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.

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