Biodiesel is a fuel source that is taken from plant based oils or animal fats (tallow). These sources are then converted to useable fuel by creating alcohol through a process known as esterfication and transesterfication.
The emergence of biodiesel isn't a new technology. The aforementioned processes were discovered in the mid-19th century, patented, and working in the 1940's and 1950's. The historical background of biodiesel tells usthat this technology has been around for quite a long time. However, there has always been some barriers to its more widespread use and attractiveness as an alternative energy source to petroleum based diesel and other fuels.
(CC Image of 100% soybean biodiesel (B100) by Leandro Maranghetti Lourenço [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC-BY-SA-1.0 (http://creativecommons.org/licenses/by-sa/1.0)], via Wikimedia Commons)
Biodiesel can be created by using various feedstock sources such as: soybeans, sunflowers, hemp, palm oil, coconut oil, tallow, rapeseed, peanut oil, and other vegetables that can be used to make biodiesel.
One major setback to the widespread use of biodiesel as a replacement or supplemental feedstock to U.S. energy consumption is that biodiesel fuels generally have a higher viscosity than petroleum based fuels. This higher viscosity slows the fuel down (especially in colder temperatures) as it passes through the fuel filter, injectors, etc. This slowing action causes plugging, coking, and build-ups in engine that have left many producers and consumers in the auto-industry weary of the fuel source.
One solution to this problem is that the fuels are often mixed at 2, 5, 20, or more percent with other conventional fuels. This reduces issues with viscosity and build-up. However, other issues are present, such as the cost of refining the fuels, as well as the source of the fuels. In the United States, discount rates and perverse subsidies already exact a toll on our food systems by diverting much of our cropland to soybean and corn production for the use in the meat industry, or to be sold on commodity exchange markets. This conflict of using land for the commodity food crop, animal feed, or fuel source is becoming extent.
(CC Image of 100% biodiesel bus (logo) in Brazil by Mariordo (Mario Roberto Durán Ortiz) (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)