MAE 124/ESYS 103:  Week 8 Assignment

The Biofuels Debate: Use the Existing Infrastructure or Develop a New Transportation System?


The week 8 assignment asks you to think carefully about biofuels in the context of a life cycle assessment. Biofuels are made from plant crops or algae that is converted to be roughly equivalent to petroleum-based fossil fuels. Their environmental advantage is that the carbon in the biofuel has been removed from the atmosphere only recently, when the plants grew, so burning biofuel simply cycles that same carbon back into the atmosphere with no net longterm increase in atmospheric CO2 concentrations. Or at least that's the idea.

Proponents of biofuels point out their major advantage: they can be used with our existing transportation infrastructure. With biofuels, you can imagine driving the same car you currently drive and buying fuel for it at the same gas station you currently patronize. Not surprisingly the oil industry has begun to invest heavily in biofuels. (See Chevron's comments on the issue.) Opponents are quick to point out their disadvantages: producing biofuels, particularly from corn, represents an inefficient use of limited agricultural land that may lead to escalating food prices. In some cases raising the crops may require more fossil fuel than will actually be generated from the biofuels. Moreover, biofuels can be corrosive so may require significant readjustment of engine components. (Or more specifically, straight vegetable oil and biodiesel will erode rubber---thought not be a problem for most modern diesel engines. Ethanol, and the E85 gasoline/ethanol blend sometimes used as fuel, are noted for being corrosive for rubber, plastics, and some metals.)

How can we, as a society, decide whether to pursue biofuels (and keep our existing cars and airplanes) or to pursue alternative transportation strategies? Write a careful discussion (in no more than 250 words) explaining how we can find good answers for this question. In this particular assignment, we are more interested in having you think through the process of gathering information to make a decision rather than in your actual stance on the issue. You do not need to take a particular position. Instead you should think carefully about the key components of a life cycle assessment that could address this question.

To help you focus on these questions we've asked you to read three very recent articles that focus on some of the central issues:
  1. Campbell, J. E., D. B. Lobell and C. B. Field, 2009. Greater transportation energy and GHG offsets from bioelectricity than ethanol, Science, DOI: 10.1126/science.1168885. A commentary was also published on this article, which you may find helpful: Robert F. Service, 2009, ScienceNOW Daily News. In this study, which was widely reported in the media, the authors carried out a life cycle assessment to compare burning biofuels in cars with an alternative scenario in which biofuels were used to generate electricity, and consumers drove electric cars.
  2. Squatriglia, C., 2009, "Better Place unveils an electric car battery swap station", Autopia blog, Wired, 13 May 2009. This article explores one of the most serious challenges of driving an electric car: how do you travel long distances?
  3. Grammling, C., 2009, "As Green As It Gets: Algae Biofuels", EARTH Magazine, 13 February 2009. Although much of the debate about biofuels has focused on corn and switchgrass, this article considers new 3rd generation biofuels, which are created from algae.
Of course there's plenty more on the topic if you want to keep reading. Here are a few additional articles that might be interesting:
  1. Cassman, K. G., 2008, "Biofuels or Food?: Can Crops Feed Our Cars--And the Hungry?", Scientific American, October 2008. The question of food versus fuel has been debated extensively. This article articulates some of the concerns.
  2. Pimentel, D. et al, 2009, "Food Versus Biofuels: Environmental and Economic Costs", Human Ecology, 37, 1-12, doi: 10.1007/s10745-009-9215-8. David Pimentel has been involved in a number of recent studies that have aimed to evaluate the true economic and energy costs of producing biofuels. Check the reference list of this paper for further examples. Science News coverage of the article summarizes the key points.
  3. Demerjian, D., 2009, "Aviation Biofuels: More Hype Than Hope?", Autopia, Wired, January 8, 2009. Airlines have carried out some high profile demonstrations of bio-jetfuel, but whether they can actually run entirely on bio-jetfuel remains a topic of debate.
  4. And of course, we would be remiss not to draw your attention to this recent item: Shatkin, E., 2009, "The car that runs on bacon", Daily Dish food blog, Los Angeles Times, May 13, 2009..