Biodiesel is mainly used in diesel car and truck engines, although it can also be used for heating and other needs. The technology has been developed to allow biodiesel to be used for airplanes and trains as well. Major leaps have been met in the advancement of biodiesel fuel that will power stronger engines. Not only does the biodiesel have the obvious advantages of being more environmentally friendly with less pollution, but it also comes from renewable sources. By utilizing natural forms of fuel such as various plant oils and animal fats, sources of biodiesel can be re-grown. 
The major definition of what exactly biodiesel is basically any non-petroleum fuel which can be used in the same way that diesel can. Most variations of biodiesel are actually blends of biodiesel and diesel petroleum. When using this type of mixture, the biodiesel helps to clean out the engine that it is being run in. This increases the total performance of the engine. It runs much cleaner which also expands the life expectancy of the engine.
Another major use for biodiesel fuel technology is for heating homes. Instead of using pure oil, one can have a mixture of biodiesel put in to increase efficiency. Because of the ingredients of the biodiesel and how it burns, many of the lingering deposits left from burning regular oil will clear out of the heater's system fairly quickly. While this is great for the system in just about every respect, a person will have to spend a bit more energy and time making sure that the filters remain clear and able to work. The stuff that the biodiesel cleans out of the engine or heater will need to be removed promptly to ensure that it does not clog up.
The sources of biodiesel, though renewable in nature, are still limited for major use. Considering how much plant oil is needed to be able to take the place of gasoline in the amount consumed, the available land and fresh water needed to produce the biodiesel is just not there. Though, by changing what types of plants and oils are used, the industry may be able to concentrate the growing of oil rich plants in specific areas to increase the actual amount of biodiesel.
Many areas are actually requiring that biodiesel be available to drivers who are running their cars with the alternative type fuel. In some instances biodiesel is actually more economical for drivers to use, as it is priced cheaper. There are also city municipalities are running their vehicles such as buses and other city cars only on biodiesel fuel. In areas which pollution is a major factor, the use of biodiesel is helping to diminish the emissions which are produced by drivers.
Future development of biodiesel fuels will apply to everyday transportation of every kind. As of this point, airplane and train biodiesel use is not mainstream. As sources of the fuel continue to become more plentiful, so will the applications that biodiesel will be used for.