change
Probably the single greatest threat to our environment at this moment
is global climate change. A primary contributor to this problem is
carbon dioxide, a by-product of combustion-based energy generation.
By cataloguing the type of energy involved in each phase of a product,
we can also measure that product's contribution to climate change,
a subject of immediate importance.
Balance equations are possible
Energy is the most fundamental quantity recognized in the science
of physics. Especially important, energy is a "conserved" quantity:
it cannot be destroyed or created. This means that calculations
ILEA makes regarding energy use in natural and human-influenced
ecosystems can be checked for accuracy using energy balance
equations: the energy input into a system must be exactly
equal to the energy output.
One special application of energy balance equations is the
calculation of the Earth's maximum sustainable carrying capacity.
This is the maximum number of human beings the planet can carry
while maintaining a functional ecosystem running on solar energy
alone (since this is the only source of energy that will last
indefinitely). Preliminary estimates of the carrying capacity
are approximately 2 billion people; the current world population
is already three times this number! More precise calculations of
the carrying capacity are necessary, and measures of the total
energy impact of various lifestyles are fundamental inputs to this calculation.
Last Modified on Sept. 12, 2003.