The most important ecological issue facing us today today's is the pollution caused by vehicles and transportation. This fact is in no doubt that engine gas emissions, especially from cars, trucks and other vehicles, cause severe damages to the environment as a whole and the human health as well. The replacement of conventional fossil fuels such as petrol and gas by biofuels is considered to be an excellent way to reduce pollution and carry on sustainable agriculture. The most widely used biofuels are biodiesel and ethanol. The use of biofuels as an alternative source is considered to be environmentally friendly by some. The process of production of biofuels on the other hand can cause pollution. The finiteness of fossil fuels such as diesel are major concerns for energy security and the need to steady the drastic climate change have led to growing interests in biofuels world over. Biofuels are thought to be a solution to the heavy reliance on foreign fossil fuels such as oil by many governments. Also they can play a part in lowering hazardous greenhouse gas emissions and helping in the development of rural areas. Still however government and general public vote in favor of biofuels has recently been on a low due to concerns about the environment as well as food security. There are reports that question the reasoning that biofuels considerably cut down on carbon emissions. Reserves of fossil fuels that are of course a nonrenewable resource (such as oil) will almost be depleted when about 80 to 85% of the fuel supply has been consumed. The remaining is thought to be very expensive and it is not feasible to extract it. Fossil fuels main issue is that its reserves will be almost depleted just within 35-85 years depending on how quickly it is consumed. At our current pace of consumption, fossil fuel reserves worldwide will last at least about 50 years. Undiscovered oil that is assumed to exist, will probably last another 20-40 years. The catch here is that instead of remaining at the same level as current global oil consumption is thought to increase by about 25% by the year 2010. This will quicken the process of depletion of global oil reserves.Biofuel Production:
The two most extensively used biofuels are biodiesel and ethanol. Generally biodiesel is made by using vegetable oils, animal fat, algae, and even in some cases recycled cooking greases. It can be used both as a diesel additive and in its pure form to fuel a vehicle. On the other hand ethanol is made by fermenting any bio-mass that is rich in carbohydrates. Commonly it is used as a fuel additive.The impacts of biofuels on the environment:
Majority of the biofuels are made from crops which include corn, soy bean and palm oil. These so called eco friendly alternative fuels could have a worse environmental effect as compared to the conventional fuels being used today. Some of the main negative impacts of biofuels are listed under the following headings. Comparing biofuels and other fossil fuels on the basis of environmental impact it is found that ecologically both forms of fuels has almost same harmful effects. There is not much significant difference between the two which could lead biofuels to have a better impact on the environment.
Higher food prices:
Although over the last few years production of Soya bean and corn (crops used for making biofuels) has increased considerably which generally looks like an environmentally friendly alternative to fossil fuels but environmentalists argue that this will lead to deforestation of rain forests. This competition for using crops as food as well as source of fuel will lead to high food prices.
Rain forest destruction:
Biofuels have dangerous side effects and steps need to be taken to make sure that land converted to grow biofuels does not damage the environment or cause social unrest.
Currently there are similar problems regarding palm oil which is also used in fossil fuels as rain forests are being destroyed in some areas and populations are forced to leave their homes for more palm oil plantation. As an example in Southeast Asia, oil palm cultivation leads to widespread deforestation that lessons biodiversity, downgrades significant ecological services, adversly effects climate, and puts workers in conditions that are sometimes analogous slavery.Green house emissions (bio versus fossil fuels):
When we are considering the greenhouse gas emissions on a whole it is therefore important to consider the whole production process and in what ways such production will affect the eco system. The effect of CO2 gas emission is dependent solely on the method from which it is produced and the feedstock used. Calculating thecarbon intensityof biofuels is a very complex and inaccurate process which is highly dependent on the assumptions that we make in the calculations. The emission factors of biofuels include:
- Emissions from fertilizers that are used in growing the feedstock
- Emissions from transportation of materials (like feedstock).
- Emissions from manufacturing biofuels by using feedstock.
- Emissions from change in the use of land of an area where the biofuel feedstock is produced..
Biofuel that is made from rapeseed could increase the green house gas emissions rather than decrease them as compared to fossil fuels. This is reported in a new study in the journal for 'Chemistry & Industry'. The researchers there have concluded that the gas emissions of the biofuels are almost equal to that of the conventional fossil fuels. They Have no effect on the betterment of the climate and only serve the purpose of energy security for the future.
Comparing emissions over full life cycles of greenhouse gases by fossil fuels and biofuels from the combustion in vehicles it was found that biodiesel manufactured from crops cultivated on farmland emits almost the same amount of harmful gas emissions as per kilometer driven as normal fossil fuels. If the land used to grow crops for manufacturing fossil fuels is used instead to grow environment friendly plants such as trees, the gas emissions by petroleum diesel would be only one third of the CO2 equivalent emissions exhibited by biofuels. Study made by Swiss government:
Recent studies conducted by a Swiss government study on 26 types of transport biofuels, Jorn P. W. Scharlemann and William F. Laurance say that arguments in favor of some large-scale biofuels often fail to fully account for the environmental costs of production, including destruction of forests, emissions of trace greenhouse gases, and air pollution. Fuels derived from "residual products, such as bio-waste or recycled cooking oil, as well as ethanol from grass or wood" may offer lower environmental costs, according to the authors.
