Biodiesel is a substitute for diesel fuels which is used in trucks mostly in the United States. Usually soybean is used in the U.S. Vegetable oil and other natural oils are used to make biodiesel (used cooking oil). No petroleum is necessary but it can be mixed so that you have a blended biodiesel. It is available in all 50 states. It is better for your engine and makes the exhaust smell like french fries.
Benefits:
1) Better for the engine, environment, and human health.
2) New source of income for rural farmers-helps rural economies.
3) Simpler to make than ethanol and can be done right on a soybean farm.
4) Reduce smog, ozone reduction, acid rain, cancer, and asthma.
5) Burns 75% cleaner than normal diesel, reduce carbon monoxide, eliminates sulphur dioxide emissions. Reduction in greenhouse gases contributing to climate change.
Problems:
1) Sustainability issues with growing soybean. Increase of soybean deforestation or environmental changes may occur.
2) The efficiency in making biodiesel is not very good even though it is better than making diesel itself.
3) There are limits on production from land use, water availability, and competition of food crops.
4) Major technological advance would have to occur to completely replace diesel as the leading current source as compared to biodiesel.