All; It would seem we need to separate "energy" from "petrolum energy equivalent", and "transportation energy" from energy as a whole. They often seem to be used identically in this discussion.
I have a specific question...does anyone have an estimate of the amount of oil from Venezuela that is from tar sands, what the EROI is, and what percent of the energy in that calcuation is from petroleum and natural gas (hopefully separately)? The major exporter of oil to the US is Canada. I understand that most of that oil is from tar sands, and it can only be done "economically" because of the cheap natural gas in Canada. Sincerely yours, Rob Harrison, Professor Soil & Environmental Sciences, College of Forest Resources Nutrition Project Head, PNW Stand Management Cooperative University of Washington, Box 352100 Seattle WA 98195-2100 ---------------------------------------------------------- [EMAIL PROTECTED] Email http://soilslab.cfr.washington.edu/ ---------------------------------------------------------- Phone 206-685-7463 Fax 206-685-3091 Ken Bagstad wrote: >Leslie et al - > >Im a bit surprised that the concept of Energy Return on Investment (EROI) >hasnt popped up yet in this discussion. EROI was pioneered in the early >1980s (see Cleveland et al. 1984, Energy and the U.S. economy: a biophysical >perspective, Science 225: 890-897). This work is over 20 years old, but to >my knowledge much-needed work is underway to update the numbers it presents. > In a nutshell, EROI is the number of barrels of oil (or other energy >source) that can be extracted using the energy equivalent of a single barrel >of oil. In other words, if you can extract 100 barrels of oil using 1 >barrel (100:1 EROI), this is a higher quality energy source than one that >only yields 10 barrels of oil per 1 barrel invested (10:1 EROI). > >For fossil fuel sources especially, you can imagine it makes sense to >deplete the high EROI sources first these are the cheapest and most >accessible. As a single well, oil field, or nation depletes its endowment >of fossil fuel, substantial energy may still be left in the ground, but it >gets progressively more expensive both in dollars and EROI to extract. >As you approach then drop below 1:1 EROI (that is, you get less than one >barrel of oil extracted for a single barrel spent), it obviously no longer >makes sense to continue, even if theres oil (or other energy) left in the >ground. Most techno-optimists say that advancing technology (or rising >prices) has made or will make formerly uneconomical sources of energy >profitable to extract, but theres no way to get around the fact that as you >approach or drop below 1:1 EROI, further extraction is a losing proposition. > The Canadian oil sands which we hear contain massive amounts of oil >similarly have much lower EROI than conventional oil, gas, etc. > >How does this relate to renewable energy? Solar, wind, etc. have lower EROI >than the easiest extractable fossil fuels (think of the fossil fuel energy >needed to manufacture, install, and maintain solar panels and wind >turbines), though of course they come without the nasty CO2 emissions, >mining impacts, and other pollutants of fossil power). Ethanol is an >interesting case what would first appear to be renewable actually needs a >massive subsidy of fossil fuel (think of the industrial, fossil-fuel >dependent agriculture needed to grow those giant fields of corn and soybeans >covering the Midwest and other parts of the US). So EROI of ethanol derived >from industrial agriculture isnt great. > >The upshot? As oil supplies become depleted, the second half of the oil >lying on the other side of the peak oil curve will be more expensive (in >monetary and energy terms) to extract. Couple this with rising demand >(especially in China and the developing world), and its hard to see how the >real cost of energy production wouldnt keep rising. As youve gathered >from the rest of this discussion, there are tradeoffs with all energy >sources, but considering EROI is an important piece in the public, policy, >and scientific discussions of our energy future. > >Regards, >Ken Bagstad > >Graduate Research Assistant, PhD program >Rubenstein School of Environment and Natural Resources >University of Vermont >Burlington, VT 05401 > > >
