Identifying and Calculating GHG Emissions - World Resources Institute

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Identifying and Calculating GHG Emissions - World Resources Institute

6Identifying and Calculating GHG EmissionsG U I D A N C EOnce the inventory boundary has been established, companies generallycalculate GHG emissions using the following steps:1. Identify GHG emissions sources2. Select a GHG emissions calculation approach3. Collect activity data and choose emission factors4. Apply calculation tools5. Roll-up GHG emissions data to corporate level.This chapter describes these steps and the calculation tools developed by the GHGProtocol. The calculation tools are available on the GHG Protocol Initiative websiteat www.ghgprotocol.org.G U I D A N C E40


CHAPTER 6 Identifying and Calculating GHG Emissions 41To create an accurate account of their emissions,companies have found it useful to divide overall emissionsinto specific categories. This allows a companyto use specifically developed methodologies to accuratelycalculate the emissions from each sector andsource category.FIGURE 9.Steps in identifying and calculating GHG emissionsIdentify SourcesSelect Calculation ApproachIdentify GHG emissions sourcesThe first of the five steps in identifying and calculatinga company’s emissions as outlined in Figure 9 is tocategorize the GHG sources within that company’sboundaries. GHG emissions typically occur from thefollowing source categories:• Stationary combustion: combustion of fuels instationary equipment such as boilers, furnaces,burners, turbines, heaters, incinerators, engines,flares, etc.• Mobile combustion: combustion of fuels in transportationdevices such as automobiles, trucks, buses,trains, airplanes, boats, ships, barges, vessels, etc.• Process emissions: emissions from physical or chemicalprocesses such as CO 2 from the calcination stepin cement manufacturing, CO 2 from catalytic crackingin petrochemical processing, PFC emissions fromaluminum smelting, etc.• Fugitive emissions: intentional and unintentionalreleases such as equipment leaks from joints, seals,packing, gaskets, as well as fugitive emissions fromcoal piles, wastewater treatment, pits, cooling towers,gas processing facilities, etc.Every business has processes, products, or services thatgenerate direct and/or indirect emissions from one ormore of the above broad source categories. The GHGProtocol calculation tools are organized based on thesecategories. Appendix D provides an overview of directand indirect GHG emission sources organized by scopesand industry sectors that may be used as an initial guideto identify major GHG emission sources.Collect Data and Choose Emission FactorsApply Calculation ToolsRoll-up Data to Corporate LevelIDENTIFY SCOPE 1 EMISSIONSAs a first step, a company should undertake an exerciseto identify its direct emission sources in each ofthe four source categories listed above. Process emissionsare usually only relevant to certain industrysectors like oil and gas, aluminum, cement, etc.Manufacturing companies that generate process emissionsand own or control a power production facility willlikely have direct emissions from all the main sourcecategories. Office-based organizations may not have anydirect GHG emissions except in cases where they own oroperate a vehicle, combustion device, or refrigerationand air-conditioning equipment. Often companies aresurprised to realize that significant emissions comefrom sources that are not initially obvious (see UnitedTechnologies case study).IDENTIFY SCOPE 2 EMISSIONSThe next step is to identify indirect emission sources fromthe consumption of purchased electricity, heat, or steam.Almost all businesses generate indirect emissions due to thepurchase of electricity for use in their processes or services.IDENTIFY SCOPE 3 EMISSIONSThis optional step involves identification of other indirectemissions from a company’s upstream and downstreamactivities as well as emissions associated withoutsourced/contract manufacturing, leases, or franchisesnot included in scope 1 or scope 2.The inclusion of scope 3 emissions allows businesses toexpand their inventory boundary along their value chainand to identify all relevant GHG emissions. This providesa broad overview of various business linkages andpossible opportunities for significant GHG emissionreductions that may exist upstream or downstream of acompany’s immediate operations (see chapter 4 for anoverview of activities that can generate GHG emissionsalong a company’s value chain).G U I D A N C E


