5th International Conference : Garvin Heath

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5th International Conference : Garvin Heath

  1. 1. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.Harmonizing Greenhouse Gas EmissionsEstimates for Electricity Generation Systems:A US approachICARB ConferenceMarch 13, 2013Garvin Heath, PhDNational Renewable Energy Laboratorys
  2. 2. NATIONAL RENEWABLE ENERGY LABORATORYNREL Snapshot• Leading clean-energy innovation for 35 years• 1740 employees with world-class facilities• Campus is a living model of sustainable energy• Owned by the Department of Energy• Operated by the Alliance for Sustainable EnergyOnly US national laboratory dedicated solelyto energy efficiency and renewable energy
  3. 3. NATIONAL RENEWABLE ENERGY LABORATORYScope of MissionEnergy Efficiency Renewable Energy Systems Integration Market FocusResidentialBuildingsCommercialBuildingsPersonal andCommercialVehiclesSolarWind and WaterBiomassHydrogenGeothermalGridInfrastructureDistributedEnergyInterconnectionBattery andThermal StorageTransportationPrivate IndustryFederal AgenciesDefense Dept.State/Local Govt.International
  4. 4. NATIONAL RENEWABLE ENERGY LABORATORYExpertise and Tools for Informed Decisions• Renewable Integration Analyses for easternand western US – production/transmissionplanning• System Advisor Model – software tool fordetermining economic value of proposedsolar, wind and geothermal projects• OPEN EI energy information data platform –linking and sharing data worldwide• LCA Harmonization study – consistent basisto compare life cycle GHG emissions forenergy technologiesAnalysis
  5. 5. NATIONAL RENEWABLE ENERGY LABORATORYWhy LCA?Power Sector GHG Emissions (as an example)5“One third of US CO2 emissions from power sector”But…– Only stack emissions considered (typically)• Renewables assigned ~zero emissions• Emissions associated with fuel extraction &transport, chemicals, etc. assigned to differenteconomic sectors– Only CO2 emissions counted(typically)
  6. 6. NATIONAL RENEWABLE ENERGY LABORATORY 6Life cycle assessment (LCA) –quantifies resource consumption,energy use, and emissions, fromcradle-to-grave• Practiced for 40 years• Methods codified in standards (e.g.,ISO) and guidelines, though somemethodological issues persistSelected by IPCC as most appropriatebasis for consistent comparison ofrenewable and conventional energytechnologies in Special Report onRenewablesQuantifying Attributable ImpactsSource: IPCC SRREN
  7. 7. NATIONAL RENEWABLE ENERGY LABORATORYLife Cycle Assessment: A PrimerMajor Stages:• Raw materials, feedstocks and fuelsacquisition• Equipment manufacture• Unit siting and construction• Operation of generating units• Transmission and distribution• Materials, fuel, and wastetransportation• Waste disposal• Unit decommissioning and disposal7Metrics• GHG emissions• Water consumption and discharges• Energy use• Petroleum use• Raw material consumption• Air pollutant emissions• Solid wasteSource: ORNL
  8. 8. NATIONAL RENEWABLE ENERGY LABORATORY 8System Boundary in LCA – Unifying concept withdiffering applicationnon-renewableenergynon-renewablematerialsemissionsenergyfinal productnet emissionsemissionsemissionsemissionsemissionsemissionsemissionsraw materialsraw materialsenergyenergyenergyenergyenergy energywaste materialsIntermediatefeedstockIntermediatefeedstockIntermediatefeedstockExtractionprocessProcess ProcessProcessWastedisposalExtractionprocessProcessofInterestLife cycle system boundary
  9. 9. NATIONAL RENEWABLE ENERGY LABORATORYDepth and Breadth of LCA at NREL1992 20129
  10. 10. NATIONAL RENEWABLE ENERGY LABORATORYSpecial Issue of Journal of Industrial Ecology onMeta-Analysis of LCAIssue Publication date: May, 201210Systematic Review and Harmonization ofLCAs of Electricity GenerationTechnologies: LCA Harmonization Project
  11. 11. NATIONAL RENEWABLE ENERGY LABORATORYNeed for Systematic Review & Meta-AnalysisContext– Considerable previous work in assessing life cycleenvironmental impacts of electricity generationtechnologies• Scrutinized > 2,000 references to date– Lack of holistic evaluation of this work in aconsistent manner, especially across technologies– Methodological inconsistency has hamperedcross-study comparisons– Result is impression amongst decision makers thatstate of the science is inconclusive11
