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Politics : Rat's Nest - Chronicles of Collapse -- Ignore unavailable to you. Want to Upgrade?

To: Wharf Rat who wrote (4486)	7/26/2006 8:52:51 AM
From: Wharf Rat	Read Replies (1) \| Respond to of 24206

For a definitive assessment of the value of ethanol and methanol please go to the following web site: petroleum.berkeley.edu Here is the abstract: This paper analyses energy efficiency of the industrial corn-ethanol cycle and brackets energy efficiency of the switchgrass-cellulosic ethanol cycle. IN particular, it critically evaluates the publications by Farrell et al. (2006a; 2006c) and Shapouri, Wang, et al. (Wang, 2001; Shapouri et al., 2002; Shapouri et al., 2003; Shapouri and McAloon, 2004). It is demonstrated that in a net-energy analysis of the industrial corn-ethanol cycle (Farrell et al., 2006a; Farrell et al., 2006c) did not (i) define system boundaries, (ii) conserve mass, and (iii) conserve energy. As already pointed out in (Patzek, 2004), most of the current First Law net-energy models of the industrial corn-ethanol cycle are based on nonphysical assumptions and should be discarded. The energy cost of producing and refining carbon fuels in real time, e.g., corn and ethanol, is high relative to that of fossil fuels deposited and concentrated over geological time. Proper mass and energy balances of corn fields and ethanol refineries that account for the photosynthetic energy, part of the environment restoration work, and the coproduct energy have been formulated. These balances show that energetically production of ethanol from corn is 2 - 4 times less favorable than production of gasoline from petroleum. From thermodynamics it also follows that ecological damage wrought by industrial biofuel production must be severe, see also (Patzek, 2004; Patzek and Pimentel, 2006). With maximum theoretical yield of ethanol and the DDGS coproduct energy credit, 3.9 gallons of ethanol displace on average the energy in 1 gallon of gasoline. Without the DDGS energy credit, this average number is 6.2 gallons of ethanol. Equivalent CO2 emissions from corn ethanol are 50% higher than those from gasoline, and become 100% higher if methane emissions from cows fed DDGS are accounted for. The U.S. ethanol industry has consistently inflated its ethanol yields by counting 5 volume percent of #14 gasoline denaturant (8% of energy content) as ethanol. Also, imports from Brazil and higher alcohols seem to have been counted as U.S. ethanol. A detailed analysis of 778 samples of 401 corn hybrids reveals that the highest possible yield of ethanol is 2.64 plus or minus 0.05 gal ethanol/per nominal wet bushel of corn. The commonly accepted USDA estimate of mean ethanol yield in the U.S., 2.682 gal EtOH/bu, is one standard deviation above the rigorous statistical estimate in this paper. From a mass balance of soil (Patzek, 2004), it follows that ethanol coproducts should be returned to the fields. The energy efficiency of current cellulosic ethanol production is poorer than that of any other industrially produced liquid biofuel (Patzek and Pimentel, 2006). Cherenkov on Wednesday July 26, 2006 at 4:18 AM EST theoildrum.com