Using biodiesel instead of petroleum diesel is better for the environment and its better for us! Overall, biodiesel is a fairly renewable fuel. If crops are grown for the purpose of making biodiesel (generally called energy cropping), then any emissions given off by combusting the biodiesel will be sequestered by next year's crops. In this sense, biodiesel is a carbon neutral product. However, energy must be expended to produce it, and methanol, a catalyst commonly used in biodiesel production, is generally derived from natural gas.
With these considerations in mind, biodiesel represents a transitional fuel that can help reduce emissions from diesel consumption and lessen our dependence on the finite supply of petroleum.
Overall, biodiesel significantly reduces emissions of almost every major pollutant when compared to conventional diesel. This means cleaner air for all of us!