Bio-diversity and Bio-fuels

It is remarkable that the debate over alternative, green energy resources has come so far. Ten years ago, corn ethanol was hardly known outside the world of futurist farmers and the halls of academia. Now, President Bush has voiced support for ethanol in the State of the Union address, challenging the nascent biofuels industry to produce 35 billion gallons of ethanol by 2015. Energy technology is at the forefront of our national debate.

The American public should be wary, however, of snake-oil salesman and golden-tongued charmers promoting one particular energy solution. A healthy dose of cynicism is valuable when assessing any elected leaders’ claim or plan, no less so for the President’s ambitious agenda. For all the talk of energy independence and reduced reliance on Middle Eastern oil, the motivation for corn ethanol is not sustainability and national security but politics and entrenched financial interests.

The agriculture lobby is well known throughout the U.S. as an effective and powerful figure in crafting, lobbying, and supporting the national Farm Bill, the work of laws and statutes that doles out millions of tax-payer dollars to farms. The majority of tax breaks and giveaways (including paradoxical payments to owners for keeping land out of production) go to enormous, high-technology, low-labor farms. The agri-business lobby is salivating over the growth of the corn ethanol movement, as President Bush’s State of the Union address has already resulted in an increase in the price of corn from $3.70 to $4.40 per bushel (a jump of almost 20%).

In terms of energy, corn ethanol is a seemingly logical place to start, with an immensely developed infrastructure and a forceful lobby that controls national policy. And for corn, the yields are huge: in one hectare of land (ha, about 2 football fields) over 90 gigajoules of energy can be produced (a single match contains about 1 joule of energy, and there are a trillion joules in one gigajoule [GJ]).

The energy output of corn ethanol dwarfs all other biofuels. So, too, the inputs required to grow corn are astronomical – the energy expended through farm equipment, fertilizers, herbicides and pesticides, and fuels needed to produce that hectare of corn almost matches the output derived from farming. On balance, corn ethanol has a large return only with an equally large investment. As a part of our national energy budget, we may as well not grow the corn in the first place, thereby saving on farm inputs what we would be attempting to produce as outputs.

But the striking inefficiencies of corn ethanol should not discourage us from all biofuels, lest we throw the baby out with the bath-water. A recent article in the journal Science by David Tilman, Jason Hill, and Clarence Lehman shows the potential for sustainable biofuels.

There is considerable nuance associated with the science and sustainability of biofuels, and a careful look at the details paints a fascinating portrait of an emerging and promising technologic venture. At left is a figure from the Tilman et al. article. On the vertical axis we see energy units (in GJ per ha), and along the horizontal axis are 5 potential biofuels: corn ethanol, soy diesel, and generic biomass electricity, ethanol, and synfuel. Each biofuel has two columns: the energy outputs (yield) and inputs. Below the x-axis are two calculations of the graphical data, Net Energy Balance (NEB = Output – Input) and the NEB ratio (NEB ratio = Output / Input), for each biofuel.

Unsurprisingly, corn ethanol dominates the field (pun intended) for both outputs and inputs. More importantly, the NEB for non-corn or soy biofuels is roughly equal to that of corn, and the NEB ratio for corn ethanol is exceeded by every other potential biofuel source. Most importantly, the biomass electricity, ethanol, and synfuel are all sourced from a low-input (no tillage, pesticides, or herbicides) high-diversity prairie grassland, replanted on agriculturally degraded soils (that is, they can no longer support food production).

The magnitude of this conclusion cannot be overstated, as it shows how a restored, diverse grassland can provide as much and more energy per degraded hectare than the intensive, energy expensive production of corn. This study exemplifies the care we must take in analyzing proposals by elected leaders and industry – solutions that are reasonable and sustainable are abundant, and need only be considered on balance with the prevailing status quo to show their likely success.

Our energy future will depend on a whole swath of potential and known fuel resources. Corn ethanol may serve in a transition to sustainable fuels, but maintaining food production and security while providing energy will only be possible with concerted, diversified effort. A sustainable biofuels industry will propel America into the future.