"Biofuels are going to have a massive impact on nature and our economies, and we need to focus on the smartest biofuels," Laurance, a senior researcher at the Smithsonian Tropical Research Institute said "Some of the most important biofuels--notably those produced from corn, soy and palm oil--are generally bad for the environment. Biofuel from sugarcane is also harmful if tropical forests are being destroyed to produce it."Biofuels versus Food:
Concerns are increasing over the biofuels versus food competition for crops, says a Michigan State University professor. He says that ethanol from cellulose could make the debate useless. Bruce Dale (MSU chemical engineering and materials science professor) says that ethanol can be made from using cellulose containing materials such as farm waste. Then there is the fuel versus food debate. Converting lands for growing biofuel producing crops is a major concern. The demand for food is increasing day by day and requires more land to grow crops and feed for the livestock in order to meet the demands of the increasing population. Converting large pieces of land for biofuels will lead to a competition between food and fuel. This situation is very dangerous and if it goes on unchecked could lead to starvation. There seems to be a direct tradeoff and none of them can be compromised to increase the other as demand for both are increasing and both are important to our survival. 
"Our study suggests that farmers in Europe who are growing rapeseed for biodiesel might combat global warming in a more effective way, namely by converting those fields into forests and using conventional diesel for fuel," said Johnson. "It also suggests that rapeseed biodiesel does not deliver the global warming benefit over conventional diesel that is so often presumed by EU member states." Impact of biofuel producing crops on their environment:
Environmentalists are concerned that these crops could damage the environment because they have features such as fast growth and large water utilization. There is an increasing political and social pressure to work on these biofuels the government needs to carefully weigh the advantages of the biofuels to its cost to the environment. 
Carbon will be released when there is deforestation and also long term emissions from decaying dead roots. This creates a 'carbon debt 'so termed byJoseph Fargionof The Nature Conservancy and his colleagues. This decrease in hazardous emissions generated by using biofuels will help in paying back the carbon debt but their analysis suggests that in some cases it takes centuries. 
Livestock is fed corn and currently there is a high demand for meat therefore switching land for the production of biofuels is likely to pressure farmers all over the world to clear forests and additional lands to create land for growing crops which in turn will fill the void left by the missing corn. When we take into consideration the carbon released by this deforestation, biofuels produce nearly twice as much carbon as petrol and other fossil fuels.Increasing efficiency of Biofuels:
Biofuels are not a cure for climate change but they can play their part as long as governments and companies manage the social and environmental impacts thoroughly. Greater measure should be taken to increase efficiency and in turn reduce demand. There should also be greater measure taken to increase efficiency and to reduce demand. The fertilizer used for the growth of these crops is also hazardous. The energy that is released from the burning of ethanol is only slightly more (only 25 %) than the energy used to grow and process this fuel. This number has to be increased dramatically through research to improve efficiency which would lead to a positive impact on the environment. The graph below gives a net energy yield of biofuel sources.Conclusion:
Rising fuel prices coupled with concerns about carbon emissions are making biofuel production more cost competitive and attractive. Fossil fuels energy use poses environmental costs that are not shown in market prices. Does the biofuel provide benefits to society on a whole depends not only on whether it is cost competitive but also on its environmental costs and benefits as compared to its fossil fuel alternatives. There are global implications for the shift towards biofuels, and in this review paper, we have highlighted net positive GHG emissions, threats due to deforestation and biodiversity, increase in food prices and scarcity of water sources as the main hazardous impacts of biofuel use. On the other hand, we have also shown that the development and use of next generation biofuel feedstock's and production technologies may reduce some of the environmental and societal costs associated with biofuels. We conclude that certain types of biofuels do represent potential sources of alternative energy, but their use needs to be tempered with a comprehensive assessment of their environmental impacts. In recent years, there has been a policy driven and economically facilitated drive for biofuel production, and only now are the environmental costs of this becoming apparent. A careful evaluation of potential costs and benefits of the range of biofuel production processes is needed to shape more informed policy in the future. Nevertheless, we believe that together with increased energy conservation, efficiencies and technologies such as solar-, wind-, geothermal-, and hydro-electric power, biofuels should be included in a diverse portfolio of renewable energy sources in order to reduce our dependence on the planet's finite supply of fossil fuels and to insure a sustainable future for our species.
- Biofuels demand will increase, not decrease, world food supplies mongabay.com March 27, 2007 http://www.usingenglish.com/comprehension/42.html
- CITATION: J.P.W. Scharlemann and W.F. Laurance (2007). "How Green are Biofuels?" SCIENCE VOL 319 4 JANUARY 2008