subject: The Manufacture Of Ethanol [print this page] Actually, although most of us had never heard of ethanol before the crisis in oil and gasoline prices in recent years, humans have been making it for thousands of years. Why is that? Because it's so easy to produce. It can be made from any vegetable source that has enough sugar or ingredients that can be converted into sugar (starch and cellulose, for instance). Sugar cane and sugar beets come to mind. Corn also has starch that can be turned into sugar, but it takes more processing to convert the starch.
Here is the simplest possible description of the process:
1) Grind up kernels of a grain such as corn or wheat finely to expose the starch.
2) Mix the resulting mass with water.
3) Cook briefly and add enzymes that will change the starch to sugar. This process is called hydrolysis.
4) Add yeast. This will bring on the fermentation necessary to produce ethanol.
5) Distill it all to separate the ethanol from everything else.
That's it! Many websites are offering recipes for producing ethanol at home, which can be done. However, it turns out to be a lot of work with not a lot of production and is not cost-effective.
This is a field where there is a lot of commercial research activity right now, and a new process is underway to make ethanol not from the grains themselves but from cellulose that can come from less costly sources. It's more difficult to do this. The processes for this production are much more complex because there are pretreatment and hydrolysis steps to use acid and enzymes before fermentation can occur.
It's microscopic organisms called yeast that account for fermentation. We know yeast best as an ingredient in breadthe one that makes the bread rise. This is caused by carbon dioxide gas. These organisms are anaerobic in that they can live and eat without oxygen. Yeast eats sugar just as we do but it can't absorb all the energy in the sugar. While it is partially absorbing the energy and digesting the sugar, a conversion of the sugar into ethanol and carbon dioxide gas takes place.
So why not just make ethanol from the sugar in your pantry? It would take so much sugar that it would take a very large pantry! Brazil's, which has been using ethanol for fuel for decades, is made from sugar because that country grows a lot of sugar cane.
Commercial production makes ethanol without nature's help. It uses a byproduct of gasoline production and converts it into ethanol; however, a lot of it is still being made with yeast. Corn, more plentiful in this country than sugar cane, doesn't have as much sugar and more complex means are necessary to turn it into ethanol.
