Can anyone explain to me about the manufacture of biofuel?

Question

What is transesterification?

What is esterification?

Is biofuel expensive?

What are the disadvantages?

Answer 1

"Biofuel" is a large catagory that generally refers to any renewable fuel that comes from a plant-based re-growable source.

Distillation can be used to create flammable liquids (alcohols) from corn or other common crops. These are often mixed in with pump gas (MTBE at 10% or less). Scrap wood from sawmills (from trees that can be replanted and regrown) is commonly burned for fuel.

The problem with biofuels is that they are still burned (as are fossil fuels) to create heat, and thereby release the same amount of CO2 into the atmosphere. Also, it's still more expensive to distill a gallon of alcohol from corn than it is to manufacture a gallon of raw gasoline or diesel fuel.

A gallon of alcohol has about 30% less energy (btu's) than the same volume of gas or diesel, so a car converted to run on alcohol will use more fuel than it did on regular gas.

If you have an engine that will run on corn oil (cooking oil), you can often obtain the fuel for free by visiting fast food restaurants and taking their used oil which would otherwise be discarded. Of course, it needs to be carefully filtered before being poured in the tank, and the resulting exhaust fumes smell like french fries.......

Answer 2

Transesterification is the process by which the alkoxy group is switched with the alcohol of another compound. Esterification is the reaction where two chemicals from an ester, which is a molecule with an oxygen atom inbetween two organic functional groups.

Biofuel is extremely cheap at the moment, but the main disadvantage is that it drives up the cost of consumer products made from corn, which in turn places higher demand on other consumer products, increasing those costs as well.

Answer 3

http://journeytoforever.org/biodiesel_ma...

Answer 4

Esterification is a reaction between and alcohol and an organic acid to form an ester.  Transesterification is the replacement of the alcohol in an ester with different alcohol to form a different ester.

Transesterification is one process for producing biodiesel from fats.  Fats are esters between glycerol (glycerine) and three fatty acids.  In most biodiesel production, the glycerol is replaced by three methanol molecules.  The product from this reaction is know generically as fatty acid methyl ester or FAME.  FAME has many possitive properties relative to its use as diesel fuel:  

It has a high lubricity, and can actually replace synthetic lubricating additives that must be mixed with ultra low sulfur diesel fuel (ULSD).  

It has a high cetane number, which means that it burns well in diesel engines and will produce low levels of soot.

It is essentially sulfur free, which will reduce the emissions of sulfur oxides (a major component of smog and acid rain).j

It also has some drawbacks:

It has a lower energy content than conventional diesel oil, thus you must burn more of it.

It is a strong solvent, which means that it will attack plastic seals and fuel lines, resulting in leaks.  This limits the percentage of FAME that can be contained in the fuel used by many existing diesel engines.

The process for producing FAME, while fairly simple chemically, involves the use of a water based catalyst (usually caustic soda) that must be mixed with the fat.  Since fats and water are not miscible, the reactor must be designed to form and then break an emulsion.   This makes large scale production somewhat capital intensive.  Also, the reaction produces glycerine as a by product that must be disposed of (or sold if you can find a market).

Another form of biodiesel can be produced using a conventional oil refining process (hydrotreating) to convert the fats to hydrocarbons.  This type of biodiesel is essentially the same as conventional petroleum based diesel fuels and can be used by any engine in any concentration.  The byproducts of this process are water and wax.