THERMODYNAMICS AND THE SUSTAINABILITY OF FOOD PRODUCTION
by Jay Hanson -- revised 11/19/96
"Erwin Schrodinger (1945) has described life as a system in
steady-state thermodynamic disequilibrium that maintains its
constant distance from equilibrium (death) by feeding on low
entropy from its environment -- that is, by exchanging high-
entropy outputs for low-entropy inputs. The same statement
would hold verbatium as a physical description of our
economic process. A corollary of this statement is that an
organism cannot live in a medium of its own waste products."
-- Daly and Townsend
. . .
All matter and energy in the universe are subject to the Laws
of Thermodynamics. In the discipline of Ecological Economics,
systems are delimited so that they are meaningful to our economy.
What does thermodynamics have to do with the sustainability of
The two essential forms of stored thermodynamic potential
are "energy" (e.g., a barrel of oil) and "order" (e.g., clean
drinking water and deep topsoil). "Entropy" is a measure of the
unavailability of energy: the entropy of oil increases as it
burns, and the entropy of a water table increases as it falls
because more energy will be required to pump it to the surface.
Entropy can also be thought of as a measure of disorder in
a system: polluted water that requires purification has higher
entropy than the same water unpolluted, and the entropy of
topsoil increases when it erodes or is polluted by salt from
evaporating irrigation water.
Sustainable systems are "circular" (outputs become inputs)
-- all linear physical systems must eventually end. Modern
agriculture is increasing entropy in both its sources (e.g.,
energy, soil, and ground water) and its sinks (e.g., water and
soil). Thus, modern agriculture is not circular -- it can not
Consider the most important limiting variable -- energy.
There is NO substitute for energy. Although the economy
treats energy just like any other resource, it is NOT like
any other resource. Energy is the precondition for ALL other
resources and oil is the most important form of energy we
use, making up about 38 percent of the world energy supply.
NO other energy source equals oil's intrinsic qualities of
extractablility, transpotability, versatility and cost. These
are the qualities that enabled oil to take over from coal as
the front-line energy source in the industrialized world in the
middle of this century, and they are as relevant today as they
40 years ago, geologist M. King Hubbert developed a method
for projecting future oil production and predicted that oil
production in the lower-48 states would peak about 1970. These
predictions have proved to be remarkably accurate. Both total
and peak yields have risen slightly compared to Hubbert's
original estimate, but the timing of the peak and the general
downward trend of production were correct.
In March of this year, World Resources Institute published
a report that stated:
"Two important conclusions emerge from this discussion.
First, if growth in world demand continues at a modest 2
percent per year, production could begin declining as soon
as the year 2000. Second, even enormous (and unlikely)
increases in [estimated ultimately recoverable] oil buy the
world little more than another decade (from 2007 to 2018).
In short, unless growth in world oil demand is sharply lower
than generally projected, world oil production will probably
begin its long-term decline soon -- and certainly within the
next two decades."
Well, so much for oil! Should we be alarmed? YES! Modern
agriculture -- indeed, all of modern civilization -- requires
massive, uninterrupted flows of oil-based energy. For example,
the International Energy Agency projects that world oil demand
will rise from the current 68 million barrels per day to around
76 million b/d in year 2000 and 94 million b/d in 2010. What
will happen when demand for oil exceeds maximum possible
To really understand the underlying causes and implications
of oil depletion, one must stop thinking of the "dollar cost" of
oil, and take a look at the "energy cost" of oil. We note that
the energy cost of domestic oil has risen dramatically since
1975. As oil becomes harder and harder to find and get out
of the ground, more and more energy is required to recover each
barrel. In other words, the increasing energy cost of energy is
due to increasing entropy (disorder) in our biosphere.
Optimists tend to assume that the "type" of energy we use
is not significant (e.g., liquid vs. solid), that an infinite
amount of social capital is available to search for and produce
energy, and that an infinite flow of solar energy is available
for human use. Realists know that none of these assumptions is
In fact, all alternative methods of energy production
require oil-based energy inputs and are subject to the same
inevitable increases in entropy. Thus, there is NO solution to
the energy (entropy or disorder) problem, and the worldwide
energy-food crisis is inevitable.
When we can no longer subsidize modern agriculture with
massive fossil energy inputs (oil-based pesticides and
fertilizers, machine fuel, packaging, distribution, etc.), yields
will drop to what they were before the Green Revolution!
Moreover, billions of people could die this coming century when
the U.S. is no longer able to export food and mass starvation
sweeps the Earth.
Is there nothing we can do?
We could lessen human suffering if all the people of Earth
cooperated for the common good. But as long as political systems
serve only as corporate errand boys, we're dead.
1. p.p. 42-43, ENERGY AND THE ECOLOGICAL ECONOMICS OF SUSTAINABILITY,
John Peet; Island Press, 1992. ISBN 1-55963-160-0.
Phone: 800-828-1302 or 707-983-6432; FAX: 707-983-6164
3. p. 55, BEYOND OIL, Gever et al.; Univ. Press Colorado, 1991.
303-530-5337 See also:
7. p. 27, Gever et al., 1991.
8. Estimated in 1994 to be about 2025 by Pimentel. See:
Many entropy references are archived at: