Fossil Fuels, Ethanol, and Biodiesel By: Emma Wellman, Vishal Garg, and Tom Barch Seeking a responsible solution to global warming by decreasing greenhouse gas emissions

Our Hypothesis & Research Questions Biodiesel and Ethanol emit fewer greenhouse gases than do conventional fuels. Is it reasonable to replace conventional fuels with alternative fuels such as Biodiesel and Ethanol? In particular, is the energy balance with respect to Biodiesel and Ethanol sufficient to adopt them as fuels?

Our Roadmap What’s Wrong with the Status Quo? Ethanol: Benefits and Disadvantages Biodiesel: Benefits and Disadvantages Ethanol vs. Biodiesel Modeling Ethanol, Biodiesel, and Fossil Fuel Predictions Conclusions

What’s Wrong with Gasoline? Worldwide, 25-35% of anthropogenic CO 2 emissions are the result of transportation. 5% of these same CO 2 emissions are contributed by U.S. transportation. More SUVs + the same fuel economy standards = worse fuel economy. Other gases, such as nitrogen oxides and CO are pollutants emitted in the exhaust.

Atmospheric CO 2 is increasing * Slide from Lecture on 11/27 Net increase of 3.2 gigatons of CO2 per year

What is Ethanol? Fuel made from fermentation of corn or sugar mixed with gasoline. Mostly used for powering automobiles, but can be used in tractors and planes as well. E85 and E10 (with 85% and 10% ethanol respectively) are the most common blends. In 2004, almost 40% of the world’s ethanol was produced in Brazil.

The Benefits of Ethanol In 2004 U.S. ethanol use reduced CO 2 equivalent GHG emissions by 7 million tons. Renewable and biodegradable Net Energy Balance of 25% (good but not great) E85 emits 72% less CO 2 per km than gasoline. Ethanol burns cleaner and more completely than gasoline.

The Disadvantages of Ethanol The ethics of using food for fuel Production of large quantities of ethanol may require increased deforestation. Objectionable farming methods (fertilizers, factory farming, etc.) Cannot be transported in pipelines Potentially economically infeasible Contains less energy than gas

What is Biodiesel? An alternative fuel that can be made from a variety of renewable plant oils or animal fats. It is like diesel fuel, and is thus most effective for running diesel vehicles and heating. May be blended with petroleum diesel at any concentration or used in its pure form, B100. Since 2005, Willie Nelson has been selling B20 biodiesel in four states.

The Benefits of Biodiesel A Net Energy Balance of 93% makes it efficient to produce. The exhaust emissions of sulfur oxides and sulfates from biodiesel engines are negligible. Biodiesel emits 40% less CO 2 than conventional diesel. Emissions of various other pollutants are also lower: CO by 48%, particulate matter by 47%, hydrocarbons by 67%. It is biodegradable, non toxic, and produces few emissions.

The Disadvantages of Biodiesel NOx emissions from biodiesel are 10% higher than from diesel. Cost of production and cost of raw materials is high, although still lower than gasoline’s. Requires a great deal of land, which could lead to increased deforestation. When small quantities of water are added to biodiesel, it becomes less efficient and potentially dangerous.

Efficiency for Production of Ethanol and Biodiesel

Modeling Gasoline, Ethanol & Biodiesel We used a modified version of our Carbon Cycle Model in STELLA 8 to compare the Atmospheric CO 2 production of these three fuels. Using data reported by the U.S. Department of Energy, we then predicted the amount of CO 2 in the atmosphere fifty years from now depending on which fuel is used. The model and our results follow.

Our Modified STELLA Model

Predicted CO 2 emissions considering continued use of Fossil Fuels

Predicted Atmospheric CO 2 considering continued use of Fossil Fuels

Predicted Atmospheric CO 2 if we shift to use of Ethanol & Biodiesel

Our Extended Prediction

Conclusions & Further Considerations We can conclude that ethanol and biodiesel are suitable alternatives to gasoline and conventional diesel, though there are a few significant caveats: Biodiesel & Ethanol may be too costly (in terms of input/output of energy & environmental effects in production) to be feasible as complete replacements. Clearly however, they are reasonable transitional alternatives with far more environmentally responsible Greenhouse Gas emission rates.

Want More Information? More on Biodiesel: More on Ethanol: US Department of Energy:

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