Ethanol is an alcohol that is used for preservatives, disinfectant, and can be a source of renewable energy. It’s also an alcohol that can be found in alcoholic beverages. Ethanol also known as ethyl alcohol (C2H5OH) is a colorless liquid. Some of its characteristics include its ability to decompose (biodegradable), low in toxicity, and causes little environmental pollution if leaked. In connection, bioethanol is widely used for petrol substitute for road transport vehicles. Bioethanol fuel is mainly produced by the sugar fermentation process, although it can also be manufactured by the chemical process of reacting ethylene with steam. 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 popular trees, sawdust, reed canary grass, cord grasses, jerusalem artichoke, myscanthus and sorghum plants. There is also ongoing research and development into the use of municipal solid wastes to produce ethanol fuel. When ethanol burns, it produces carbon and water. By blending ethanol with gasoline we can also oxygenate the fuel mixture so it burns more completely and reduces polluting emissions. Ethanol fuel blends are widely sold in the United States. The most common blend is 10% ethanol and 90% petrol (E10). Vehicle engines require no modifications to run on E10 and vehicle warranties are unaffected also. Only flexible fuel vehicles can run on up to 85% ethanol and 15% petrol blends (E85). Ethanol can be produced from biomass by the hydrolysis and sugar fermentation processes. Biomass wastes contain a complex mixture of carbohydrate polymers from the plant cell walls known as cellulose, hemi cellulose and lignin. In order to produce sugars from the biomass, the biomass is pre-treated with acids or enzymes in order to reduce the size of the feedstock and to open up the plant structure. The cellulose and the hemi cellulose portions are broken down (hydrolysed) by enzymes or dilute acids into sucrose sugar that is then fermented into ethanol. The lignin which is also present in the biomass is normally used as a fuel for the ethanol production plants boilers. There are three principle methods of extracting sugars from biomass. These are concentrated acid hydrolysis, dilute acid hydrolysis and enzymatic hydrolysis.
Bioethanol has a number of advantages over conventional fuels. It comes from a renewable resource i.e. crops and not from a finite resource and the crops it derives from can grow well in the UK (like cereals, sugar beet and maize). Another benefit over fossil fuels is the greenhouse gas emissions. The road transport network accounts for 22% (www.foodfen.org.uk) of all greenhouse gas emissions and through the use of bioethanol, some of these emissions will be reduced as the fuel crops absorb the CO2 they emit through growing. Also, blending bioethanol with petrol will help extend the life of the UK’s diminishing oil supplies and ensure greater fuel security, avoiding heavy reliance on oil producing nations. By encouraging bioethanol’s use, the rural economy would also receive a boost from growing the necessary crops. Bioethanol is also biodegradable and far less toxic that fossil fuels. In addition, by using bioethanol in older engines can help reduce the amount of carbon monoxide produced by the vehicle thus improving air quality. Another advantage of bioethanol is the ease with which it can be easily integrated into the existing road transport fuel system. In quantities up to 5%, bioethanol can be blended with conventional fuel without the need of engine modifications. Bioethanol is produced using familiar methods, such as fermentation, and it can be distributed using the same petrol forecourts and transportation systems as before. However, ethanol has a lower energy density than that of gasoline, meaning more ethanol - in terms of volume and mass - needs to be combusted to produce the same amount of energy. In fact, energy per unit volume of ethanol is 34% lower than that of gasoline,[5] therefore 1.5 gallons of ethanol contains approximately the same amount of energy as one gallon of gasoline does.
An additional advantage of ethanol is that it has a higher octane rating than gasoline, allowing engine designs with higher compression ratios, meaning ethanol driven engines can be designed to have higher thermal efficiency. Although the energy contained per gallon of ethanol is less than gasoline, as the energy within the fuels is converted to the mechanical movements of the vehicle, the ethanol engine will waste less energy as compared to that of gasoline. An ethanol-only engine can be designed for better theoretical power output and higher thermal efficiency, meaning an ethanol powered car will have better performance and waste less energy. Also, if bioethanol is used, the carbon dioxide released when ethanol is burned is balanced by the carbon dioxide captured when the crops are grown to make ethanol. This differs from petroleum, which is made from plants that grew millions of years ago. On a life cycle analysis basis, corn-based bioethanol production and use reduces greenhouse gas emissions (GHGs) by up to 52% compared to gasoline production and use. Bioethanol use could reduce GHGs by as much as 86%.
The world never stops advancing by means of upgrading various machineries and innovating what we currently use today. In connection, we have to use this advancement in creating something that will not just benefit humans but also the world that we live in.