sustainability

Question 1

hydrogen

Answer 1

renewable source: PEM (electrolytic cell), artificial photosynthesis

non renewable: natural gas

Question 2

ethanol

Answer 2

renewable energy source

can be produced from fermentation of glucose from plant matter

produces carbon dioxide however this is generally taken back in via photosynthesis

Question 3

diesel

Answer 3

renewable source: transesterification of animal and plant triglycerides

non renewable: obtained from crude oil

Question 4

methane and methanol

Answer 4

renewable: biogas from bio mass

non renewable: natural gas

Question 5

butane propane

Answer 5

sourced from crude oil

Question 6

biofuel sustainability, renewability and environmental impact and cost

Answer 6

renewability
- can be replenished in a relatively short period of time
- renewability depends on land, storage availability and water use which can be limited

environmental impact
- generally has no net carbon emissions
- while some production of biofuels can release CO2, this is taken back in via photosynthesis

• land use
• destruction of habitat
• can require fossil fuels for growing, harvesting and transporting

cost and infrastructure
- biofuels cost significantly more to produce compared to fossil fuels and they

Question 7

fossil fuels renewability, sustainability environmental impact and cost

Answer 7

renewability
- fossil fuels take millions of years to form and cannot be replenished at the rate that they are consumed

environmental impact
- greenhouse gas emissions contributing to global warming
- combustion of fossil fuels can contribute to harmful pollutants
- water pollution
- oil drilling
- fracking of crude oil

Question 8

greenhouse gases

Answer 8

• carbon dioxide: sourced from burning fossil fuels and contributes to global warming
• methane:
• water

Question 9

fuel cells benefits and disadvantages

Answer 9

advantages
- high efficiency due to porous electrodes
- quite operation
- can use a variety of fuels including ones that will not emit greenhouse gases
- catalysts can be used to enhance efficiency

Question 10

PEM

Answer 10

advantages
- no CO2 impact
- catalysts on anode and cathode increase efficiency
- can be powered by solar or wind energy

disadvantages
- requires large amounts of water

Question 11

artificial photosynthesis

Question 12

use of catalysts

Answer 12

strengths
- can increase rate of reaction, allowing reactions to occur at lower temp and pressure, reducing energy consumption and costs
- can be used to compromise conditions for equilibrium reactions that require low temperature for high yield
- can be reused
- can be used to favour production of specific products, enhancing selectivity and reducing unwanted by products

disadvantages
- disposal of certain catalysts lead to environmental issues

Question 13

compromising equilibrium conditions to achieve desired rate and yield