Biodiesel is considered an environmentally friendly alternative because it reduces the amount of many toxic substances. Plants like soybeans require carbon dioxide from the air to produce stems, roots and leaves. During the production of 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 greenhouse gas emissions does not necessarily contribute to carbon dioxide levels in the atmosphere. This is because 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 occur because biodiesel contains 11% oxygen by weight. Oxygen allows the fuel to burn better, resulting in fewer unburned fuel emissions. And finally, biodiesel fuels do not contain sulfur and do not have an unpleasant odor when emitted from vehicles. Pure biodiesel showed a significant decline in all its harmful chemicals except NOx when...