  12. 12. NATIONAL RENEWABLE ENERGY LABORATORYNeed for Systematic Review & Meta-AnalysisContext– Considerable previous work in assessing life cycleenvironmental impacts of electricity generationtechnologies• Scrutinized > 2,000 references to date– Lack of holistic evaluation of this work in aconsistent manner, especially across technologies– Methodological inconsistency has hamperedcross-study comparisons– Result is impression amongst decision makers thatstate of the science is inconclusiveLCA Harmonization Study goals– Understand range of published results– Reduce uncertainty and inconsistency aroundestimates of environmental impacts of electricitygeneration technologies– Make the information useful to decision makers inthe near term12
  13. 13. NATIONAL RENEWABLE ENERGY LABORATORYMajor OutcomesContribution to important studies– IPCC SRREN: comprehensive assessment ofestimates of GHG emissions from electricitygeneration technologies (renewable andconventional)– Renewable Electricity Futures: 80% RE by2050Contribution to science– Special issue of Journal of IndustrialEcology on meta-analysis of LCAs• Publication date early May, 2012• 8 articles from project in special issue– Special sessions at International LCAconferences on meta-analysisof energy LCAs13
  14. 14. NATIONAL RENEWABLE ENERGY LABORATORYLiterature Review CountsNote: Some double counting is inherent in the Totals given that some references investigate more than one technology.Note2: The counts represent progress to-date and will differ from final results once the project is completed.Technology CategoryReferencesReviewedPassing theFirst ScreenPassing theSecondScreenProviding LifeCycle GHGEmissionsEstimatesBiopower 369 162 84 52Coal 273 192 110 52Concentrating solar power 125 45 19 13Geothermal 46 24 9 6Hydro 89 45 11 11Natural gas 251 157 77 40Nuclear 249 196 64 32Ocean energy 64 30 6 5Oil 68 45 19 10Photovoltaics 400 239 75 26Wind 231 174 72 49Totals 2165 1309 546 296% of total reviewed 60% 25% 14%% of those passing first screen 42% 23%% of those passing second screen 54%14
  15. 15. NATIONAL RENEWABLE ENERGY LABORATORYLarge Variability for Some Techs,RE Considerably Lower than Fossil15IPCC SRRENSPM Fig 8
  16. 16. NATIONAL RENEWABLE ENERGY LABORATORYLit. Review Methods and CaveatsMethodsLiterature collection– > 2,000 reviewed– Exhaustive search of Englishlanguage publications– All pub types (articles, reports,conf papers, theses…)Literature screening– Quality methods of LCA andGHG accounting– Transparency of reportinginputs, assumptions, and results– Relevance of evaluatedtechnology today/near futureCaveatsDistributions of literature estimates– Not assessment of likelihood– Not a prediction, though newerdesigns included– Might not capture true min., max.,or central tendency (countered byrepeated study of manytechnologies)Limited to available literature– Not all technology variationsstudied or studied frequentlyTechnologies considered in isolation– System impacts typically notstudied (↑reserves for ↑ wind)– Typically do not consider fleet ofexisting units (could weighttechnologies by deployment toestimate)– Land use change not considered(or removed)16
  17. 17. NATIONAL RENEWABLE ENERGY LABORATORYHarmonization MethodsTypes of HarmonizationSystem Harmonization– System boundaries– GWPs– GWIs (full harmonization)Technological Harmonization– Plant performancecharacteristics (eff., CF,)– LifetimeGeographic Harmonization– Solar resourceMethod1. Proportional adjustment ofdenominator of:2. Addition or subtraction forsystem boundary3. Full harmonization:Recalculation of GWI xmaterial mass (activity) forwhole LCI17GWP weightedlifetimeGHGGHGI PR LT Aη−=× × × ×
  18. 18. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – Published estimates18050100150200250all values mono-crystallinesilicon(m-Si)poly-crystallinesilicon(p-Si)amorphoussilicon(a-Si)cadmiumtelluride(CdTe)nano- crystallinedye sensitized(DSC)concentrator ribbonsiliconcadmium selenidequantum dot(QDPV)LifeCycleGHGEmissions(gCO2e/kWh)count: 124 30 56 12 13 4 6 2* 1references: 26 9 15 3 3 1 2 2 1KEY TO BOX PLOTMAX75thMEDIAN25thMIN