Identifying and Calculating GHG EmissionsG U I D A N C ESelect a calculation approachDirect measurement of GHG emissions by monitoringconcentration and flow rate is not common. More often,emissions may be calculated based on a mass balance orstoichiometric basis specific to a facility or process.However, the most common approach for calculatingGHG emissions is through the application of documentedemission factors. These factors are calculated ratiosrelating GHG emissions to a proxy measure of activity atan emissions source. The IPCC guidelines (IPCC, 1996)refer to a hierarchy of calculation approaches and techniquesranging from the application of generic emissionfactors to direct monitoring.In many cases, particularly when direct monitoring iseither unavailable or prohibitively expensive, accurateemission data can be calculated from fuel use data. Evensmall users usually know both the amount of fuelconsumed and have access to data on the carbon contentof the fuel through default carbon content coefficients orthrough more accurate periodic fuel sampling.Companies should use the most accurate calculationapproach available to them and that is appropriate fortheir reporting context.Collect activity dataand choose emission factorsFor most small to medium-sized companies and for manylarger companies, scope 1 GHG emissions will be calculatedbased on the purchased quantities of commercialfuels (such as natural gas and heating oil) usingpublished emission factors. Scope 2 GHG emissions willprimarily be calculated from metered electricityconsumption and supplier-specific, local grid, or otherpublished emission factors. Scope 3 GHG emissions willprimarily be calculated from activity data such as fueluse or passenger miles and published or third-partyemission factors. In most cases, if source- or facilityspecificemission factors are available, they arepreferable to more generic or general emission factors.Industrial companies may be faced with a wider rangeof approaches and methodologies. They should seekguidance from the sector-specific guidelines on theGHG Protocol website (if available) or from theirindustry associations (e.g., International AluminumInstitute, International Iron and Steel Institute,American Petroleum Institute, WBCSD SustainableCement Initiative, International Petroleum IndustryEnvironmental Conservation Association).United Technologies Corporation:More than meets the eyeIn 1996, United Technologies Corporation (UTC), a global aerospaceand building systems technology corporation, appointed ateam to set boundaries for the company’s new Natural ResourceConservation, Energy and Water Use Reporting Program. The teamfocused on what sources of energy should be included in theprogram's annual report of energy consumption. The teamdecided jet fuel needed to be reported in the annual report; jet fuelwas used by a number of UTC divisions for engine and flight hardwaretesting and for test firing. Although the amount of jet fuelused in any given year was subject to wide variation due tochanging test schedules, the total amount consumed in anaverage year was believed to be large and potentially smallenough to be specifically excluded. However, jet fuel consumptionreports proved that initial belief incorrect. Jet fuel has accountedfor between 9 and 13 percent of the corporation's total annual useof energy since the program commenced. Had UTC not includedthe use of jet fuel in annual data collection efforts, a significantemissions source would have been overlooked.Apply calculation toolsThis section provides an overview of the GHG calculationtools and guidance available on the GHG ProtocolInitiative website (www.ghgprotocol.org). Use of thesetools is encouraged as they have been peer reviewedby experts and industry leaders, are regularly updated,and are believed to be the best available. The tools,however, are optional. Companies may substitute theirown GHG calculation methods, provided they aremore accurate than or are at least consistent with theGHG Protocol Corporate Standards approaches.There are two main categories of calculation tools:• Cross-sector tools that can be applied to differentsectors. These include stationary combustion, mobilecombustion, HFC use in refrigeration and air conditioning,and measurement and estimation uncertainty.• Sector-specific tools that are designed to calculateemissions in specific sectors such as aluminum, ironand steel, cement, oil and gas, pulp and paper, officebasedorganizations.42CHAPTER 6


