Comparison of Bioethanol and Biodiesel
The two most widely used types of biofuels are ethanol and biodiesel.
Ethanol is an alcohol fuel derived from sugarcane, wheat, corn and biomass, thus including wasted cooking oil. It can be blended with conventional petroleum diesel to improve its octane level resulting in reduced greenhouse gas emissions
Biodiesel is made from natural oils such as animal fats or vegetable oils.
Bioethanol | Biodiesel | |
Process | Dry-mill method: yeast, sugars and starch are fermented. From starch, it is fermented into sugar, afterwards it is fermented again into alcohol. | Transesterification: methyl esters and glycerin which are not good for engines, are left behind. |
Environmental Benefit | Both reduce greenhouse gas emissions as biofuels are primarily derived from crops which absorb carbon dioxide. | |
Compatibility | ethanol has to be blended with fossil fuel like gasoline, hence only compatible with selected gasoline powered automobiles. | Able to run in any diesel generated engines |
Costs | Cheaper | More expensive |
Gallons per acre | 420 gallons of ethanol can be generated per acre | 60 gallons of biodiesel per acre soybeans cost of soybean oil would significantly increase if biodiesel production is increased as well. |
Energy | provides 93% more net energy per gallon | produces only 25% more net energy. |
Greenhouse-gas Emissions (GHG) | 12% less greenhouse gas emission than the production and combustion of regular diesel | 41% less compared to conventional gasoline. |
