Environmental Engineering Reference
In-Depth Information
weather, high oil prices for oil, increased demand for meat and dairy products in the
some Asian countries and the push in the West to use biofuels derived from grain,
especially maize, to reduce oil consumption. A knock on effect on the increase in the
price of other crops (not for fuel application) may be envisaged by example in the
production of first generation bioethanol, which uses carbohydrates such as starch
and sugar from maize and sugarcane, which results in better prices for these crops.
Thus farmers may switch production to these as opposed to the production of others
crops, resulting in a price increase.
1.3 Destruction of the Rainforest
The production of biodiesel relies on the use of crops such as soya, rape, and palm
which are pressed releasing oils (and rest presscake) which are transesterified yield-
ing fatty acid mono alkyl esters (usually methyl) and glycerol and the topic of
growth of these. For example the growth of soya in South America, and in par-
ticular in Brazil, has raised discussions about the destruction of the rainforest for
soya production. The production of sugarcane in the Amazon is less suitable due
to the wetter climate, however due to expansion of production of sugarcane, land
used for soya production is therefore reduced leading to supplementary production
of soya in the Amazon.
1.4 Greenhouse Gases
For the conversion of non-agricultural land such as grasslands to production of
maize (for bioethanol) would first require removing the plants/grasses and convert-
ing it to agricultural land. This process leads to an overall increase in CO 2 emissions
[3]. The effect of using fertilisers for cultivation should also not be ignored. Here the
greenhouse gas N 2 O is generated. For cultivation of forest areas the story is simi-
lar, as large amounts of CO 2 are formed as the organic material in soil (humus)
is decomposed by microorganisms, taking many years of using the biofuel pro-
duced on that site to redress the CO 2 balance (paying back the carbon debt) [4].
However biofuels made from waste biomass, for example, has little or no carbon
debt.
As well as the conversion of land use generating greenhouse gases, production
of the biofuel itself should be considered. In the case of the distillation process of
bioethanol, heating using coal is often used.
Therefore when considering the approach of converting biomass to fuel, smart
strategies as to obtaining biomass that does not negatively interfere with food
production and result in unfavourable land changes as well as having a good green-
house gas balance with respect to obtaining the biomass and its conversion are
of importance. As well as this one should not forget the potential for small scale
farmers in developing countries to obtain benefits from the crops that they are
cultivating.
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