Biofuels vs Fossil Fuels

Question 1

All biofeuls, when burnt, release what in the atmosphere?

Answer 1

CO2 - greehouse gas

Question 2

Why is releasing of CO2 in atmosphere of biogas termed carbon neutral?

Answer 2

They only replace CO2 back in atmosphere fro what was used by plants in photosynthesis. Hence, not increasing greenhouse gass levels or decreasing them. This is called carbon offset

Question 3

Compare renewability of Fossil Fuels vs Biofeuls

Answer 3

Fossil Fuels
Non-renewable
Biofuels
Renewable

Question 4

Describe greenhouse gas emmision for Fossil Fuels vs Biofeuls

Answer 4

Fossil Fuels
Produce CO2 and greenhouse gasses
Biofuels
Produces CO2 but is somewhat offsetted by fact that biofuels originate from photosynthesis which recently absorbed CO2 from atmosphere. Hence, carbon offset

Question 5

Give a few reasons why fossil fuels cannot be completely be ridden off

Answer 5

• Needed for production of polymers and other essential synthetic compounds
• Many transport facilities and machinery can only use fossil fuels
• Many industries and jobs are reliant on fossil fuels

Question 6

Describe reasons why biofeuls may cuase problems to society

Answer 6

• Need lots of land to grow crops for biofuel
• Food crops may be diverted to fuel production, away from people’s tables

Question 7

List the fossil fuel counter part for each biofeul

Answer 7

• Natural Gas <-> Biogas
• Petrol <-> Bioethanol
• Petrodiesel <-> Biodiesel

Question 8

List each biodiesel in order form which has closest heat content to its fossil fuel counterpart to farthest

Answer 8

1. Biodiesel (45 vs 42)
2. Bioethanol (48 vs 30)
3. Biogas (54 vs 26)

First number in brackets is Heat content for fossil fuel counterpart, second is heat content for biofuel

Question 9

Describe soem additional benefits of Biodiesel in terms of a substitute fro petrodiesel

Answer 9

• Similar chemical properties - means diesel vehicles can run on biodiesel with no modification to engines
• Similar amount of energy produced to petrodiesel
• Biodegradeable
• Non-toxic

Question 10

Why do biofuels generlly have a lower energy content than fossil fuels?

Answer 10

They are partially oxidised (contains oxygen)

Question 11

Describe relationship between oxidation state of carbon fuels and heat of combustion

Answer 11

Increase in oxidation state = Fall in heat of combustion