What is bioethanol?
Bioethanol is a fuel which can be used as a substitute for petrol (or sometimes called “gas” in the USA) which is produced via a fermentation process of renewable crop and plant matter. Bioethanol is the most popular biofuel in use in the world today and it can be used in most car engines as a gasoline substitute (or specifically with a mix of ethanol and gasoline).
The two largest markets for bioethanol are Brazil and the USA, with both markets covering up to 70% of the total world bioethanol usage.
In the chemical sense, bioethanol and ethanol is exactly the same compound and have the chemical formula C2H6O or C2H5OH.
How is bioethanol made?
Bioethanol is a form of grain alcohol which is the same type of alcohol that is found in alcoholic drinks, but bioethanol is distilled from biomass materials.
There are different ways that bioethanol can be produced from biomass. It can be produced by the hydrolysis and the sugar fermentation methods. It is necessary to produce sugars from the biomass to aid fermentation and this is done by treating the biomass with acids and enzymes to open up the plant structure of the biomass. The cellulose is then broken down by the enzymes or acids into sucrose sugar which is then fermented into bioethanol. The main ways of extracting the sugars from the biomass material are the dilute acid hydrolysis method, using concentrated acid hydrolysis or the enzymatic hydrolysis technique.
The actual fermentation into bioethanol takes about three days to complete and it is completed at a temperature of around 275C.
Uses of bioethanol?
The main use of bioethanol is in the form of a fuel alternative to that of petrol. Usually it is used as a low percentage blend with traditional petrol such as a 5% or 10% blend oil ethanol with the remainder being standard petrol. There are already a number of automobile manufacturers that are building models that use bioethanol blends.
Bioethanol is being produced in great quantities with 28 billion gallons being produced globally in 2010 and the European Commission stating in a recent report that there is a commitment to ensure that bioethanol makes up 10% of all transport fuel used in Europe.
Advantages of bioethanol
Bioethanol can be considered as a renewable type of fuel because it is derived from biomass fermentation processes (biomass is a renewable source).
The use of bioethanol is generally CO2 neutral. The reason for this is that the CO2 that is absorbed by the source biomass crop which is used for bioethanol production is roughly the same as the output of CO2 from the combustion of the bioethanol fuel in transport vehicles, etc.
Some car manufacturers are developing cars that are capable of running on an E85 basis. This means the blend of fuel that the cars use is 85% ethanol and 15% gasoline. These types of Fuel-Flex Vehicles (FFVs) are currently being developed by Ford, Saab and Volvo.
There are a wide variety of plants/crops that can be used for the production of bioethanol – the main characteristics needed are that the crops contain sugar and starch. This is the reason why sugar cane is a particularly widespread crop which is used in the production of the biofuel.
As technology increases it is likely that the fuel mix required for engines will increase leading to cleaner emissions or it will even lead to 100% ethanol car engines.
Bioethanol production can take place in any location where the required crops can be grown. This means we are not dependent on dwindling oil reserves that are expensive and subject to wildly fluctuating prices.
Disadvantages of bioethanol
The energy content of bioethanol is typically one third lower than the equivalent amount of petrol.
Transport of bioethanol is problematic because it is hygroscopic. This means is absorbs water from the air and as such it is only currently transported over ground by vehicle or train.
To create bioethanol we need suitable crops or biomass that contains the required pre-requisites for fermentation. If we are producing these crops in massive volumes largely for the production of fuel, we are using land that would otherwise have been used for food crops. This could result in a food shortage if mismanaged by crop producers.
Cars running on ethanol need modification and in the case of E85 cars they are a new breed of cars called Fuel Flex Vehicles, so anyone wanting to run their care on E85 will need to buy a new FFV car.