Biofuel Feedstock

When analysing the potential of biofuel, one of the prevailing questions is whether or not there is sufficient land on earth to deliver adequate food if substantial percentages of land are allocated to biofuel crops. In our report earlier this year “Cellulosic Ethanol” it is clear, in the U.S. at least, that while substantial quantities of ethanol per year may eventually be refined from municipal waste streams, crop residue, winter cover crops, and forest thinning, in order to completely replace petroleum-based transportation fuels, dedicated energy crops will also be necessary. So is there enough land?

One of the key variables often overlooked when asking this question regards yield per acre – not only for energy crops, but for food crops. For example, new strains of dedicated energy crops such as miscanthus, switchgrass and sorghum are already yielding 12+ tons per acre, which at 100 gallons per ton translates into 1,200 gallons per acre. By contrast, first generation distillation of corn ethanol is only yielding about 400 gallons per acre. Several experts, including Dr. Richard Hamilton, CEO of Ceres, Inc., a Southern California based company who is genetically engineering energy crops, and also Vinod Khosla of Khosla Ventures, the noted venture capitalist who has invested in several biofuel companies, maintain the yields of dedicated energy crops can go as high as 25 tons per acre. This would equate to 2,500 gallons per acre, or 38,000 barrels per square mile per year.

This is a dramatic contrast – the difference between what dedicated energy crops yield today vs. where they might go within a generation. To replace roughly 30 billion gallons of petroleum per year, which is current global consumption, using distilled corn at a rate of 400 gallons per acre would require nearly 5.0 million square miles of land; using refined cellulose from dedicated high yield energy crops at a rate of 2,500 gallons per acre would require about 750,000 square miles of land. This is still a staggering amount of land, but given there are about 10 million square miles of arable farmland on earth, it is not an unthinkable amount of land to allocate to energy crops – particularly since ethanol and other transportation fuels will also be sourced from waste streams and other sources. So is there enough land?

The answer depends on what assumptions one makes regarding yields per acre for food crops. And in this area the data indicates surprising potential for yields worldwide to register sharp increases in the coming years. Despite the often heard suggestion that we have already had our global revolution in yields (the first “green revolution”), there is still a vast disparity between yields using modern agricultural techniques and modern strains of crop seed, and the yields using traditional subsistence agriculture. Crossing this gulf by bringing significant portions of the world’s agricultural land into the 21st century would completely eliminate food scarcity.

For example, corn yields in the USA in 2005 averaged 149 bushels per acre. The global average, however, was only 75 bushels per acre. Agricultural powerhouses such as Brazil and Argentina, respectively, only averaged 54 bushels per acre and 109 bushels per acre. Technologically advanced nations with the capacity to increase yields if they prioritized this effort, such as China and India, only delivered 80 bushels per acre, and 31 bushes per acre, respectively.

Another way of analysing this is to compare the global average yield for major food crops as a percentage of the commercial yields being delivered by the top 10% of acreage for that crop. The figures, again, are dramatic: For corn, the global average yield is only 29% of the average yield by the top 10% of corn producing acreage; for wheat, 38%; for rice, 43%. Major grain crops worldwide have the potential to increase their yields sufficiently to easily feed 9.0 billion people simply by adopting 21st century techniques. As Richard Hamilton at Ceres puts it, “we don’t have a shortage of crop land, we have a shortage of agricultural technology.”

Clearly there are issues with food production that go beyond land – ensuring adequate irrigation and addressing concerns about genetically modified crops, for example. But these modern crops are designed to replace nutrients in the soil and deliver these high yields with relatively minimal water inputs. Nations that embrace modern agricultural methods are likely to experience food abundance as well as have land left over to allocate to energy crops – a prospect so positive in its humanitarian implications perhaps it may stimulate another, more balanced look at the risks and benefits of genetically modified crops.

Commercial yields of corn per acre now routinely
exceed 160 bushels per acre, but advanced test crops are
actually delivering yields as high as 300 bushels per acre.
(Source: Ceres, Inc.)

One Response to “Biofuel Feedstock”
  1. Linda King says:

    October 14, 2008
    With all of the discussion based around food crops for biofuel and concern about the number of acres required, I would be interested in knowing if it would be possible to process Kudzu for fuel. The Southern and South Eastern United States is virtually overrun by Kudzu. It grows at an extremely rapid pace and is almost impossible to kill off or even prevent from incursion into new areas. Has this idea been looked at by anyone in the biofuel studies industry?
    Thank you,
    Linda King


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