From Clarkson University
"Biofuels are fuels made from recently grown plant or animal matter. Fossil fuels were also originally plant or animal matter, but that material has spent millions of years underground in extreme conditions and so it has changed significantly and its energy value was concentrated. As fossil fuel supplies diminish, renewable energy resources that can be replenished faster than we use them must be found in order for society to continue functioning as we are accustomed. Some folks believe that biofuels, like corn ethanol and biodiesel, could supply this renewable supply of fuel.
Goal: To understand the magnitude of transportation energy use, the process and implications of biofuel production, and the energy displacement potential of biofuels.
Key Concepts:
2. Carbon in the biomass was recently captured from the atmosphere through photosynthesis.
3. Combustion of biofuels emits “biogenic” CO2. Since this carbon is essentially recycled from the atmosphere, it is not considered to be as bad as the release of fossil carbon from the combustion of fossil fuels. That carbon had previously been sequestered underground.
4. Biofuels can often be made from“waste”materials.Inparticular,biodieselcanbe made from waste vegetable oil (e.g., fryer fat).
5. A diesel engine is capable of running on raw vegetable oil,but it must be pre-heated to lower the viscosity. Biodiesel has a lower viscosity than pure vegetable oil.
6. If crops are grown for the purpose of creating biofuels,there maybe significant environmental impacts associated with feedstock production.
7. Biofuel production requires feedstock production, feedstock processing, fuel production, and fuel use. It is important to consider environmental implications of all these “lifecycle” stages.
8. The increased use of biofuels is currently mandated by the U.S. federal government under the Energy Independence and Security Act of 2007. The goal is to produce and consume 36 billion gallons of biofuels per year by 2022. That includes 15 BGY of corn ethanol by 2015.
9. Currently,large-scale biofuel production relies on large-scale agricultural production of feedstock biomass. The feedstock production phase, especially in the case of corn ethanol relies on significant fossil fuel use and contributes to various environmental impacts.
10. The production of 5-6 billion gallons of ethanol in 2007 displaced only a small percentage (~2%) of our transportation energy use. An increase to 15 BGY by 2015 will put a significant burden on agriculture, food prices, and fossil fuel use, while still displacing only a small fraction of our transportation energy.
11. Fuels have different heating (calorific) values and different viscosities. These differences affect engine performance."
