III. c. 2. The Agricultural Biofuels Fallacy
The biggest and, quite frankly, most dangerous environmental fallacy
of all time is the fallacy that the production of agricultural
biofuel can ever balance as a net energy positive. The reasons are
best articulated by Richard Manning in The Oil We
Eat, and are highlighted here. And yet this fallacy is
championed by ardent “environmentalists” almost as a political
litmus test of “green consciousness.” Unfortunately, articles in no
less prestigious journals as Science have concluded that
agricultural biofuels can produce more energy output than the inputs
to farming and fertilizing, but these analyses completely disregard
the damage to the environment that renders the practice
unsustainable. Unfortunately, the fallacy is championed at the top
from none other than our Nobel Prize winning Energy Secretary,
Steven Chu, who has promoted an idea that glucose can be grown in
the tropics and shipped globally as fuel. It underscores that a
brilliant physicist can be an idiot when it comes to the
environment. The idea that tropical “agriculture” could sustainably
produce a net energy output neglects the fundamental facts that,
unlike the soils of temperate forests, tropical laterite soils are
infertile, better used for iron and aluminum ore, that essentially
all of the biomass and nutrient cycling occurs above grade, and that
the intricate tropical ecosystems would never support the
monoculture needed to produce biofuel.
To be clear, agricultural biofuel is not the same as waste-stream
biofuel. The news is full of stories about innovative and
enterprising auto enthusiasts using biodiesel produced from offal or
restaurant grease to run their car or truck. Few would argue against
producing a biofuel that neutralizes waste and results in a net
energy output from a waste stream that already exists. Other systems
exist for producing hydrogen, ethanol, methane, and biodiesel, to
name but a few fuels that can be produced from various wastes. But
that is not the subject at hand. The potential energy output from
waste streams is not enough to justify the hype over biofuels. Thus
the common term “biofuel” is mostly synonymous with the term
“agricultural biofuel.”
Agricultural biofuel is produced from an agricultural product,
usually a high-energy seed, and not from an agricultural waste or
by-product. As Manning shows, a tremendous amount of environmental
damage is already attributable to the high-energy seeds we grow for
food, which unlike transportation, is a non-optional sustainability
need. But the knowledge of this environmental damage should clearly
admonish the concept of agricultural biofuel. The reaction of the
agricultural biofuel community to these criticisms is to hang their
hat on cellulosic biofuel, with the goal to ultimately use vast
stretches of agricultural “wasteland” for growing switch grass.
These “wastelands” are habitats promoting biodiversity. Even though
the grass can be native to the habitat, when harvested, the grass
becomes just another monoculture, with all of the associated impacts
on the biosphere as a whole, and soils in particular, all grown for
an extremely meager biological conversion of solar energy.
The most significant contribution to human knowledge from the field
of ecology is the understanding of the movement of energy through
the trophic (feeding) levels of the food web, and the concomitant
nutrient cycles that accommodate the growth of life. The early
ecologists tracking energy through ecosystems, scientists such as Charles
Elton and Raymond
Lindeman, discovered that most primary producing plants, the
autotrophs forming the root of a food web, could only convert about
one tenth of one percent of the available incoming solar radiation
into the energy stored in biomass, part of which is ultimately made
available to the heterotrophs of the first trophic level. For
comparison, this solar conversion efficiency of a meager 0.1% is
dwarfed by the solar efficiency of even cheap photovoltaic cells,
most ranging from 10% to 15%, with higher end concentrated
photovoltaics reaching upwards of 40%. Unfortunately we cannot eat
from photovoltage, an electrical potential energy, rather we require
chemical potential energy in the form of food. As a result, the
largest percentage of human habitable real estate is devoted to
agriculture, land that if it were to remain solely for human
utilization, could otherwise be devoted to solar power generation.
After the low rate of energy return from solar energy to plant food,
only 10% of
the herbivore’s energy consumed at the first trophic level is
available as biomass to the carnivore at the second level, a rate of
return that is repeated for each trophic level up the food web. This
is the vegetarian’s argument for eating at the lowest trophic level,
and is also the reason that even a meat eater’s diet, except for
fish, is rarely derived from a trophic level higher than the second
level.
Agriculture’s huge energy consumption only begins with the
inefficient solar conversion. Food also requires nutrients, and the
nutrient cycles themselves require the transformation of energy with
even more losses by the second law. “What everyone knows” is that
the oil from the Middle East is central to our transportation
system, and with a little extended thought, realizes that it is
central to our industry and agriculture. What far fewer realize is
that the oil energy itself is incorporated into our food energy in
the form of fixed nitrogen. Thus in addition to the energy
equivalent of 4,000 Nagasaki bombs consumed just to turn the soil
every year in Iowa alone, Manning outlined in detail our dependence
on oil for the nutrients food requires. Fixed nitrogen is provided
to our agriculture in the form of ammonia fertilizer, produced not
only using energy, but hydrogen derived from an energy resource
itself--natural gas--as an ingredient. Currently 1% of energy
consumption in the world goes into the production of ammonia, with
at least 40% of the world’s population dependent on this production
for food.
The energy arguments against agricultural biofuel do not even begin
to include the environmental arguments against it, particularly the
environmental ramifications of ammonia fertilizer use. Ammonia
readily converts to nitrate in the soil, and it is the nitrate that
is taken up by plants. Nitrate application in all its forms has an
enormous impact on the environment. Nitrate and phosphorus,
providing essential elements to make proteins, are limiting
nutrients in the environment. A little is a good thing; a lot is
detrimental, creating a condition of excess nutrients in an
ecosystem referred to as eutrophication. When used in excess,
nitrate runoff into waterways proliferates plant and algal life in
aquatic ecosystems, which in turn consumes the dissolved oxygen in
the water from plant respiration and decay, a condition referred to
as hypoxia. Hypoxia kills aquatic animal life, resulting in even
more decay and a reduction in biodiversity. The degradation of
waterways does not stop at local rivers or lakes, it extends to the
ocean. Manning’s article describes a dead zone in the Gulf of Mexico
due to the Mississippi River’s return flow of nitrate from the U.S.
farm belt. Thus in the end, the order produced in our bodily
systems, produced by the energy in our food, ultimately results in
the disorder of a marine aquatic ecosystem.
Manning’s article, addressing both the energy demands and
environmental ramifications of agriculture, should be mandatory
reading for all of Earth’s inhabitants, including Nobel Prize
winning Energy Secretaries. The thought of using petroleum
fertilizer to grow seeds or grass, with a 0.1% solar conversion
efficiency to make a carbon based fuel, whether it’s ethanol or
glucose, to replace petroleum is ludicrous. Luckily dumb ideas die
quickly thermodynamically, economically dying if for no other reason
the increased cost of the ethanol in beer. The worldwide awareness
that oil and its derivatives are central to our very survival--our
food--will lead to demands that the use of petroleum be rather
prioritized toward the human right for food.