Practise evaluating alternative fuels and transport choices using renewability, CO2 emissions and climate-change arguments.
Many cars use fuels containing ethanol as well as hydrocarbons. The E numbers of these fuels show the percentage by volume of ethanol in the fuel. For example, an E5 fuel contains 5\% ethanol and 95\% hydrocarbons by volume.
Many countries are gradually replacing E5 fuels with E10 fuels.
Explain how this change might result in a more sustainable fuel.
An answer that makes reference to three of the following points:
- (increased amount of) ethanol used could be bioethanol / ethanol sourced from plants
(1)
- from fermentation (of sugars / glucose using yeast)
(1)
- reducing CO_2 emissions (overall) / (some) CO_2 released in combustion offset by CO_2 used in photosynthesis
(1)
- less impact on global warming / climate change
(1)
- uses less of a finite resource (which can then be used in other processes e.g. manufacture of pharmaceuticals)
(1)
- less pollution from sulfur impurities / less SO_2 emissions
(1)
Allow ethanol can be made from a renewable resource Ignore esterification of vegetable oils (biodiesel)
Allow fermentation is a low energy process
Allow bioethanol is (nearly) carbon neutral / has a lower carbon footprint
Ignore 'crude oil is non-renewable'
Comment - allow reverse arguments in context of E5