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CU-Boulder PHYS 3070 - Lecture Notes

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1Reminders:Extra Credit #4 due today in class.Homework #7 due today at 5 pm.Exam #1 on Friday, October 24 in class. Bring textbook and calculator.Research Project #1 due on Friday, October 31 in class(no emailed in papers accepted).Extra Credit #5:Upcoming Panel Discussion: "Do we Need a "Manhattan/Apollo Project" To Solvethe Energy/Climate Problem?"Thursday, October 307:00 PM - 9:00 PMCU-Boulder, Eaton Humanities Room 150Free and Open to the PublicView Flyer: http://sciencepolicy.colorado.edu/outreach/ecc2_flyer.pdfWrite a one page essay on a couple of interesting things you learned and what you think from the science you know.Due in class on Friday, November 8, 2008.Wood is biomass.Presently it represents about 3% of the total US energy consumption. This makes it one of the big “renewable”sources along with hydroelectric.Much of it is for direct heating.Pellet stove concept• Efficient, clean, uses “cheap wood” (scraps).• Still more $$$/BTU than gas or oil.• Need electricity for blowers, feeders.About 6.5 GigaWatt of “installed” capacity of electrical production. Often used for running a factory or local industry, but not on the electric grid.This is less than 10% of hydroelectric, which is about 100 GW. The total in the USA is 900 GW.Careful about cutting down too many trees (i.e. “renewable”);2There are programs to develop fastergrowing trees. What about growing grasses that can grow in more places than trees?Do not forget about the water input issue.One thing to consider is the CO2equation.Why is burning trees “carbon neutral” (produces no net excess of CO2in the atmosphere), but burning fossil fuels is different? What is carbon neutrality?The amount of CO2taken out of the atmosphere by the plants (in the growing process) is equal to the amount of CO2put back into the atmosphere by “burning” or “processing” the biomass (i.e. plants). What about ethanol from corn or other products?Note that ethanol does not come from burning corn in a stove!United States has a tariff on imported ethanol from sugarcane (through 2009).3Energy Related Press ReleasesWho is this person?January 17, 2007 - Grassley, Salazar Introduce Resolution Recognizing Need for Renewable EnergyJanuary 25, 2007 - Grassley Objects to Idea of Lifting U.S. Tariff on Ethanol ImportsJanuary 30, 2007 - Grassley Urges Energy Secretary to Consider Need to Retain Tariff on Ethanol ImportsJanuary 31, 2007 - Grassley Comments on Administration Farm Bill ProposalMarch 2, 2007 - Grassley Expresses Concern Over Possible U.S.-Brazil Partnership on EthanolUnited States Senator Grassley (Iowa)Lots of Processing to Make EthanolWhat is FFE in this Figure from the textbook?Answer: Fossil Fuel Energy inputDoes this change the carbon neutrality of this biomass?“Let Cowboy Energy help you beat the high cost of gasoline. Build and operate your personal ethanol still with the materials offered on this web site. Ethanol not only saves you money but releases lower amounts of green house gas emissions into the environment than regular gasoline.”“Energy Independence”Two things to note:1. You need a license to run an ethanol still ☺2. Much of the ethanol focus is on “energy independence”, and has little to do with environmental concerns!How much does the ethanol creation process rely on fossils fuels? A. Not at all - it's a classic form of using solar energy to create "biofuel".B. Only a tiny (negligible) amountC. At almost every step of the way.C is correct - take a look at Fig 5.13Assuming that the amount of energy from fossil fuels consumed in the ethanol creation is a fair bit less than the amount made available in the ethanol—is it a good candidate for a gasoline replacement? Why or why not?Clicker QuestionWhat was missing in this picture?Fossil Fuel Input for FertilizerEnergy Input in Wet MillsTractors and Farm EquipmentEnergy Input for DistillationThe 2001 Net Energy Balance of Corn-Ethanol* Note that this is one study (linked to from the Iowa State web page). Other studies numbers differ.4At the turn of the 20th century, scientists warned that the world's population would soon outpace global food production. One promising solution was to create a fertilizer containing nitrogen. Nitrogen is a prime nutrient for plants; adding more nitrogen to fields would boost agricultural production. In 1908 Fritz Haber discovered a chemical process for “fixing nitrogen.” Won the Nobel Prize in 1920 for “improving the standards of agriculture and the well-being on mankind.” Process requires very high heat and pressure (lots of energy input from fossil fuels).“On April 22, 1915, Haber was at the front lines directing the first gas attack in military history. About 150 tons of chlorineblew across the fields of Flanders, Belgium, spreading panic and death among the British and French.”United States had an excess capacity for producing Ammonium Nitrate after World War II. This is one of the biggest energy inputs for farming. Note that it has increased the yield of corn per acre by more than a factor of 3 and reduces the need for crop rotation.In Iowa there are “Blue Baby Days” when they recommend that small children not drink the water. This is from large run-off of nitrogen compounds some of which can bind to hemoglobin. Major pollution downstream into Gulf of Mexico.Some 90 years after Haber's invention, a Pew Oceans commission says nitrogen fertilizer has become the main source of pollution in the ocean.This particular study finds:06.1=tEnergyInpuutEnergyOutpHowever, there are other byproducts from the corn. Thus, perhaps we should not count all of the input energy for the ethanol.67.1=tEnergyInpuutEnergyOutp* This accounting depends on whether you need or want a scaled up amount of these other products.Clicker QuestionLots of products come from chemical processing of corn.Glucose, fructose, corn gluten meal, corn oil, maltodextrin, sorbitol, mannitol, xanthan gum, dextrins, cyclodextrins, monosodium glutamate, lactic acid, …Should we exclude thefraction of the energy input that we associatewith the byproducts, notthe ethanol?A) YesB) NoC) It depends what thecalculation is


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CU-Boulder PHYS 3070 - Lecture Notes

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