The Chemistry of Biofuels

According to researchers at Lawrence Livermore National Laboratory and Sandia National Laboratory, the chemistry of biofuels is substantially more complex than the chemistry of petroleum. There are two major reasons for this enhanced complexity, which are explored here. In subsequent articles, we take a closer look at the properties of biofuels. The bottom line is that producing biofuels requires greater expertise in chemistry and an expertise in biology that is hardly considered when dealing with fossil fuels.

Variety

Petroleum is a rather simple substance because almost all of the molecules are hydrocarbons. Though come in varying lengths and some are gases, others are liquid, and still others are solids, the fact that they are all made of hydrogen and carbon means that they all behave in roughly the same way. The same is not true of biofuel.

Biofuels contain oxygen. By adding just that one atom, the complexity of these molecules begins to rise dramatically. Whereas the major difference between fossil fuels revolves around whether they have single or double bonds and how long they are, the differences between biofuels are far more complex. Because of the oxygen, biofuels can contain alcohols, esters, ethers, and acid groups. Each of these groups is a whole subset of organic chemistry and each has special reaction characteristics. Alcohols are really nothing like ester, which are not like acids at all. The net result of adding oxygen is a huge jump in complexity.

Biology and Synthesis

When dealing with fossil fuels, the processes are all chemical or physical. What is more, fossil fuels aren’t really produced so much as they are refined. Petroleum already contains gasoline, diesel, and other useful compounds. All industry really does is refine the petroleum in order to separate out the parts. It is true that they do other things, like cracking, to improve yield, but the basic process of getting fuel from petroleum is relatively straightforward.

The same is not true of biofuels. Before a biofuel can ever be used, the feedstock first has to be produced. This requires a complex understanding of chemistry and biology. In many cases, organisms are genetically modified to improve yield and to reduce nutrient and water requirements. Thus, one must have a thorough grasp of biology before even planting a biofuel crop. After that, biofuel is either refined from oil or produced by algae and harvested. In either case, complex chemistry is involved to get useful fuels out of biological molecules.