What are bio fuels?

As the name suggests bio fuels are fuels that are derived from biological processes by reducing inorganic carbon to organic compounds by living organisms (which in scientific terms is called carbon fixation). Bio fuels are usually obtained from renewable biological resources like plant biomass, and treated municipal and industrial waste. Hence, they differ from fossil fuels as they are derived from easily renewable sources. A fuel, produced to from a biological process, is called a bio fuel only if it contains over 80 percent renewable materials.

What are the different forms of bio fuels?

Bio fuels can be obtained in all three forms-solid (biomass), liquid (liquid fuels) and gaseous state (biogases). There are many types of bio fuels like- bio ethanol, biodiesel, biogas, solid biomass, algae fuel, bio ethers and many others are being developed across the world every day.

The most famous and most commonly used bio fuel today is bio ethanol, which has specifically taken over the fuel needs in Brazil due to abundance of sugarcane. Bio ethanol is produced from the process of fermentation of sugars, starch and cellulose derived from sugarcane, molasses, wheat and corn. Apart from bio ethanol lesser used fuels which come under same class are bio propanol and bio butanol or bio gasoline due to similar properties as petrol.

Another major bio fuel which is gaining tremendous popularity in Europe is biodiesel, which is slowly phasing out diesel in many parts of the world due to its low emission (B100 which is pure biodiesel is the lowest emission diesel). Biodiesel is produced from oils and fats obtained from animal fat and oils obtained from various plants like soy, mustard, palm, jatropha, rapeseed and many more. Another type of diesel which is being researched upon is green diesel which although derived from same sources is biologically different from biodiesel due to different process of production.

                                                    Figure 1 : Biofuel Production in the United States 1990-2008.

what are bio fuels

Sources: Renewable Fuels Association, Historic U.S. Fuel Ethanol Production, accessed May 10, 2009.  National Biodiesel Board, Production Capacity, 2008.

Another very common bio fuels which doesn’t need much introduction is biogas which is widely used in rural areas by families which own cattle stock. Biogas consists of methane which is produced from biodegradable waste which is digested anaerobically (lack of oxygen) by anaerobes (bacterias that don’t need oxygen to function). Another form of gaseous bio fuel is syngas which is produced by partial combustion of biomass, which is a mixture of carbon monoxide, hydrogen and other hydrocarbons.

Solid biomass is the oldest and most widely used type of bio fuel in rural areas of many under-developed and developing nations. Firewood, dung-cakes (which are very common in rural India too), agricultural waste and other solid biological waste come under this class of bio fuel. This type of bio fuel, since being the oldest and crudest, is the most polluting class of bio fuel.

Apart from these bio fuels which have been researched upon since many years, a new generation of bio fuels are being developed which are a lot cleaner than their predecessors. The most common ones amongst them are algae fuel, cellulose ethanol, bio hydrogen and bio methanol.

biofuel pathways

How are bio fuels being used and there advantages?

As mentioned earlier bio fuels have gained popularity in many places around the globe, most notably bio ethanol in Brazil and biodiesel in Europe. Ethanol’s biggest use is as a replacement for petrol in petrol engines or it can be used by mixing it with petrol (most of today’s petrol engines can run with up to 10-15 percent of ethanol mixed with petrol). A major advantage of using ethanol rather than just plain petrol is ethanol’s higher octane rating, which is measurement of thermal efficiency. Similar to ethanol, biodiesel can be used in any diesel engine by mixing it with conventional diesel.


