By David L. Brown
My associate Val Germann and I have discussed the issues of ethanol and biofuels fairly often here on Star Phoenix Base. It is not necessarily that this subject is of unusual interest to us, but more because there is a mad rush of “irrational exhuberance” concerning this subject. It all seemed to start with President Bush’s State of the Union address when he spoke of “switchgrass” as the future replacement for imported petroleum … an unlikely idea that has apparently encouraged vast numbers to jump on board this perceived profit bandwagon.
Of course, the production of ethanol from corn has been going on for some time. This is a fairly well established, if none too efficient process. It has its start during the 1970s, when overproduction of agricultural products, and in particular field corn, was a problem and OPEC was squeezing the West by creating artificial oil shortages. Surplus corn could be used to make alcohol, which could replace oil. Brilliant!
But massive grain surpluses are no longer a problem; quite the contrary as agricultural production is bumping up against steadily rising demand (in case you weren’t watching the world population has approximately doubled since the 1970s). That fact makes it rather troubling that there is now surging interest in converting food grains and devoting agricultural lands to the production of a rather second-best alternative to gasoline.
Several recent articles and an editorial in Science Magazine discussed the “bright future” for ethanol and biofuel programs. We felt these articles were a bit too optimistic to say the least, and apparently there are others who agree with us. Those articles have generated quite a few letters to the editor of Science that point out some of the false assumptions and misguided reasoning behind the biofuel mania. A number of those letters appeared in the current issue.
Many of the points raised by correspondents have already been made here, but for the enjoyment and edification of our readers we are pleased to pass on excerpts from some of those letters. First here is a passage from a letter signed by five Danish agricultural scientists:
We believe that bioenergy production and policies need to be based on a broad cost-and-benefit analysis at multiple scales and for the entire production chain. This is particularly true for bioenergy’s impact on agriculture. One of the major problems in modern, intensive agriculture is the lost link between livestock and land. This separation between different agricultural production systems, environmental problems, and the consumers is largely unaccounted for in the development of economies and agricultural practices. Mitigation actions are needed to ensure global sustainability. It is possible that growth in bioenergy production will add to these problems, reducing the overall benefits of conversion. … Ecologically sound bioenergy production should aim for closed cycles of mass and optimization of net energy yields and efficiencies.
Next came a scathing analysis of the real cost and ethical considerations involved in utilizing potential food crops or converting potential agricultural lands to produce biomass, from two agricultural scientists, David Connor of the University of Melbourne, and Ines Minguez of the Universidad Politechnica de Madrid. They conclude that the irrational exhuberance surrounding this issue is…
… arousing unreasonable expectations for its potential contribution to energy and environmental goals. Although biofuel’s contribution can be positive, it will remain small, being restricted by the ability of the natural environment to provide both fuel and food for a large and energy-demanding world population.
It requires production equivalent to 0.5 ton of grain to feed one person for one year, a value sufficiently large to allow some production to be used as seed for the next crop, some to be fed to animals, and some land to be diverted to fruit and vegetable crops. Compare this value with that for a car running 20,000 km/year at an efficient consumption of 7 liters/100 km. The required 1400 liters of ethanol would be produced from 3.5 ton grain (2.48 kg grain/liter), requiring an agricultural production seven times the dietary requirement for one person.
Agriculture now provides, with some shortfalls, food for 6 billion people and will need to feed 9 billion by 2050, while conserving natural resources. From an agronomic perspective, increasing food production to this level during the next 50 years is an enormous challenge.
The above calculations demonstrate that major reliance on biofuel, even for private motoring alone, would place an additional demand on agricultural production greater than would providing an adequate diet for 9 billion people by 2050. Positive energy gain and reduced greenhouse gas emissions are not sufficient to establish biofuel as an economic and ecologically friendly solution to current problems of energy supply and ecological sustainability. Anything but a marginal contribution from biofuel would pose a serious threat to both food security and the natural resource base of land, soils, and water.
Startling analysis, and makes clear the conflict and ethical divide between the mutually exclusive issues of how to feed a hungry and growing population and the desire to create fuel from biomass or crops. Next, Science received a sharp note from Kay Brower, Dept. of Chemistry (Emeritus), New Mexico Institute of Technology:
In a sophisticated journal such as Science, we expect the topic of energy policy to be illuminated by use of arithmetic and other analytical tools. The Review “The path forward for biofuels and biomaterials” … presents its most important datum, 1020 joules per year of sustainable biomass energy, without any attempt to relate it to energy consumption. [Here Brower presents some calculations leading to the following conclusions] For itself, the United States would use approximately 40% of the world’s biomass energy just for electricity. The remainder of the energy, and more besides, would be consumed by transportation, space heating, and manufacturing. Nothing would be left over for the rest of the world. Because wind and solar energy have less potential than biomass energy, it is obvious that the global community must rely mainly on petroleum and coal.
In his letter, botanist Michael W. Palmer of the University of Oklahoma recognized the potential of switchgrass, but raises qustions about the sustainability of a monoculture regime:
… Switchgrass (Panicum virgatum), which grows naturally throughout most of the continent, is a promising source material. The prospect of a native grass dominating an agricultural landscape is intriguing and potentially ecologically sound.
In nature, however, switchgrass almost invariably grows intermixed with other C4 grasses such as bluestems. It is unclear whether vast monocultures of switchgrass can be sustainable, especially given that pathogen sources are likely to be present in natural populations of this species. It is also not clear whether these other C4 grasses may be promising candidates for biofuels.
