Why cellulosic ethanol will not save us?

[Editor’s note: This is the next-to-last piece in our series on the Prop. 87 “oil tax.” Tad Patzek discusses the problems with biomass, which is one of the alternative energy sources the oil tax would fund with research.]

Today it is commonly believed that burning freshly cut plants is morally superior to burning old fossil plants. Even more curiously, some are convinced that stripping ecosystems of gigantic quantities of biomass can go on year-after-year, forever, and with no consequences.

This attitude is best exemplified by the DOE/USDA 2005 report by Perlack et al.: “…An annual biomass supply of more than 1.3 billion dry tons can be accomplished with relatively modest changes in land use and agricultural and forestry practices.”

Much of Proposition 87 is built around this delusionary DOE/USDA vision. In his April 2006 presentation, Mr. Khosla proclaimed that US would produce 130 billion gallons of ethanol per year from the imaginary 1.3 billion tons of biomass. Unfortunately, this is impossible regardless of technology.

To arrive at its conclusions, the DOE/USDA report made the following assumptions:

1. Yields of corn, wheat, and other small grains were increased by 50 percent;
2. The residue-to-grain ratio for soybeans was increased to 2:1;
3. The harvest technology was capable of recovering 75 percent of annual crop residues;
4. All cropland was managed with no-till methods;
5. 55 million acres of cropland, idle cropland and cropland pasture were dedicated to the production of perennial bioenergy crops;
6. All manure in excess of that which can applied on-farm for soil improvement under anticipated EPA restrictions was used for biofuel; and
7. All other available residues were utilized.

If these assumptions were not so frightening, they would be laughable:

1. The permanent 50 pecent increase of all crop yields is impossible. The all-time record yield of corn in 2004, 160.1 bushels/acre, was followed by 147.9 bu/acre in 2005, and an estimated 153 bu/acre in 2006. The real yields have been decreasing instead of jumping up by 50 percent.
2. The 2:1 residue-to-grain ratio for soybeans would require a 45 percent increase of the current average harvest index of 0.42, and is not quite achievable.
3. Taking most residues from the fields would leave little or no plant matter to protect the soil from excessive wind and water erosion. The rate of erosion in US agriculture generally exceeds the rate of soil mineral deposition and humus generation.
4. Total no till agriculture would require astronomical quantities of herbicides and pesticides to kill off the “spurious” life competing with the resource-greedy, but otherwise delicate hybrid crop monocultures. Because of the comprehensive loss and poisoning of the natural environment and imported parasites, the honeybee population declined by 60% between 1947 and 2005. Honeybees had to be imported from outside North America last year for the first time since 1922. Bees pollinate an estimated 10-20 billion dollars worth of crops every year.
5. US corn grows on 70 million acres. Dedicating 55 million acres to switchgrass would eliminate plenty of other crops. The total area of the soil Conservation Reserve Program (CRP) in the US is a modest 34 million acres.
6. The EPA requirements are perceived as restrictions. In other words, a modicum of conservation is viewed as an obstacle to feeding our thirsty cars and all remaining land (see Item 5) must go.
7. To utilize all residues, I suggest to also process fresh corpses into biofuels.

One simply cannot remove biomass and nutrients from an ecosystem without putting these nutrients back, protecting the soil structure, and suffering from lower yields in later crop rotations in industrial plantations. The high heating value (HHV) of 1.3 billion tons of biomass is roughly 22 EJ; and the HHV of 130 billion gallons of ethanol is 11.4 EJ. The fictitious DOE energy efficiency of converting biomass to ethanol, 11.4/22 = 0.52, corresponds to Fischer-Tropsch synthesis and is two times higher than efficiency of the current corn-ethanol process. If one were to produce cellulosic ethanol with a 26% efficiency, one would have to use all above-ground biomass of all US crops, pastureland and rangeland, and annual biomass growth over 2/3 of all US forestland and timber plantations.

In summary, the DOE-USDA-Proposition 87 vision is to capture in real time most of net growth of all biomass in the US, while at the same time mining soil, water, and air over 72 percent of our land area, including Alaska, Hawaii, and Puerto Rico. This biomass would then be devoured to feed our inefficient cars. We would have little food production, as well as little wood for paper and construction. In effect, the new brave US economy would be dedicated to feeding cars, not people. This vision has been enthusiastically embraced by some in the US science and industrial establishment.

If one does not buy such obvious delusions and one wants to live better while not destroying the Earth, what is one to do? Instead of stumbling into Proposition 87, it might be better to ask the following questions:

1. What changes of our social and urban infrastructure will be necessary to decrease energy use in the US by a factor of 4-6?

2. How can the public be educated about the inevitable changes of our lifestyles?

3. How can one talk in a sensible way about the complex issues of environment/human interactions? In particular:
(a) How can one formulate the thermodynamics of living ecosystems and bring their descriptions into economic accounting?
(b) How can one consistently compare most energy resources and energy extraction schemes?
(c) How can one quantify the impact of energy supply schemes and life choices on the ecosystems in which we are embedded?
(d) Will there be enough clean air, water, and soil to sustain our society?
(e) How will the progressing global climate change impact energy consumption and production?

The formulation of answers to these questions might start another proposition. That future proposition would be for the people, not their cars.