In this era of global warming and price hike it was necessary to find the best choice of fuel. The conventional method known to man was to use gasoline. But again a question arose which type of raw material need to be used for obtaining gasoline. Gasoline was usually made from coal or crude oil. But as the cost of coal and crude oil began to rise, it became indispensable to find alternative sources of fuel or a mix of these two raw materials. The cost of using these two raw materials were almost the same but it was lower for oil derived gasoline. This led to the wide spread use of oil derived gasoline.
Later on several studies were made to find the best possible mixture of fuels because relying on one form of fuel would decrease its availability in nature. So 80% oil derived gasoline and 20% coal derived gasoline was used. But all these fuel production from raw materials had a wide impact on the atmosphere. So scientists tried to develop fuels from bio-ethanol which was in turn obtained from sugarbeet and other municipal wastes. Although it was more expensive than oil derived gasoline it helped a lot to reduce the Co2 emissions to a great extent and proved to be the best possible way. To help get the fuel the characteristics of gasoline, they also used 30% gasoline along with bio-ethanol. This came to be known as E-70 which was both cost effective and also environmental friendly.
The results were indicating a proportional change in the cost of gasoline with respect to its raw materials, whether it's crude oil or coal. The price of gasoline was the highest in 2009, while it was more or less the same in 2007 and 2009. The price of coal was much low in the year 2007 and hence the price of coal derived gasoline was the lowest in that year. In 2008 and 2009, as the coal prices were much higher compared to crude oil, it was found better to use a mixture of 80% oil derived gasoline and 20% coal derived gasoline.
It was then, that the E-70 came in to use. It consisted of 70% bio-ethanol and 30% gasoline. The production of bio-ethanol solely depended on sugarbeet yield and the cost. The price was the least and yield was the highest in 2008. The cost increased by 7$/tonne for the year 2009 but the yield was pretty good. But that also proved futile as the net cost of production was still high and the land area required was not enough to produce ethanol to substitute gasoline. So taking into account all these minute details it was better to derive gasoline from crude oil as the cost was the least in this case.
The CO2 emission depends on the raw material used for production of gasoline. The product of the carbon content of the fuel and the ratio of molecular weight of carbon dioxide to molecular weight of carbon.(i.e. carbon content of fuel * 44/12) shall yield the amount of CO2 emission.
The values would be different for coal and crude oil. For coal, it would be 0.37 kgCO2 / kWh and for crude oil it will be 0.26 kgCO2 / kWh. So from the environmental point of view, it would always be better to use coal instead of crude oil as the raw material for gasoline. But instead, if E-70 was used, the amount of CO2 emissions will be further reduced because it contains more of bio-ethanol derived from sugarbeet. As the plants are requiring CO2 to grow, the amount of produced during conversion of biomass into bio-fuel will be nullified. Furthermore it will reduce the global warming to large extent.
The main draw backs when using coal and crude oil would be the difficulty in recycling it. There will not be much left over to recycle except the fly ash obtained from coal which could be used with concrete in buildings. Even here, E-70 fuels were better because bio-ethanol was made up of trees, grass, municipal solid waste etc. So it was always easier to be recycled and had better applications compared to the other raw materials.
- Environmental emission of carbon dioxide CO2 when combustion fuels like coal, oil, natural gas, LPG and bio energy http://www.engineeringtoolbox.com/co2-emission-fuels-d_1085.html
- Bioethanol-the Climate-Cool Fuel, Biofuels, DOE/GO-10097-515, November 1997, http://www.nrel.gov/docs/legosti/fy98/23761.pdf