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Introduction to the ethanol fuel debate.
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2. What is Ethanol? H H H H C C O H H Properties Appearance Colourless liquid - volatile and flammable Melting Point -114.3C Boiling Point 78.4C Solubility in water Fully miscible 3. Think
4. Uses ofEthanol? 5. ...and been used as a fuel since 1908! 6. Where does ethanol come from? Yeast acts on glucose sourced from plant matter such as sugar or corn to produce ethanol. This is a renewable energy source that is carbon neutral. Some are worried about food being diverted into fuel, raising world food prices. Fermentation Steam, high temperature and a catalyst turns ethene into ethanol with no by products. Ethene is made from cracking longer carbonchains found in fossil fuels. So this process is non-renewable.From Ethene 7. Cracking
8. Cracking - example + hexane butane ethene C C C C C C H H H H H H H H H H H H H H H H H H C C H C C C C H H H H H H H H H 9. Ethanol Production from Oil 5 parts Ethene is added to3 parts water Chemical Reaction 300 C60-70 atm Phosphoric(V) acid catalyst Un-reacted gases recycled Cooling the mixture causes the ethanol to dropout as a liquid Pure Ethanol Long chain hydrocarbons from fossil fuels are cracked and distilled to make ethene 10. Fermentation Carbohydrate e.g. glucose C 6 H 12 O 6 Ethanol+ Carbon Dioxide Yeast 2C 2 H 5 OH + 2CO 2 11. Fermentation But wait!Isnt Carbon Dioxide a Greenhouse Gas?We just said that this process was Carbon Neutral! Yes, but we must think about the whole carbon cycle.The carbohydrate will have originally been made by photosynthesis by the plant, which would have removed exactly the same amount of CO2 from the atmosphere.GlucoseEthanol+ Carbon Dioxide Yeast C 6 H 12 O 6 2C 2 H 5 OH + 2CO 2 12. Where does the carbohydrate come from? High-input annual grass, mostly grown in the USA and is subsidized around $1.90 a gallon [1]. Output from one hectare:31003900 Litres 1020% Greenhouse-gas savings versus petrol Production in 2007: 6,000 Million gallons Long-season annual grass, grown in tropical and subtropical climates.Output from one hectare:53006500 Litres 8796% Greenhouse-gas savings versus petrol Production in 2007: 5,000 Million gallons Instead of growing a crop specially for fermentation, organic waste products can be diverted from landfills.This prevents large amounts of landfill methane production. Methane has 70x the warming effect of CO2. [2] Limited total market. Corn Sugar Cane Waste Biomass A B C [1] http://www.economist.com/displaystory.cfm?story_id=10250420[2]2007 IPCC AR4Other statistics from Nature 444 (December 7, 2006): 673-676. 13. Ethanol from Corn Fermentation The Food versus Fuel Debate
[1] Economist 2007[2]April 2008 World Bank 14. Why is Sugar cane not aclear winner then?
15. V Weighing the Benefits 16. V With higher oil prices or extra ethanol subsidies Weighing the Benefits 17. Ethanol: A fuel for the 21 stCentuary? National Geographic estimated that oil production will peak soon and run out by 2060. Oil prices reached $147 per barrel in July 2008 compared to$24 per barrel in the 90s.Hence the world is looking for cheaper energy. The IPCC estimates a 2-3 temperature rise by 2100.This will have massive impact on ecosystems and global climate.CO2 increases this warming. 18. What is the UKs Policy on Biofuels?
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