CHAPTER 6 Identifying and Calculating GHG Emissions 43Most companies will need to use more than one calculationtool to cover all their GHG emission sources.For example, to calculate GHG emissions from analuminum production facility, the company would usethe calculation tools for aluminum production,stationary combustion (for any consumption ofpurchased electricity, generation of energy on-site, etc),mobile combustion (for transportation of materials andproducts by train, vehicles employed on-site, employeebusiness travel, etc), and HFC use (for refrigeration,etc). See Table 3 for the full list of tools.STRUCTURE OF GHG PROTOCOL CALCULATION TOOLSEach of the cross-sector and sector-specific calculationtools on the website share a common format andinclude step-by-step guidance on measuring and calculatingemissions data. Each tool consists of a guidancesection and automated worksheets with explanations onhow to use them.The guidance for each calculation tool includes thefollowing sections:• Overview: provides an overview of the purpose andcontent of the tool, the calculation method used in thetool, and a process description• Choosing activity data and emission factors: providessector-specific good practice guidance and referencesfor default emission factors• Calculation methods: describes different calculationmethods depending on the availability of site-specificactivity data and emission factors• Quality control: provides good practice guidance• Internal reporting and documentation: providesguidance on internal documentation to supportemissions calculations.ChevronTexaco: The SANGEA TM accounting and reporting systemChevronTexaco, a global energy company, has developed and implementedenergy utilization and GHG estimation and reportingsoftware consistent with the GHG Protocol Corporate Standard. Thissoftware is available free of charge and makes it easier, more accurate,and less costly to institute a corporate-wide GHG accountingand reporting system in the oil and gas sector. Called the SANGEA Energy and Greenhouse Gas Emissions Estimating System, it iscurrently in use at all ChevronTexaco facilities worldwide, comprisingmore than 70 reporting entities.The system is an auditable, Excel-and-Visual-Basic-based tool forestimating GHG emissions and energy utilization. It streamlines corporate-leveldata consolidation by allowing the inventory coordinator ateach facility to configure a spreadsheet, enter monthly data, and sendquarterly reports to a centralized database.In practice, the SANGEA system employs a variety of strategies toensure consistent calculation methods and ease company-widestandardization:• Spreadsheet configuration and material input information forspecific facilities can be carried over from year to year. Inventoryspecialists can easily modify configurations as a facility changes(due to new construction, retirement of units, etc.).• Updates are efficient. Methodologies for estimating emissions,emission factors, and calculation equations are stored centrally inthe software, easing updates when methodologies or defaultfactors change. Updates to this central reference are automaticallyapplied to the existing configuration and input data.Updates will mirror the timing and content of updates to theAmerican Petroleum Institute Compendium of GHG emission estimatingmethodologies.• The system is auditable. The software requires detailed audit trailinformation on data inputs and system users. There is documentedaccountability of who made any change to the system.• Using one system saves money. Significant cost savings areachieved by using the same system in all facilities, as comparedto conventional, disparate systems.ChevronTexaco’s one-off investment in developing the SANGEA systemhas already shown results: A rough cost estimate for ChevronTexaco'sRichmond, California, refinery indicates savings of more than 70percent over a five-year period compared with the conventionalapproaches based on locally developed reporting systems. SANGEA isexpected to reduce the long term expenses of maintaining a legacysystem and hiring independent consultants. Employing a combinationof the GHG Protocol Corporate Standards and SANGEA calculationsoftware to replace a diverse and confusing set of accounting andreporting templates yields significant efficiency and accuracy gains,and allows the company to more accurately manage GHG emissionsand institute specific emissions improvements.G U I D A N C E