Three environmental scientists, Cutler J. Cleveland et al., examine the EROI (energy return on energy invested) for biofuels, suggesting that the return could likely be a near-wash:
In their Report “Ethanol can contribute to energy and environmental goals” A. E. Farrell et al. focus in part on whether biomass-derived ethanol fuel delivers positive net energy [i.e., whether energy return on energy invested (EROI) exceeds 1:1… Their analysis neither resolves nor clarifies the fundamental issues that make net energy important and contentious. First, in their comparison of ethanol and gasoline, they confuse EROI–a productivity index–with the energy efficiency of an oil refinery. Second, their use of energy break-even as a litmus test is a red herring; it is more crucial that EROI is high compared with competing energy sources. Exploration for domestic petroleum in the 1930s returned 100 Joules for each Joule invested; the EROI for oil production today is ~15:1… Because the present EROI of fossil fuels is high, the ~90 net Quads (1 Quad = ~1 exajoule) delivered annually to the U.S. economy results from an investment of only about 10 Quads … To provide that same 90 net Quads from corn-derived ethanol would require an investment of 145 to 500 Quads (based on an EROI = ~1.6:1 to 1.2:1, implied by Farrell et al.‘s fig. 1). The current transportation system cannot be maintained on a fuel system delivering only a 1.6:1 return. Third, the focus on petroleum inputs is too limited. Natural gas is often the principal input to biomass fuel production, but its future is no more certain than oil’s; we already import more than 15% of what we use … Fourth, the authors ignore the energy cost of repairing soil erosion.
Finally, the one (speculative) result for an energy technology based on cellulose in fig. 1 implies an EROI of ~50:1. This (very uncertain) EROI indicates that this source of biomass could be potentially useful, but ethanol from corn remains too marginal to survive without heavy economic subsidy.
Yet another trio of scientists from the University of Vermont, Nathan Hagens et al., add to the questions concerning the EROI, raising the significant question of whether there is even a net gain from converting corn into ethanol. When all factors are taken into account, they do not seem to believe so:
… If replacing oil is our goal, we must look at two parameters of this approach: (i) energy return on investment (EROI) including environmental impacts on soil, water, climate change, ecosystem services, etc.; and (ii) scalability and timing. Farrell and colleagues’ most optimistic EROI of 1.2:1 (which does not include tractors, labor, or environmental impacts) implies that we need to produce 6 MJ of ethanol to net 1 MJ of energy for other endeavors. Thus, the yield of ethanol would not be 360 gallons per acre gross yield, but rather a mere 60 gallons per acre net yield, not even two fill-ups for an SUV. The entire state of Iowa, if planted in corn, would yield approximately five days of gasoline alternative.
To devote half the nation’s corn crop to ethanol would require an input of 3.42 billion barrels of oil (almost half our current national use) to net 684 million barrels of “new” ethanol energy. We would also lose food and soil nutrients, suffer ecosystem damage, and use massive amounts of water for irrigation.
We need alternative energy. But ethanol from corn is neither scalable nor sustainable. Let’s pursue better options.
On the same topic, Robert K. Kaufman of Boston University adds this:
… The energy used to produce motor gasoline is much less than its energy content–estimates for the total energy input/energy output ratio are about 0.06.
For biomass fuels, the authors report only the petroleum input/output ratio. Other fuels used in the process should also be included; these cannot be assumed to be sustainable (as exemplified by natural gas shortages) The biomass fuels are not used as liquids–(much of the co-products are used to generate electricity), which also needs to be taken into account. Including these additional fuels raises the input/output ratio to 0.79 (ethanol today) or 0.82 (CO2 intensive). If the U.S. economy used oil with an energy input/output ratio of about 0.8, the energy equivalent of about 80 million barrels per day of oil would be used to generate the 20 million barrels per day of refined petroleum products that the United States uses outside of the oil sector.
Once the boundaries are made equivalent, motor gasoline has a much higher energy surplus and a lower energy input/energy out ratio than biomass fuels. This result matches the economic reality described by the authors’ first paragraph–biomass fuels, not motor gasoline, need subsidies and tax breaks.
Tad W. Patzek of the University of California, Berkeley, adds:
… Most of the current First Law net-energy models of the industrial corn-ethanol cycle are based on nonphysical assumptions and should be discarded.
When properly formulated, mass and First Law energy balances of corn fields and ethanol refineries account for the photosynthetic energy, some of the environment restoration work, and the co-product energy. These show that production of ethanol from corn is two to four times less favorable than production of gasoline from petroleum. From thermodynamics, it also follows that the ecological devastation wrought by industrial biofuel production must be severe. With the DDGS [dried distillers grains] co-product energy credit, 3.9 gallons of ethanol displace on average the energy in 1 gallon of gasoline. Without the DDGS energy credit, this average number is 6.2 gallons of ethanol. Equivalent CO2 emissions from the corn ethanol cycle are 50% higher than those from gasoline and become 100% higher if methane emissions from cows fed with DDGS are accounted for.
So, here are a number of sound reasons why the United States would be wise not to base its future energy strategy on the hope of producing vast quantities of “gasoline” from our agricultural fields. It would be insanity to create a world food crisis while pushing up food prices for U.S. consumers, all in the name of replacing a far more efficient feedstock (petroleum). Sadly, as we have noted before, there are no easy answers to our future energy needs, and while biofuels and ethanol may have a very limited place in that matrix, we must not allow ourselves to be carried away on the shoulders of irrational exhuberance that is sure to lead to the inevitable economic crash which seems to follow bubbles as surely as thunder follows the lightning (see my article “Madness of Crowds Surrounds Ethanol Bubble”).