What is Bioethanol?
Bioethanol is used as a principal alternative for petrol, especially for road transport.
Bioethanol production from renewable resources is getting worldwide attention appreciation as its production is good for the country’s energy security and economy.
Ethanol of ethyl alcohol(C2H5OH) is a biodegradable colorless liquid that is low in toxicity & environmental pollution.
The best way to reduce pollution emission to the highest extent is by blending ethanol with gasoline. Ethanol blends are widely sold in many countries.
The most common blend is 10% ethanol and 90% petrol (E10). This blend is used in road transport. Vehicle engines require no modification to run E10, and also it will not affect the vehicle warranty.
Bioethanol production is mainly done through a sugar fermentation process. But, it can also be manufactured through the chemical process of reacting ethyl with steam.
Note: “The main sources of sugar required to produce ethanol come from fuel or energy crops.
These crops are grown specifically for energy use and include corn, maize, and wheat crops, waste straw, willow and trees, sawdust, reed canary grass, cord grasses, Jerusalem artichoke, miscanthus, and sorghum plants.”
Interested in biofuel industry? Check: biodiesel pump dealership franchise details for in-demand dealership model.
Benefits of Bioethanol
There are numerous advantages of Bioethanol over conventional fuels.
Bioethanol production includes three processes
Biomass waste consists of a mixture of carbohydrate polymers from the plant cell walls known as cellulose, hemicellulose, and lignin.
The biomass is pre-treated with acids and enzymes to produce sugars from the biomass. After that, the cellulose and hemicellulose parts are broken down by enzymes/acids into sucrose sugar, fermented into ethanol.
For ethanol production plant boilers, lignin which is present in biomass, is also used as biofuel.
There are three basic methods to extract sugars from biomass. These are
- Concentrated Acid Hydrolysis
- Dilute Acid Hydrolysis
- Enzymatic Hydrolysis
Concentrated Acid Hydrolysis Process
The process works by adding 70-75% of sulphuric acid to the dried biomass having only 10% moisture content. The acid is added to the biomass, and the temperature is maintained at 50C.
After that, water is added to dilute the acid tp 20-30%, and then the mixture is heated again at 100C for 1 hour. The resulting gel extracted from the mixture is then compressed to release acid and sugar mixture.
Finally, a chromatographic column is used to separate the acid and sugar mixture.
Dilute Acid Hydrolysis
It is one of the oldest and easiest processes to extract ethanol from biomass. Dilute acid is used to hydrolyze the biomass.
Its first stage uses 0.7% sulphuric acid to hydrolyze the hemicellulose(present in biomass). The second stage yields a more resistant cellulose segment. It uses 0.4% sulphuric acid at 215C.
In the last, liquid hydrolates are neutralized and recovered from the whole process.
In this process, enzymes are used to break down the biomass instead of using acid to hydrolyze the biomass into sucrose. This process is not well worth because it is costly and is still in its early stages of development.
Sugar Fermentation Process
Mostly, Sugar Fermentation Process is practiced to produce ethanol from biomass.
That’s the reason we will discuss only about this; rest all the processes are not of that much importance.
The process includes a hydrolysis process that breaks down the cellulostic part of biomass into the sugar solution. Yeast is added to the solution, which is then heated. The added yeast consists of an enzyme called invertase, which acts as a catalyst. It benefits of convert sucrose sugars into glucose and fructose.
The chemical reaction is shown below:
The final product obtained then reacts with another enzyme called zymase. This enzyme is also present in yeast, and it helps to produce ethanol and carbon dioxide.
The chemical reaction is shown below:
The fermentation process takes around three days to present the final output. The whole process is carried at a temperature of between 250C and 300C.