  19. 19. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – Harmonization steps191. Lifetime average module efficiency (solar energy converted to DCelectricity)a) 13% monob) 12.3% multi2. System lifetime: 30 yrs3. Irradiation: 2,400 kWh/m2/yr4. Performance ratio (ratio of AC electricity produced to DC-rated moduleefficiency and irradiation)a) rooftop + Bldg-integrated = 0.75b) ground = 0.8
  20. 20. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – As-Published20050100150200
  21. 21. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – Module Efficiency21050100150200
  22. 22. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – System Lifetime22050100150200
  23. 23. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – Irradiation23050100150200
  24. 24. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV – Performance Ratio24050100150200
  25. 25. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV– Harmonized vs. Published25050100150200
  26. 26. NATIONAL RENEWABLE ENERGY LABORATORYCrystalline PV– Harmonized vs. Reported26050100150200250Reported Harmonized Reported Harmonized Reported Harmonized Reported Harmonized Reported HarmonizedLifeCycleGHGEmissions(gCO2e/kWh)All Studies mono-Si multi-Si Ground-mounted Roof-mountedEstimates: 41 13 28 11 30References: 13 4 13 5 9
  27. 27. NATIONAL RENEWABLE ENERGY LABORATORYPublished Estimates for Harmonized Techs27
  28. 28. NATIONAL RENEWABLE ENERGY LABORATORYMethodological Harmonization ReducesVariability and Clarifies Central Tendency28
  29. 29. NATIONAL RENEWABLE ENERGY LABORATORYLessons learned– Significant set of existing literature (490 passing screens,and counting!)• Meta-analyses of LCA literature are rare, but opportunity to gain insight fromexisting literature is considerable– Considerable variability within pool of studies analyzed• Variability across technologies within a class can be significant• Variability within technologies can also be significant• Variability across technology classes significant, but yet not analyzed– Best performed after harmonizing studies within technologies/classes– Probably not appropriate to compare broad technology classes given significantvariability across technologies within those classes– Methodological inconsistency is prevalent• Many dimensions of inconsistency can be harmonized• Some are “legitimate” differences in assumptions29
  30. 30. NATIONAL RENEWABLE ENERGY LABORATORYLessons learned (II)Harmonization can• Reduce variability• Increase consistency• Facilitate cross-study comparisons• Identify key drivers30
  31. 31. NATIONAL RENEWABLE ENERGY LABORATORYHarmonization Caveats and ResponsesFor some users, only system harmonization is appropriate– For others, results after all steps of harmonization usefulTransparent results and methodsResults express variability around a modern reference systemOutline approaches to adjust our results to other assumptionsNot a true sensitivity analysisMost effective harmonization steps help identify influentialparameters (for NG  efficiency, fuel cycle methane leakage)Precision vs. accuracy– Accuracy still an issue for NG: missing factors, new scienceRecommended research
  32. 32. NATIONAL RENEWABLE ENERGY LABORATORYAcknowledgements and Pointers32Funding from US DOE / EERESpecial Issue on Meta-Analysis of LCAhttp://jie.yale.edu/LCA-meta-analysis• NG article pending response to peer reviewcommentsNREL LCA Harmonization projectwww.nrel.gov/harmonizationData visualization and download:en.openei.org/LCA
  33. 33. NATIONAL RENEWABLE ENERGY LABORATORYContributors33NREL: Ethan Warner, Patrick ODonoughue,Stacey Dolan, David Hsu, John Burkhardt,Pamala Sawyer, Martin Vorum, Elliot Cohen,BNL (PV): Vasilis Fthenakis, Hyung Chul Kim,Symbiotic Engineering (coal): Michael Whitaker
  34. 34. NATIONAL RENEWABLE ENERGY LABORATORYLeading the Way to a Clean Energy FutureGarvin.Heath@nrel.gov

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