How to Master the ielts

70
D
To judge whether or not biofuels are genuinely a greener alternative to fossil fuels 
it is necessary to scrutinize the manufacturing steps. Whilst in theory, the carbon 
released by biofuels is equivalent to that removed from the atmosphere by the
growing plants this does not reflect the true energy picture. Substantial amounts
of nitrogen­based fertilizers are added to the soil to increase crop production. The 
process of manufacturing fertilizers consumes large amounts of energy in a process 
that burns natural gas and releases carbon­dioxide. What’s more, when fertilizers
are added to the land the soil releases nitrogen oxides into the atmosphere. As an 
agent of global warming, nitrous oxide is about 300 times more potent than carbon­
dioxide, and surplus nitrates can leach into nearby rivers and streams where they
kill the fish. The ethanol industry generates additional carbon­dioxide because many 
of its manufacturing plants use coal­fired boilers, and fossil fuels are also consumed 
by the vehicles that transport materials to and from manufacturing sites. Whilst
the transportation of petroleum­based fuels also burns fossil fuels, biofuels are
supposed to offer a greener alternative to the fuels they intend to replace.
E
Biofuels may not be a panacea for global warning but they can play a part in 
a sustainable energy programme. To reinforce their green credentials, energy crops 
should not be planted on land that was being used to produce food. New technologies 
can produce ethanol from the inedible parts of plants, or from grasses grown on 
wasteland that is unsuitable for food. Genetically modified plants may be the answer 
to increasing biofuel crop yields without the need for further land grab. Plant strains 
can be developed that require little in the way of fertilizers or irrigation. Biodiesel
consumption may, in the future, extend beyond transportation to include heating oils 
for domestic boilers. Developing countries that grow biofuels should be allowed to 
benefit from the premium prices that fuel crops command, enabling farmers and 
their communities to reap economic and social benefits. Whatever the advantages 
and disadvantages of fuel crops it is clear that fossil fuels are a limited resource
and cannot remain the mainstay of our economies indefinitely.

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TEST 3