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My Points I • Ethanol is and will be an important contributor to reducing our “petroleum addiction” • Focus needs to be on finding replacements for crude oil for liquid fuels—we need real solutions • Ethanol is one of a very few solutions available—gives high “return on petroleum invested” (about 2200% or 22 fold) • “Net energy” is a fundamentally wrong concept & even dangerous as a policy guide
My Points II • Corn ethanol is a good start for large scale ethanol and has generally positive features • Bridge to cellulosic ethanol • Improves rural economy • Reduces net farm subsidies • Can reduce greenhouse gases • Greatly reduces dependence on petroleum for liquid transportation fuels • Cellulose ethanol will have a much bigger positive impact than corn ethanol on these & other areas
Most Recent Pimentel & Patzek Study*- Some Serious Deficiencies and Errors • Define ethanol’s % net energy as: • [(Ethanol Heating Value (LHV) – Fossil Energy Inputs) /Ethanol Heating Value (LHV)] x 100 • All BTU are treated as equivalent (1 BTU coal = 1 BTU petroleum = 1 BTU natural gas = 1 BTU electricity = and so on) • Confound “fossil fuels” with “liquid fossil fuels”=petroleum • They calculate net energy for ethanol from: • Corn - 29% • Switchgrass - 50% • Wood - 57% • They make no comparisons with other liquid fuels • *Natural Resources Research, vol. 14, No. 1, March 2005 pgs. 65-76
Net Energy Reductio Ad Absurdum:the Accounting Analogy • “Net energy” is an energy accounting tool: a terrible one • Using the net energy approach of “All BTU are equal” BP’s accountants would calculate: • 100 U.S. $ + 100 Pounds Sterling + 100 French francs + 100 Deutschmarks = $400 U. S. • The math is right; the idea is absurd! • We cannot add up different forms of energy on a straight BTU basis any more than we can add up different currencies on a straight numerical equivalency basis • Different forms of energy have different qualities—just like different currencies do
Pimentel & Patzek Confound Fossil Fuels & Petroleum Used for Ethanol Production I *Out of 21 different inputs. Adapted from Tables 1 & 2 of Pimentel & Patzek, NRR, 2005.
Pimentel & Patzek Confound Fossil Fuels & Petroleum Used II • From previous slide, per P&P: • Total energy equals 6,597 kcal/liter ethanol • Total petroleum used equals 2,123 kcal/liter ethanol • “Net energy” calculation for corn ethanol • [(Ethanol Heating Value (LHV) – Fossil Energy Inputs) /Ethanol Heating Value (LHV)] x 100 • Thus [(5,130 - 6,597)/5,130] x 100% = -29% • Minimum “Net petroleum” • Thus [(5,130 - 2,123)/5,130] x 100% = +60% • I prefer “Petroleum Profit Ratio” = Kcal liquid fuel out per kcal of petroleum invested to make that fuel • Ratio for petroleum invested to make ethanol vs. petroleum invested to make gasoline is +2200%.
What Do Others Conclude about Pimentel and Patzek Studies? I* • “Studies** that reported negative net energy incorrectly ignored coproducts and used some obsolete data. • All studies (two by P&P and four others) indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline...” • Fig. 2. Ethanol yields (1.1/0.05) = 22x more liquid fuel than gasoline per unit of petroleum “invested” • *Farrell, et al, “Ethanol can Contribute to Energy and Environmental Goals” Science vol. 311. Jan. 2006 pg. 506-508 • **Refers to T. Patzek. Crit. Rev. Plant. Sci. 23, 219 (2004) & D. Pimentel and T. Patzek. Nat. Resource Res. 14, 65 (2005)
What Do Others Conclude about Pimentel and Patzek Studies? II* • “The large energy inputs reported by Pimentel & Patzek are [due to] a collection of conservative assumptions…” • “All studies (P&P + 3 others) indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline..” • For cellulosic ethanol, P&P results are an order of magnitude higher than the other 3 studies because P&P “assume that industrial process energy is generated by fossil fuel combustion and electricity rather than by lignin combustion”. • *R. Hammerschlag. Environ. Sci. & Technol. “Ethanol’s Energy Return on Investment: A Survey of Literature 1990-Present” in press 2006.
RIP “NET ENERGY” 1979 – 2005 “WE COME TO BURY NET ENERGY, NOT TO PRAISE IT”
Why should we bury “net energy”? I • Because it is a convenient fiction, an academic toy • Net energy doesn’t relate to the real world • It doesn’t serve good energy policy formation • Why? • Because it treats all energy from all sources (coal, oil, natural gas, solar, wind, hydro, etc) as equal • Confounds “fossil fuels” with petroleum used • Ignores energy quality, only deals with energy quantity • But all energy is NOT created equal
Why should we bury “net energy”? II • Professors Pimentel & Patzek have further separated net energy from reality: why?: • Because they don’t compare ethanol with real fuels • We have. According to their flawed “net energy” standard: • Ethanol is significantly better than gasoline, diesel, jet fuel ( ethanol is -29% vs. gasoline -37%) • Ethanol is enormously better than electricity (-235%)
Making Some Comparisons • I disagree with the fundamental premise of “net energy” analysis: “All BTU (kcal, erg) are created equal” They are not. • But let’s apply the “net energy” approach to other energy systems, for example: • Burn 3 kcal of coal or natural gas to get 1 kcal electricity • “Net energy” is negative 235% • But electricity is higher quality energy than coal • Refine 100 kcal of crude oil to produce 83.5 kcal of gasoline, diesel, jet fuel, residual oil, etc. • “Net energy” is negative 37% • But gasoline is higher quality energy than crude oil
Petroleum Refining Refining input 9.6 BTU Fuel out 83.5 BTU Gasoline, diesel, jet fuel, LPG, residual oil, etc Crude oil 100 BTU Other non fuel products Production & Distribution Input 4.5 BTU 83.5 BTU – 114.1 BTU NET ENERGY = =- 37 % (vs.-29%) 83.5 BTU
Electricity Generation From Coal Mining input 1 BTU Coal Electricity 100 BTU 31 BTU Generation & Distribution Input 3 BTU 31 BTU – 104 BTU NET ENERGY = = - 235 % (vs. -29%) 31 BTU
Fossil Energy Replacement Ratio:the Primary Climate Security Driver Energy Delivered to Customer Fossil Energy Ratio (FER) = Fossil Energy Used Source: J. Sheehan & M. Wang (2003)
Petroleum Replacement Ratio:the Primary Energy Security Driver Liquid Fuels Delivered to User Petroleum Replacement Ratio (PRR) = Petroleum Energy Used Adapted from Farrell, et al (2006)
A Question Follows: • Are we really going to stop burning coal for electricity or refining crude because their “net energy” is negative? • Heck no! – so let’s not apply that reasoning to ethanol • Unfortunately, that is exactly where the net energy analysis (mis)leadsus • It’s time to get real about energy…and the “net energy” idea is simply unreal
Logical Consequences • If “negative net energy” means anything, then: • Shut down all coal (& natural gas) electricity generation (70% of total) • Shut down all oil refineries—98% of vehicles • “Net energy” is a foolish argument • All energy production systems sacrifice some quantity of energy for increased energy quality
Summary • Professors Pimentel & Patzek are not dealing with the real world of our energy needs • Net energy” is fundamentally wrong & dangerous as a policy guide • Focus needs to be on: • finding replacements for crude oil • system designs that work • “Net energy” argument misleads us and misdirects our focus: extending & then replacing petroleum • Corn ethanol is and will be an important contributor to ending our dependence on petroleum • Cellulosic ethanol will do even more to replace petroleum with renewable fuels