In India biodiesel is produced locally and used to run large and slow engines in trains, heavy duty trucks and tractors. Due to its efficiency in Indian conditions and cheapness it is slowly beating two of its biggest competitors-conventional diesel and the illegally used, kerosene. The southern railways have been a flag bearer for this bio fuel, and amongst all states, Karnataka is leading the green brigade in this field as they use biodiesel blends to run the KSRTC (Karnataka State Road Transport Corporation) buses. To encourage and organize the industry a Biodiesel Association of India (http://www.bdai.org.in/) has been formed to ensure increase in plantations for feedstock supplies. Apart from India, these bio fuels for vehicles have gained so much popularity and trust that in many areas they are cheaper than their less ‘green’ ancestors. Another bio fuel which has a tremendously large field of proven application is biogas. Biogas can be used for wide variety of applications like electricity generation in sewage treatment plants, to being an alternative for CNG (compressed natural gas) in vehicles. Sweden has pioneered a biogas run train service which has been running successfully for almost half a decade. A new revolutionary and futuristic use that’s being worked upon by Philips is developing bioluminescent lamps powered by biological reaction of methane in biogas with bacteria. Apart from all these complicated uses one forgets to take notice of biogas’s most simple and effective uses-cooking and heating!


What are the limitations of bio fuels?

The biggest reason why bio fuels haven’t been able to completely replace their fossil origin ancestors is due to cost of production and developing new technology to ensure the process is cheaper than existing technology. This is a major concern especially for algae fuels as being in its youth stage production of fuel from algae’s requires lots of research and capital. Since investors expect good returns and huge profits, a developing fuel source like algae are facing tough competition from already established conventional crops and other renewable energy sources like solar and wind. Apart from the monetary point of view many researches are being conducted by various groups to show that bio fuels are not greener than fossil fuels, whereas many earlier researches have earlier proven that bio fuels emit lesser harmful gases than the non-renewable fossil fuels.

What is there for the future?

The future of bio fuel is believed to be in a new generation of fuels called algae fuels which as the name suggests uses algae as its source for generation of fuel. Algae has been researched upon to produce biodiesel, ethanol, biogas and due to current increase in oil prices several airline companies have started experimenting with algae to produce jet engine fuel.  The major advantage of using algae fuel is that it is highly environment friendly as the carbon dioxide produced by the fuels are taken up in a huge proportion by the algae itself and algae’s produce almost 400 times more fuel compared to conventional crops like rapeseed, soy, corn and palm. Another advantage of algae over conventional crops is the rapid rate of growth which is more than 20 times faster. All these reasons are making algae a huge favourite to produce to future batches of bio fuels in a cheaper and more environment friendly way.

The future of bio fuels is looking strong now due to the huge number of researches being conducted to produce next generation of bio fuels from previously untapped sources like algae and jatropha curcas (or better known in India as ratanjot). Another very innovative and exciting research was done, by a group from Russian Academy of Sciences, in producing bio fuel from fungi. This new source will be a major field of research in the future as many such fungi have been discovered which can be used as an economically feasible and reliable source for bio fuels for our future generations. The aim of all researches in the field of bio fuel is to increase its yield and to try and produce as green and efficient fuel as possible without burdening the pockets of the investors or consumers.

Bio fuels will always be a field where every day with advanced research, new and highly unconventional sources to produce fuel will be discovered and scrutinized. No matter how much research is done to show the ineffectiveness of bio fuels compared to conventional fossil fuels, bio fuels will outlive the fossil fuels as it’s a renewable source of energy. It’s time the world started moving towards renewable sources of energy and engineer new technology to support this move. Maybe most of the bio fuels are not as economically viable compared to fossil fuels but they are definitely more sustainable and one which will last for many more generations satisfying everyone’s fuel needs. Although other sources of renewable energy, like solar and wind, are giving huge competition to bio fuels, for future domination once the reign of fossil fuels ends, bio fuels have an advantage as still our heavy machineries are run by diesel and petrol. It will take many more generations to ensure a completely green, feasible and easily renewable source of energy and to further develop technology to suit it, but till that happens bio fuels will be the next flag bearer amongst sources of energy once fossil fuels get depleted. Bio fuels have existed in crude form since ages ago and will keep developing into more and more sophisticated forms as research continues in the future. Bio fuels have made a special relation with humans, which cannot be broken which makes bio fuel one of the most important gift for us from nature.

NREL, EIA, Europa