Biofuels: Environmental Friend or Foe?

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Biofuels Environmental Friend or Foe?

• Presentation to 1st Year
• Environmental Engineering Students
• Deniz Karman

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• What are biofuels?
• Why biofuels?
• Why not biofuels?
• Life-cycle analysis

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• Primary energy sources
• Coal
• Oil
• Natural gas
• Hydro
• Nuclear
• Solar
• Wind
• Biomass

Fossil fuels

• Energy carriers
• Electricity
• Hydrogen
• Energy conversion systems for transportation
• IC engines
• Electric vehicles (EV)
• IC-electric hybrids
• Fuel cell vehicles (FCV)
• FCV hybrids

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Grain
Corn
Ethanol C2H5OH
SugarCane
Cellulosic Material
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• Biodiesel feedstocks
• Oilseeds
• soybean, canola (rapeseed)
• - Waste oil
• - Animal sources

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Biofuels

• Can we quantify the positive and negative impacts
  to make an overall assessment?
• Some easier than others, e.g.
• CO2 emissions vs biodiversity
• or,
• Socio-economic factors
• Case study CO2 reductions how much?

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(Oxburgh 2008)
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• Life cycle analysis

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• How are the CO2 emissions per unit energy in the
  previous chart calculated?
• The combustion of ethanol emits the same quantity
  of CO2 per unit energy regardless of the sources
  of the ethanol.
• If the C in the ethanol comes from biomass, it
  was captured from the atmosphere and does not
  represent a net emission
• The difference in the emissions results from the
  energy use during the cultivation and processing
  of the feedstock to obtain the ethanol
• Thus we cannot look at just the emissions during
  combustion and must do a life-cycle analysis to
  quantify the CO2 emissions

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• The phases in the life of a product
• We can identify the energy requirements and
  environmental emissions associated with each
  phase.
• Life-cycle analysis aims to quantify these.
• Recycling avoids some (but not all) of these
  energy requirements and emissions.

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• The life-cycle of a paper grocery bag.
• Recycling paper avoids some (but not all) of
  these energy requirements and emissions.
• Alternatively, plastic (polyethylene) grocery
  bags can be used.
• To compare the two options we need to complete a
  life-cycle analysis for both products.

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Life-cycle analysis for motor vehicles
Vehicle Cycle
Objective and quantitative evaluation of
environmental performance for fuel/vehicle
technologies
Pre-operation Material production, component
fabrication and vehicle assembly

• FUEL CYCLE

New vehicles
Upstream operations Feedstock and Fuel
production, transportation, storage, and
distribution
Vehicle operation energy conversion and
emissions from combustion
FUEL
Old vehicles
There are energy requirements and pollutant
emissions associated with each of these stages
Post-operation Vehicle disposal and recycling
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• Figure 2 Comparison of the greenhouse gases
  emitted by biofuels in comparison to those
  emitted by fossil fuels (petrol and diesel,
  EURO3). The emissions are broken down into the
  individual process of the value chain.

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• How can we try to capture some of the other
  factors that are relevant for comparing the
  environmental performance of alternative fuels?
• One example follows.

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• Figure 3
• Comparison of aggregated environmental impact
  (method of ecological scarcity, UBP 06) of bio
  fuels in comparison with fossil fuels (petrol,
  diesel and natural gas). The environmental impact
  is broken down by individual processes of value
  chain.

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• The method of ecological scarcity (UBP 06). . .
  estimates the total environmental impact from the
  difference between emission values and the legal
  limits.

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Conclusions

• Not all biofuels are the same in terms of their
  positive and negative effects.
• The motivation for and the effects of biofuels
  differ among different regions of the World
• Life cycle analysis is a MUST in assessing the
  environmental impacts of biofuels but may not
  give all the answers
• apples and oranges may need to be compared