Biodiesel is considered an environmentally friendly alternative because it reduces the amount of many toxic substances. Plants like soybeans need carbon dioxide from the air to produce their stems, roots and leaves. When producing biodiesel from soybean oil, carbon dioxide is produced and released into the atmosphere. Carbon dioxide is considered a greenhouse gas (GHG). However, this cycle of GHG emissions does not necessarily contribute to atmospheric carbon dioxide levels. In fact, the next soybean crop will reuse the carbon dioxide emitted for its growth. Another important environmental benefit is that biodiesel reduces emissions of particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO). These benefits are due to the fact that biodiesel contains 11% oxygen by weight. Oxygen allows the fuel to burn better, resulting in fewer emissions from unburned fuel. Finally, biodiesel fuels do not contain sulfur and do not have an unpleasant odor when emitted by vehicles. Pure biodiesel showed a significant drop in all of its harmful chemicals except NOx when emitted....