Identifying and Calculating GHG EmissionsTABLE 3. Overview of GHG calculation tools available on the GHG Protocol websiteG U I D A N C ECROSS-SECTOR TOOLSCALCULATION TOOLSStationary CombustionMobile CombustionHFC from Air Conditioningand Refrigeration UseMeasurement and EstimationUncertainty for GHG EmissionsMAIN FEATURES.• Calculates direct and indirect CO 2 emissions from fuel combustion in stationary equipment• Provides two options for allocating GHG emissions from a co-generation facility• Provides default fuel and national average electricity emission factors• Calculates direct and indirect CO 2 emissions from fuel combustion in mobile sources• Provides calculations and emission factors for road, air, water, and rail transport• Calculates direct HFC emissions during manufacture, use and disposal of refrigeration and airconditioningequipment in commercial applications• Provides three calculation methodologies: a sales-based approach, a life cycle stage basedapproach, and an emission factor based approach• Introduces the fundamentals of uncertainty analysis and quantification• Calculates statistical parameter uncertainties due to random errors related to calculation ofGHG emissions• Automates the aggregation steps involved in developing a basic uncertainty assessment for GHGinventory dataAluminum and other non-Ferrous Metals Production• Calculates direct GHG emissions from aluminum production (CO 2 from anode oxidation, PFC emissionsfrom the “anode effect,” and SF 6 used in non-ferrous metals production as a cover gas)Iron and Steel• Calculates direct GHG emissions (CO 2 ) from oxidation of the reducing agent, from the calcinationof the flux used in steel production, and from the removal of carbon from the iron ore and scrapsteel usedNitric Acid Manufacture• Calculates direct GHG emissions (N 2 O) from the production of nitric acidAmmonia Manufacture• Calculates direct GHG emissions (CO 2 ) from ammonia production. This is for the removal ofcarbon from the feedstock stream only; combustion emissions are calculated with the stationarycombustion moduleSECTOR-SPECIFIC TOOLSAdipic Acid ManufactureCementLimeHFC-23 fromHCFC-22 Production• Calculates direct GHG emissions (N 2 O) from adipic acid production• Calculates direct CO 2 emissions from the calcination process in cement manufacturing (WBCSDtool also calculates combustion emissions)• Provides two calculation methodologies: the cement-based approach and the clinker-based approach• Calculates direct GHG emissions from lime manufacturing (CO 2 from the calcination process)• Calculates direct HFC-23 emissions from production of HCFC-22Pulp and Paper• Calculates direct CO 2 , CH 4 , and N 2 O emissions from production of pulp and paper. This includescalculation of direct and indirect CO 2 emissions from combustion of fossil fuels, bio-fuels, andwaste products in stationary equipmentSemi-ConductorWafer Production• Calculates PFC emission from the production of semi-conductor wafersGuide for SmallOffice-Based Organizations• Calculates direct CO 2 emissions from fuel use, indirect CO 2 emissions from electricityconsumption, and other indirect CO 2 emissions from business travel and commuting44CHAPTER 6


CHAPTER 6 Identifying and Calculating GHG Emissions 45In the automated worksheet section, it is only necessaryto insert activity data into the worksheets and to selectan appropriate emission factor or factors. Default emissionfactors are provided for the sectors covered, but it isalso possible to insert customized emission factors thatare more representative of the reporting company’s operations.The emissions of each GHG (CO 2 , CH 4 , N 2 O, etc.)are calculated separately and then converted to CO 2equivalents on the basis of their global warming potential.Some tools, such as the iron and steel sector tool and theHFC cross-sector tool, take a tiered approach, offering achoice between a simple and a more advanced calculationmethodology. The more advanced methods are expectedto produce more accurate emissions estimates but usuallyrequire collection of more detailed data and a morethorough understanding of a company’s technologies.Roll-up GHG emissions data to corporate levelTo report a corporation’s total GHG emissions, companieswill usually need to gather and summarize datafrom multiple facilities, possibly in different countriesand business divisions. It is important to plan thisprocess carefully to minimize the reporting burden,reduce the risk of errors that might occur whilecompiling data, and ensure that all facilities arecollecting information on an approved, consistent basis.Ideally, corporations will integrate GHG reporting withtheir existing reporting tools and processes, and takeadvantage of any relevant data already collected andreported by facilities to division or corporate offices,regulators or other stakeholders.The tools and processes chosen to report data willdepend upon the information and communication infrastructurealready in place (i.e., how easy is it to includenew data categories in corporate databases). It