Monday, August 27, 2007

How Sweet it Is! Chinese Sorghum-Based Ethanol

China has chosen sweet sorghum--a somewhat neglected alternative to corn, sugar cane and sugarbeets--as the primary feedstock for the nation's emerging ethanol industry.

Chinese officials say sweet sorghum stalks (imagine corn without the ears) will initially be used to produce more than a billion gallons a year of ethanol. The output is likely to increase as more land is allocated to cultivation of the sugar-rich, cane-like plant that thrives under dry, warm conditions, and can even be grown on marginal lands. It has been called "a camel among crops" because of its marked resistance to drought.

Sweet sorghum is currently being used in India, South America, the United States (in eight plants and a few experimental facilities), and the Philippines to produce ethanol.

Experience indicates that production of ethanol from sugar cane and sweet sorghums are basically similar. But sweet sorghum seems to have several comparative advantages, including: a shorter growing period; low fertilization and water requirements; and the fact that it can be harvested mechanically.

In a typical sweet sorghum system, the crop is harvested, after which the stems are crushed and the juice is extracted at a mill, similar to sugar cane. Some harvesters are available to extract the juice in the field and leave the residue, called bagasse, in the field to be gathered at a later time.

Once the juice is extracted, it is fermented and ethanol is produced. This ethanol is then distilled and dehydrated using the same equipment that is being used in ethanol production from grain sources.

In the US, sweet sorghum has been widely cultivated since the 1850s for use in sweeteners, primarily in the form of sorghum syrup. By the early 1900s, the US produced 20 million gallons of sweet sorghum syrup annually. Currently, less than one million gallons are produced annually in the US. Most sorghum grown for syrup production is grown in Alabama, Arkansas, Georgia, Iowa, Kentucky, Mississippi, North Carolina, and Tennessee. Sorghum syrup and hot biscuits are a traditional breakfast in parts of the South.