Bio-Fuel

                                                                  BIO FUEL

Biofuels are fuels largely derived from living organisms that use the sun as their main energy input. Energy may be put into planting, fertilizing, harvesting, and processing the crops, but most of the energy, in the final plant product, comes from the sun. Through the process of photosynthesis plants convert solar energy into chemical forms of energy (carbohydrates, fats, etc.). Plant convert solar energy into a chemical form more usable as a fuel. Biofuels are considered carbon neutral. That is, they release no net amount of carbon dioxide into the atmosphere.This because the carbon dioxide that is released during combustion was originally absorbed from the atmosphere during the process of photosynthesis.Hence, no extra CO2 is pumped into the atmosphere The process of photosynthesis can be summarised by the equation below.

6H2O + 6CO2 => C6H12O6 + 6O2

Palm oil is used to produce biofuel.  . A process known as transesterification is commonly used to produce biodiesel. Chemically, transesterification is the process of exchanging the alkyl group of an ester with another alkyl group, from a different alcohol. Vegetable oil contains fatty acids bonded to glycerol to form triglycerides. In the case of biodiesel, a vegetable oil ester is combined with a simple alcohol, methanol, and a catalyst, resulting in the breakup of the triglyceride ester to form glycerol and three methyl esters (biodiesel) A typical molecule of biodiesel looks like the structure below.  Mostly it is a long chain of carbon atoms, with hydrogen atoms attached, and at one end is what wecall an ester functional group .

Making good biodiesel requires several other steps besides the transesterification reaction(as shown in the right).  The first is to remove any traces of water in the vegetable oil.  If this is not done, the water will later react with the vegetable oil in the reaction and make soap.

If soap gets made, then later it complicates the steps after the transesterication reaction that are needed to separate the biodiesel from leftover methanol, the NaOH or KOH catalyst, and the glycerol byproduct.Diesel engines can burn biodiesel fuel with no modifications (except for replacing some rubber tubing that may soften with biodiesel).  This is possible because biodiesel is chemically very similar to regular diesel, shown below.  Notice that regular diesel also has the long chain of carbon and hydrogen atoms, but doesn’t have the ester group.Actually, the first diesel engines didn’t run on “diesel” fuel, but on vegetable oil, a sample molecule of which is shown below.  Notice that it also has the long rows of carbon and hydrogen atoms, but is about three times larger than normal diesel molecules.  It also has ester functional groups , like biodiesel.That larger size of vegetable oil means that in cold weather it gels, making it hard to use in an engine.  Converting it into biodiesel makes it a smaller molecule, closer to the size of regular diesel, so that it has to get colder than vegetable oil before it starts to gel.