will alsodepend upon the amount of detail that corporate headquarterswishes to be reported from facilities. Datacollection and management tools could include:• Secure databases available over the company intranetor internet, for direct data entry by facilities• Spreadsheet templates filled out and e-mailed to a corporateor division office, where data is processed further• Paper reporting forms faxed to a corporate or divisionoffice where data is re-entered in a corporate database.However, this method may increase thelikelihood of errors if there are not sufficient checks inplace to ensure the accurate transfer of the data.BP: A standardized systemfor internal reporting of GHGsBP, a global energy company, has been collecting GHG data fromthe different parts of its operations since 1997 and has consolidatedits internal reporting processes into one central databasesystem. The responsibility for reporting environmental emissionslies with about 320 individual BP facilities and business departments,which are termed “reporting units.” All reporting units haveto complete a standard Excel pro-forma spreadsheet every quarter,stating actual emissions for the preceding three months andupdates to forecasts for the current year and the next two years. Inaddition, reporting units are asked to account for all significantvariances, including sustainable reductions. The reporting units alluse the same BP GHG Reporting Guidelines “Protocol” (BP, 2000)for quantifying their emissions of carbon dioxide and methane.All pro-forma spreadsheets are e-mailed automatically by thecentral database to the reporting units, and the completed e-mailreturns are uploaded into the database by a corporate team, whocheck the quality of the incoming data. The data are then compiled,by the end of the month following each quarter end, to provide thetotal emission inventory and forecasts for analysis against BP’sGHG target. Finally, the inventory is reviewed by a team of independentexternal auditors to provide assurance on the quality andaccuracy of the data.For internal reporting up to the corporate level, it isrecommended that standardized reporting formatsbe used to ensure that data received from differentbusiness units and facilities is comparable, and thatinternal reporting rules are observed (see BP casestudy). Standardized formats can significantly reducethe risk of errors.G U I D A N C E


Identifying and Calculating GHG EmissionsG U I D A N C EApproaches for rolling upGHG emissions data to corporate levelThere are two basic approaches for gathering data on GHGemissions from a corporation’s facilities (Figure 10):• Centralized: individual facilities report activity/fueluse data (such as quantity of fuel used) to the corporatelevel, where GHG emissions are calculated.• Decentralized: individual facilities collect activity/fueluse data, directly calculate their GHG emissionsusing approved methods, and report this data to thecorporate level.FIGURE 10. Approaches to gathering dataDECENTRALIZED CENTRALIZEDSITE LEVELActivity dataActivity data xemission factor=GHG emissions➡➡CORPORATE LEVELSites report activity data(GHG emissions calculated atcorporate level: activity data xemissions factor = GHG emissions)Sites report GHG emissionsThe difference between these two approaches is in wherethe emissions calculations occur (i.e., where activity datais multiplied by the appropriate emission factors) and inwhat type of quality management procedures must be putin place at each level of the corporation. Facility-levelstaff is generally responsible for initial data collectionunder both approaches.Under both approaches, staff at corporate and lowerlevels of consolidation should take care to identify andexclude any scope 2 or 3 emissions that are alsoaccounted for as scope 1 emissions by other facilities,business units, or companies included in the emissionsinventory consolidation.CENTRALIZED APPROACH:INDIVIDUAL FACILITIES REPORT ACTIVITY/FUEL USE DATAThis approach may be particularly suitable for officebasedorganizations. Requesting that facilities reporttheir activity/fuel use data may be the preferred option if:• The staff at the corporate or division level can calculateemissions data in a straightforward manner onthe basis of activity/fuel use data; andEmissions calculations are standard across a numberof facilities.DECENTRALIZED APPROACH:INDIVIDUAL FACILITIES CALCULATE GHG EMISSIONS DATAAsking facilities to calculate GHG emissions themselveswill help to increase their awareness and understandingof the issue. However, it may also lead to resistance,increased training needs, an increase in calculationerrors, and