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NATURE: Plant-to-oil equations point up unsustainable profligacy

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  • npat1@juno.com
    Calculations illustrate fossil-fuel crisis: Plant-to-oil equations point up unsustainable profligacy.Calculations illustrate fossil-fuel crisis Plant-to-oil
    Message 1 of 1 , Nov 7, 2003
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      Calculations illustrate fossil-fuel crisis: Plant-to-oil equations point
      up unsustainable profligacy.Calculations illustrate fossil-fuel crisis
      Plant-to-oil equations point up unsustainable profligacy. 29 October 2003
      BETSY MASON
      http://www.nature.com/nsu/031027/031027-3.html

      If you burned a litre of petrol on the way to work this morning, consider
      this: it took 23.5 tonnes of ancient, buried plants to produce. That's
      the equivalent of 16,200 square meters of wheat, roots and stalks
      included. So says new research that aims to raise awareness about the
      need to change our energy-consumption habits. The long, slow process that
      converts plant matter into oil is extremely inefficient, says ecologist
      Jeff Dukes of Carnegie Institution of Washington, Stanford, who did the
      calculations. Less than one part in 10,000 of the organic matter becomes
      oil.
      "So much carbon is lost back to the atmosphere through decomposition,
      it's only the residues that are turned into fossil fuels," says Dukes. He
      warns that less than a tenth of the carbon in plants buried in peat bogs
      was turned into coal1.
      In 1997, he points out, we burned fossil fuels equivalent to more than
      400 times the amount of plant matter produced on Earth in the same year.
      Despite these inefficiencies, fossil fuels created over the past 500
      million years have given us a relatively inexpensive fuel source for the
      past 250 years. "It is fantastic stored free energy from the past, but
      it's not sustainable," Dukes says. Modern ways to convert biomass into
      fuels such as ethanol are far more efficient. But it would still take
      nearly a quarter of all the plants on Earth to replace the fuel used in
      1997. That's 50% more than humans already remove or pave over each year,
      says Dukes. "Hopefully we'll use more wind and solar power," he suggests.
      It's a valid point, says geologist Sandra Neuzil of the US Geological
      Survey in Reston, Virginia, who studies peat decomposition. But she is
      cautious about the many unknowns in such equations, saying: "When you
      start multiplying uncertainties the numbers start to become meaningless."
      Dukes acknowledges that his calculations have a large degree of
      uncertainty, but believes he has captured the essence of the process.
      "I'm hoping that it will make people think," he says.
      References
      Dukes, J. S. Burning buried sunshine: Human consumption of ancient solar
      energy. Climatic Change, published online, (2002). |Homepage|
      � Nature News Service / Macmillan Magazines Ltd 2003


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