Biodiesel is created through the transesterification of fat. In basic terms, animal fat is mixed with vegetable oil and alcohol to produce biodiesel. Biodiesel comes in any mix, but the four standards are 100% (B100), 20% (B20), 5% (B5), and 2% (B2). Blends of 20% or less can be used in diesel equipment without modification. Over 20% and engines often require modification to maintain performance. Like bioalcohols, biodiesel can corrode rubber in fuel lines and plastics in other locations. As a result, engines should be modified prior to the use of biodiesel. Most manufacturers currently produce diesel engines to run on biodiesel.
Biodiesel has several advantages over petrodiesel, the first of which is that it is renewable. It is also better for the environment in that it produces 57% less greenhouse gas than standard petro diesel.
Biodiesel is actually a better lubricant and reduces fuel system wear in vehicles. Until recently, it was cheaper than petrodiesel as well. Because it is not toxic, biodiesel can be made on site, which is often the case on farms. This leads to reduced costs for farmers.
There are several disadvantages to biodiesel. In terms of utilization, it can gel at low temperatures and it is prone to water contamination. Both gelling and water contamination can lead to harder starting of engines by reducing the heat of combustion. Water also promotes the growth of system clogging bacteria and can cause pitting of the pistons within the engine. Both of these problems are relatively easy to overcome.
Less simply solved is the problem of production. If all arable land in the U.S. were devoted to biodiesel production, it would yield just enough to meet current demand. That includes only vehicles that currently run on diesel and does not make room of any growth in demand. This leaves no arable land for food production.Currently, systems that utilize algae are being devised and may offer a solution to the problem. Algae contain nearly 10 times the amount of oil per volume than traditional sources. As it stands, biodiesel only accounts for about 1% of total diesel consumption in the world. Recent changes in the petroleum markets have resulted in biodiesel costing slightly more than petrodiesel.