9．Going soy is the way to go green
In 1829，U．S．farmers grew soybeans （大豆） for the first time．In the late 1800s，lots of farmers began to grow soybeans as food for cattle．In 1904，at the Tuskegee Institute in Alabama，George Washington Carver began studying the soybean．His discoveries changed the way people thought about the soybean．No longer was it just a crop for cattle； it provided valuable protein and oil．Now soybean oil is the most popular source for an alternative fuel．
Fueling diesel （柴油） engines with vegetable oil started with the inventor Rudolf Diesel．When Diesel showed his engine at the 1900World Exhibition in Paris，it was running only on peanut oil，a kind of biodiesel．According to the United Soybean Board，biodiesel is a fuel made from vegetable oils or animal fats．
However，over the next 100years，diesel fuel was made largely from petroleum （石油）．Interest was renewed in biodiesel in the mid-1970s when the energy shortage occurred，and gas prices surged upward throughout the United States．In spite of these conditions，commercial production did not take place until much later．In 1999，The National Biodiesel Board reported that 500，000gallons per day were produced．In 2000，production increased to 6.7million gallons per day．
With the continual rising costs of petroleum products in the new century，major corporations and the United States government have looked to new markets．Farmers are encouraged to grow soybeans in their fields，as the demand for soybean fuel increases．They can now get several gallons of fuel per acre of soybean．
Biodiesel is created by removing a thick liquid called glycerin from soybean oil．It is registered with the US Environmental Protection Agency as a pure fuel，which is known as B100，or as a fuel additive，which is called B20，a mixture of 20percent soy and 80percent petroleum-based diesel．
There are many benefits of soybean fuel．
Studies have shown that biodiesel from vegetable oil reduces petroleum consumption when used in place of petroleum diesel．
In addition，the use of biodiesel reduces CO2in the earth's atmosphere．This is due to the fact that growing soybeans consumes nearly four times as much CO2as the amount of CO2produced from biodiesel waste gases．
If you ever want to take a ride in a car or bus powered by soybeans，you can．The Agriculture Research Center （ARS ） National Visitor Center bus，which is used for Beltsville，Maryland farm tours，is running on biodiesel fuel．
ARS scientists are conducting biodiesel fuel research，and they are trying to find ways to make fuel from vegetable oils，animal fats，and used restaurant oils．
Biodiesel fuel costs more than regular diesel fuel．However，the price may drop if people use it more．We can look to the future with the hope that clean fuel sources will continue to be widespread in the United States and even around the world．
