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Keywords:

  • net energy;
  • megajoule (MJ);
  • ethanol;
  • fossil fuels;
  • metrics

Abstract

As the world shifts away from a dependency on petroleum resources it is imperative that clear and accurate perceptions of the value of alternative fuel sources are recognized. The silly “net energy” argument revolving around fuel ethanol offers a textbook example of how not to think about alternative fuels. For over 25 years a small but vocal group of critics has argued that ethanol from corn has a negative net energy. This viewpoint has been widely disseminated and is a major perceived drawback to ethanol. Net energy analysis is simple and has great intuitive appeal. It is also dead wrong and dangerously misleading. If we are to make wise decisions as we embark on this brave new world of alternative fuels, we will need to carefully choose our metrics of comparison. Two complementary metrics suggest themselves. First, alternative fuels (e.g. ethanol) can be rated on their ability to displace petroleum; and second, ethanol could be rated on the total greenhouse gases produced per km driven. These are appropriate metrics, though there is still room for more discussion. Useless, misleading and dangerous metrics such as net energy must be eliminated from our discourse. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd