Many Americans concerned about pollution are demanding cleaner supplies of energy. The demand has resulted in increased research about ethanol fuel. Ethanol is an alcohol that can be mixed with gas. It burns up most of the pollutants in gas. It replaces some of the chemicals that are known to cause cancer, and it can be produced in the United States. Some experts say that in the future ethanol will replace some of the oil imported into America. Today ethanol is less than one percent of total American fuel supply. The head of the National Corn Growers Association, Kieve Hard, says ethanol will provide twenty-five percent of the fuel supply by 2030. The organization is involved in the production of ethanol because it can be made from corn. One company in the American Midwest says it is starting to produce ethanol because of demands from people and from the government. The Congress approved the Clean Air Act in 1990. The company says this means the market for ethanol will expand. The company is a major producer of corn starch that can be used to make ethanol. At Texas A and M University Professor Mark Holzapple produces ethanol from materials found in solid waste. He has developed a way to turn materials like paper into simple sugar. He then uses yeast to turn the sugar into ethanol. Professor Holzapple says two hundred liters of ethanol fuel can be produced from one ton of solid waste. A professor at the University of Arkansas, John Geddie, is exploring another way to make ethanol. He is using acids on paper material. He says a large factory could produce ethanol from waste paper at a cost about the same as the cost of producing gasoline. Environmentalists support the use of ethanol because it turns solid waste into a useful product. Professor Holzapple says law makers in industrial nations need to support the development of this clean, less expensive fuel of the future. The author mentions all of the following resources for making ethanol except  _  .
corn starch natural gas waste paper solid waste