The liquid fuels that can be obtained from biomass like plant matter or by the waste that living creatures produce, such as manure is known as Biofuels. They are mostly used to help meet transportation fuel needs.
Types of Biofuels
The two most common types of biofuels in use today are ethanol and biodiesel.
Any biomass which is high in carbohydrates can be fermented to produce Ethanol. Today, ethanol is made from starches and sugars. Ethanol can also be produced by a process called Gasification, where high temperatures and a low-oxygen environment is used to convert biomass into synthesis gas. This synthesis gas also known as syngas, can then be chemically converted into ethanol and other fuels. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. It is widely used in the USA and in Brazil.
is obtained by mixing alcohol which is usually methanol with vegetable oil, animal fat, or recycled cooking oil. Chemically, it consists mostly of fatty acid methyl esters. Pure biodiesel (B100) is the lowest emission diesel fuel. Biodiesel can be used in any diesel engine when mixed with mineral diesel. It is also used as an additive (typically 20%) to reduce vehicle emissions.
Examples include wood, sawdust, grass trimmings, domestic refuse, charcoal, agricultural waste, non-food energy crops, and dried manure. One of the advantages of solid biomass fuel is that it is often a by-product or residue of other processes, such as farming, animal husbandry and forestry. Hence, it is an efficient means of utilising something that is waste & converting it into something very useful.
Then there are Second generation biofuels. These are advanced biofuels produced from sustainable feedstock. Many second generation biofuels are under development such as Cellulosic ethanol, Algae fuel, biohydrogen, biomethanol, biohydrogen diesel, mixed alcohols and wood diesel. This is posing a challenge to the mankind as more land & resources would be required to produce feedstock for biofuels rather than getting utilized for food production.
Hence research work is going on to develop biofuel crops that would require less land and use fewer resources. For example algae is one such source for biofuels that could utilize unprofitable land and waste water from different industries, because it can be grown in waste water. Also algae do not affect the human food chain.
Pros of Biofuels
- Renewable – Biofuels are produced from plants and other organic material, so it can be replenished constantly. This is in contrast to the fossil fuels, which are constantly in the process of being depleted.
- Clean – Biofuels are environment-friendly. They are much efficient & cleaner than fossil fuels, producing less air pollution and using materials that would otherwise be considered as waste products. Biofuels cause much less greenhouse gas emissions in comparison to the conventional types of transport fuels.
- Inexpensive – They can be made easily by using local materials. Biofuels are very cheap to afford. They are the cheapest types of fuels available in the world.
- Flexible – can be easily mixed with other fuels.
- Additives – Biofuels like ethanol and biodiesel are better for car engines than fossil fuels. Even if not being used as the main fuel source, they can be used as additives to improve performance.
- Carbon neutral – the amount of carbon dioxide created by the burning of biofuels is equal to the CO2 absorption capacity of the plants. Hence, no extra CO2 remains in the atmosphere.
Cons of Biofuels
- Food vs. Biofuels – with the increased use of biofuels there will be an urge to grow more of the crops meant for biofuel production instead of food crops. A reduced food production can increase the price which may lead to inflation.
- Loss of habitat – More land would be required to be cultivated for Biofuel production. This is already considered a major problem, as it may result in a loss of habitat for various species of plants and animals.
- Harmful Nitrous oxide production – Although there is not enough carbon dioxide emission that would cause the greenhouse effect, yet the burning of materials to produce biofuels emits enough nitrous oxide to create a greenhouse effect.
- Limitations in its use in vehicles – Some kinds of biofuels require modifications to vehicle engines and they are still being used as additives rather than a fossil fuel replacement.
- Ignorance – Biofuels are not widely available and not many people are aware about it.
Biofuels are still in a nascent stage & needs lot of research & development to make it more popular. Given some of its disadvantages, one of its biggest advantage is that there are chance of it being used as a replacement of fossil fuel which is so fast depleting & is not renewable.