a greater need for auditing of calculations.Requesting that facilities calculate GHG emissionsthemselves may be the preferred option if:• GHG emission calculations require detailed knowledgeof the kind of equipment being used at facilities;• GHG emission calculation methods vary across anumber of facilities;• Process emissions (in contrast to emissions fromburning fossil fuels) make up an important share oftotal GHG emissions;• Resources are available to train facility staff toconduct these calculations and to audit them;• A user-friendly tool is available to simplify the calculationand reporting task for facility-level staff; or• Local regulations require reporting of GHG emissionsat a facility level.The choice of collection approach depends on the needsand characteristics of the reporting company. Forexample, United Technologies Corporation uses thecentralized approach, leaving the choice of emissionfactors and calculations to corporate staff, while BP usesthe decentralized approach and follows up with audits toensure calculations are correct, documented, and followapproved methods. To maximize accuracy and minimizereporting burdens, some companies use a combination ofthe two approaches. Complex facilities with processemissions calculate their emissions at the facility level,while facilities with uniform emissions from standardsources only report fuel use, electricity consumption, andtravel activity. The corporate database or reporting toolthen calculates total GHG emissions for each of thesestandard activities.The two approaches are not mutually exclusive andshould produce the same result. Thus companiesdesiring a consistency check on facility-level calculationscan follow both approaches and compare theresults. Even when facilities calculate their own GHGemissions, corporate staff may still wish to gatheractivity/fuel use data to double-check calculations andexplore opportunities for emissions reductions. These46CHAPTER 6


CHAPTER 6 Identifying and Calculating GHG Emissions 47data should be available and transparent to staff at allcorporate levels. Corporate staff should also verify thatfacility-reported data are based on well defined, consistent,and approved inventory boundaries, reportingperiods, calculation methodologies, etc.Common guidance on reporting to corporate levelReports from facility level to corporate or divisionoffices should include all relevant information as specifiedin chapter 9. Some reporting categories arecommon to both the centralized and decentralizedapproaches and should be reported by facilities to theircorporate offices. These include:• A brief description of the emission sources• A list and justification of specific exclusion or inclusionof sources• Comparative information from previous years• The reporting period covered• Any trends evident in the data• Progress towards any business targets• A discussion of uncertainties in activity/fuel use oremissions data reported, their likely cause, and recommendationsfor how data can be improved• A description of events and changes that have an impacton reported data (acquisitions, divestitures, closures,technology upgrades, changes of reporting boundariesor calculation methodologies applied, etc.).REPORTING FOR THE CENTRALIZED APPROACHIn addition to the activity/fuel use data and aforementionedcommon categories of reporting data, facilitiesfollowing the centralized approach by reportingactivity/fuel use data to the corporate level should alsoreport the following:• Activity data for freight and passenger transportactivities (e.g., freight transport in tonne-kilometers)• Activity data for process emissions (e.g., tonnes offertilizer produced, tonnes of waste in landfills)• Clear records of any calculations undertaken to deriveactivity/fuel use dataREPORTING FOR THE DECENTRALIZED APPROACHIn addition to the GHG emissions data and aforementionedcommon categories of reporting data, individualfacilities following the decentralized approach byreporting calculated GHG emissions to the corporatelevel should also report the following:• A description of GHG calculation methodologies andany changes made to those methodologies relative toprevious reporting periods• Ratio indicators (see chapter 9)• Details on any data references used for the calculations,in particular information on emission factors used.Clear records of calculations undertaken to deriveemissions data should be kept for any future internal orexternal verification.G U I D A N C E• Local emission factors necessary to translate fuel useand/or electricity consumption into CO 2 emissions.

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