U3AOS1 - Fuel Choices

Question 1

Fossil Fuels vs Biofuels - Energy Content

Answer 1

Fossil Fuels - Higher:
Has not been partially oxidized, therefore, has more energy within it’s bonds

Biofuels - Lower:
Due to the presence of oxygen, biofuels have already been partially oxidized, and thus, will have less energy stored within its bonds

Question 2

Fossil Fuels vs Biofuels - Renewablity

Answer 2

Fossil Fuels - Non Renewable:
Formed from the decomposition of plant matter, and therefore produced at a constant rate - independent of rate of consumption

Biofuels - Renewable:
Produced from organic matter, which is renewable, since it can be grown to match rate of consumption

Question 3

Fossil Fuels vs Biofuels - Environmental Impacts (Combustion)

Answer 3

Both: Release Carbon Dioxide

Fossil Fuels - Contamination
Can be contaminated with harmful materials, such as nitrogen oxides and sulfur oxides - which can result in acid rain

Biofuels - Partially Carbon Neutral
The CO2 consumed by photosynthesis during biofuel production results in partial carbon neutrality

Question 4

Fossil Fuels vs Biofuels - Environmental Impacts (Sourcing)

Answer 4

Fossil Fuels - Destruction of Landscape
Production of fossil fuels requires invasive techniques - resulting in land degradation and erosion

Biofuels - Energy req to Grow
Energy is required for the production and transportation of the crops

Biofuels - Land Required
Requires a large amount of land, which can overtake the land required to grow food

Note: biofuels are only considered partially neutral

Question 5

Petrodiesel vs Biodiesel - Sources

Answer 5

Petrodiesel - Produced by fractional distillation of Crude Oil

Biodiesel - Produced from Organic Matter

Question 6

Petrodiesel vs Biodiesel - Chemical Structures

Answer 6

Petrodiesel: Non-Polar Chains

Biodiesel: Predominantly a Non-Polar chain, with an Ester Functional Group

Question 7

Petrodiesel vs Biodiesel - Combustion Products and Energies

Answer 7

Petrodiesel: Produces More Energy
Has not been partially oxidized, more energy stored within its bonds

Biodiesel: Produces Less Energy
Due to the ester functional group, it has been partially oxidized, and thus, will have less energy stored within its bonds

Petrodiesel: Contamination
Whilst petrodiesel itself is a pure hydrocarbon, it often is contaminated with nitrogen oxides and sulfur oxides

Biodiesel: Water Content
Due to its hydroscopic properties - it has a higher water content, which lowers the efficiency of combustion reactions

Question 8

Petrodiesel vs Biodiesel - Flow Along Fuel Lines and Storage Considerations

Answer 8

Petrodiesel: Lower Viscosity - Easier to Flow
Due to weaker intermolecular forces (just dispersion forces)

Biodiesel: Higher Viscosity - Harder to Flow
Due to stronger intermolecular bonds (dispersion forces, and permanent dipole-dipole bonds)

Petrodiesel: Not Hydroscopic
Non-Polar, and therefore, can be stored for longer without compromising the fuels quality

Biodiesel: Hydroscopic
Due to the ester group, which allows it to absorb more water than petrodiesel, which can compromise its quality

Question 9

Petrodiesel vs Biodiesel - Environmental Impacts

Answer 9

Petrodiesel: Non Renewable
Results from Oil, which is a fossil fuel

Biodiesel: Renewable
Produced from organic matter

Biodiesel: Biodegradable
Can be decomposed by living organisms such as bacteria and fungi

Petrodiesel: Releases other harmful materials
Biodiesel: releases less harmful materials