Agriculture Reference
In-Depth Information
The use of E10 achieves a 25% or greater reduction in carbon monoxide (CO) than petrol
fuel. Meanwhile ethanol blended petrol emits higher evaporative hydrocarbons (HC) and
others volatile organic compounds (VOCs) than petrol. This is primary due to increase of
higher vapour pressure of ethanol mixture.
Nevertheless, raising the ethanol concentrations further does not lead to significant
further increases. Impacts of ethanol on nitrogen oxides (NOx) are generally minor, and can
either be increased or decreased, depending on conditions [18]. Composition of gasoline and
ethanol increase emission of most toxic air pollutants like benzene, 1,3-butadiene, toluene and
xylene. This is consequence of dilution effect of ethanol which substitutes some part of
gasoline, which emits toxic air pollutants [19].
Nevertheless it must be considered that the wider environmental impacts of biofuels are
as variable as the potential GHG savings and depend very much on location and production
method. A case by case assessment might therefore be required [38]. With the exception of a
few studies that report associated increase in GHG emissions, most studies find a significant
reduction in both global warming emissions from both ethanol relative to conventional
transport fuels [42]. There are several equations to establish the overall conversion efficiency
of technologies for the conversion of solar energy, there should be a correction for the
cumulative energy demand associated with the biofuel life cycle and the life cycle of physical
conversion technologies [26].
For instance, if the lower heating value of fossil fuel inputs amounts to 20% of the lower
heating value of a biofuel, the solar energy conversion efficiency will be corrected by this
percentage. Assessments of the environmental impact of biofuels often significantly differ in
methodological choices and consequently in their results [68].
The most common definition of sustainability was given by the World Commission on
Environment and Development in 1987. It means to satisfy our present needs without
compromising the future generations‟ ability to meet their own needs. The definition implies
the balance of three components, stated in the Declaration of Rio on Environment and
Development in 1992; environmental protection, economic growth and social development
[69]. Consequently, the sustainable production of bio energy is defined as the production of
biomass based fuels for transportation, heat and electricity generation that allows an
economic growth preserving the natural environmental and promoting a well-balanced social
development. Due to the exponential growth in biofuels production, significant concerns have
been raised about the sustainability of the production strategy.
Certain risks to the economic growth, the preservation of natural environment and the
social development have been identified. The economic performance of the biofuel
production strategy depends on oil prices.
Due to the instability and fluctuation of the oil markets, the sustainable economic growth
of the biofuel production system is not always guaranteed. Moreover, the scale economy
plays an important role in achieving the economic viability. The life cycle emission,
deforestation for feedstock production, the degradation of soils, and consumption of water
and loss of biodiversity may impact more or less severely the natural environment.
Finally, the food availability, the working conditions, and the distribution of benefits
introduce risks of imbalances in the social development.
Hence, a consistent framework and robust methodology are needed to verify that biofuels
are produced in a sustainable way [68].
