Growing Fuel? Not with food crops.

Notice I'm not piling on and writing about the Gulf Oil Spill.  It is worth noting in passing that even if the spill amounts to several million barrels over several months, that will still only come to a tiny sliver of the world's 85 million barrels per day of consumption.  And that ties to my real topic for this post.

I asked a friend of ours who studies the world food supply how much food in calories the world produces.  Joel sent me some numbers and a recent report by the Food and Agriculture Organization of the United Nations.

In 2009, the world produced 2.2 billion metric tons (mt) of cereal grains, 0.4 billion mt of oil seeds, 0.16 billion mt of sugar, 0.29 billion mt of meat, and 0.14 billion mt of fish.  Since most of the meat was made by feeding the cows and pigs the cereal grains, lets drop those out.  And I'm skipping dairy, since it's mostly water.  So the world produced about 2.9 billion mt of food in 2009.  I wondered how much of that is usable energy.  A study I came across at the University of Florida, puts the metabolizable energy in wheat, corn, and soybeans all at about 1500 calories per pound.  Since those grains make up the biggest share of the 2.9 billion mt, that gives us a ballpark figure of 9.57 quadrillion calories produced in 2009.  A barrel of oil has approximately 1.39 million calories of energy.  So at about 31 billion barrels of oil a year st current rates of consumption, that's 43 quadrillion calories of oil per year.

That means there's over 4 times as much energy in the oil we burn in a year compared to the food we grow in a year.  Can we expect ethanol produced from food crops like corn or even sugar cane to provide a significant fraction of our transportation energy requirements?  David Pimental, a respected ecologist at Cornell University, has performed extensive analyses of biofuels, especially corn.  He summarized his work last year in the Harvard International Review.  You should go read the article for yourself, but he calculates that if all the corn grown in the U.S. in a year could be made into corn ethanol, it would provide only 4% of our energy consumption.  But that's not taking into account the whole energy budget, I think.  Last year, we used 33% of our corn production to produce 9 billion gallons of ethanol, which only has about 2/3 the energy of gasoline.  The works out to the equivalent of 143 million barrels of oil, which sounds decent.  However, since the most optimist estimates of the amount of energy put into corn versus energy back is 1.3 to 1, that means we burned 109 million barrels of oil to get the corn ethanol.  That leaves 34 million barrels of oil equivalent.  The U.S. uses 20 million barrels of oil per day.  So we used 1/3 of a year's corn crop to produce slightly less than a 1.5 days of transportation energy.  Using all the corn would only give us 1.3% of our energy needs for the year.

Obviously, trying to pour our food into our gas tanks won't get us very far.