lecture 9

Question 1

sustainable development

Answer 1

• Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs

Question 2

energy balance

Answer 2

An energy balance can compare:

1. the energy required to produce a biofuel
2. the embedded energy within a biofuel
3. the embedded energy within a fossil fuel alternative

Question 3

energy balance

Answer 3

Values 1 between 2 have questionable advantages: • 0.3 to 3.2 for biodiesel from soya
• 1.0 to 3.0 for biodiesel from rape seed
• 6 to 10 for biodiesel from oil palm
• 8 for wind power
• 10 to 15 for fossil fuels • 30 for SRCW
• 32 to 36 for miscanthus

Question 4

EU sustainability criteria

Answer 4

Biofuels must achieve GHG savings of at least 35%, rising to 50% from 2017
• Biofuels must not be derived from raw materials obtained from land enjoying high biodiversity value
• Biofuels must not be made from raw materials obtained from land with high carbon stocks
• Biofuels must not be produced from crops grown on land that was peatland in January 2008.

Question 5

GG balance

Answer 5

Combustion of biofuel is CO2 neutral?
• Production, processing and transport emit greenhouse
gases (GHGs): both CO2 & N2O
• Nitrogen fertilizer is especially bad
• Biofuel may offer GHG saving compared to fossil fuels
• Land use change may nullify any GHG savings from the use of biofuels

Question 6

enviro impacts- water

Answer 6

Energy derived from biomass requires 70 to 400 times more water than that derived from other energy sources, e.g. fossil fuel, wind & solar
• If current food and environmental trends continue, a water crisis will emerge in many parts of the world
• The production of biofuels increases demands on this already pressurised resource
• Biofuel production can have serious consequences for water quality through increased eutrophication

Question 7

carbon debt

Answer 7

• Carbon debt is the time required to balance GHG emissions from land use change against any GHG savings from using biofuels
• Deforestation mobilises vegetation (plant carbon) and soil carbon and may lead to a carbon debt which renders the GHG mitigation potential of biofuels questionable for decades

Question 8

are biofuels sustainable

Answer 8

Are Biofuels Sustainable?
• Depends on the definition of sustainable
• Land area – if all UK agricultural land supplied biodiesel,
it would meet only 57% of current fuel requirement
• To feed a growing population will require more, not less, agricultural land
• Water availability is an issue for many countries and is likely to get worse
• Some biofuel crops are more sustainable than others
• Only bioethanol from sugar cane should be considered
sustainable
• Land use change may nullify any potential GHG savings from the use of biofuels for a long time
Is the Biofuel Industry Sustainable?
• The introduction of biofuels was a policy, not market, decision
• Sustainability criteria and auditing are governmental decisions
• The biofuel industry is economically and socially valuable
• 1st generation biofuels have successfully developed a biofuel industry but cannot be considered sustainable (except for sugar cane)
• 2nd generation biofuels have the potential to be more sustainable but production is likely to fall for the same area of land
• 3rd generation will need to overcome water and energy issues to be considered sustainable