Chapter IV, Section C: The Environmental Energy Debits
If solar energy and water are the energy assets of an ecosystem,
what are the debits? What are the greatest environmental threats in
terms of the energy demands to address them? In short, the main
energy debits, broadly, are related to 1) air, water, and soil
contamination, 2) acid precipitation and acid mine drainage, 3)
eutrophication leading to a “dissolved oxygen crisis” for aquatic
biota and 4) reduction in biodiversity, caused by all of the above
as well as habitat destruction, particularly, but certainly not
exclusively, rainforest destruction. Notably, this list does not
include the climate change problem. The energy required to remove
greenhouse gases from the environment is a large, but yet unknown,
percentage of our total energy consumption, of which 85% is
currently tapped from fossil fuels. The greenhouse gasses represent
carbon and other compounds at their highest entropy state, thus
represent the entropy already accumulated by human history. Though
research in carbon sequestration is ongoing, including into carbon
sinks such as carbon solids, plant uptake, and increasing ocean
uptake, and into storage in subsurface reservoirs, all of the
processes require energy to essentially concentrate carbon from a
free, liberated gas state. The ultimate carbon sink in the natural
carbon cycle, at least the one that spans geologic orders of time,
is onto the seafloor by carbonate sedimentation, the carbonate
itself produced by biota, which ultimately uses solar energy to make
shells. Another notable exception to the energy debit list above is
upper atmospheric ozone depletion, though this is broadly a
contaminant related issue. What is important to realize is that the
boundaries of these energy debit assessments do not correspond
necessarily to the media of occurrence of the environmental problem,
hence the ability of problems and their solutions to shift energy
debits into other systems.
Environmental issues are usually discussed, and even addressed
wholly in terms of the media of their occurrence, that is, whether
the issue is one of land, air, or water “pollution.” The boundaries
between these media are not barriers, and often become a source of
feedback when an environmental problem simply exchanges media. The
problem with media-specific conceptualization of environmental
issues is that often, the proposed solution for one media may lead
to an environmental liability in another. The most salient, recent
example of this is the addition of MTBE to gasoline to reduce
tailpipe emissions, an air pollution problem. Unfortunately in turn,
MTBE became a source of persistent ground water contamination
associated with very-commonly-occurring fuel tank leaks of petroleum
hydrocarbons. These hydrocarbons normally biodegrade relatively
quickly, thus limiting the spread of the contamination, but MTBE
plumes became relatively extensive. Thus an air pollution problem
was exchanged for an increased groundwater pollution problem. Though
the following discussion may be in the context of a typical media,
particularly when discussing examples, the following classification
should be considered media independent, and usually apply to all
media.