Shui Bin, Heather Orr, and Thomas Sanquist, Pacific Northwest National Laboratory, Hadi Dowlatabadi, University of British Columbia

Transcription

1 Total Energy Use and Related CO 2 Emssons of Amercan Household Consumpton, - Shu Bn, Heather Orr, and Thomas Sanqust, Pacfc Northwest Natonal Laboratory, Had Dowlatabad, Unversty of Brtsh Columba ABSTRACT The energy and carbon quantfcaton of U.S. household consumpton s an mportant research subject of the human dmenson of global change. Ths paper studes how U.S. household consumpton contrbuted to natonal and global energy use and related carbon emssons from to. The results clearly reveal that (1) U.S. household consumpton was a domnant drvng force of energy use and related carbon emssons at both natonal and global scales durng the study perod; and (2) annual growth rates of energy use and carbon emssons of U.S. household consumpton were much hgher than offcal statstcs ndcated. Ths paper suggests that a consumpton-based accountng framework, n an open consumptonorented economy, could serve as an mportant alternatve to the exstng producton-based energy and carbon accountng framework for better reportng, analyzng, and helpng mtgate natonal and regonal energy use and related carbon emssons. Introducton The energy and carbon quantfcaton of U.S. household consumpton s an mportant research subject of the human dmenson of global change, consderng that (1) the Unted States contrbutes sgnfcantly to global economc development, energy use and related carbon emssons; (2) the U.S. household lfestyle, wth ts admrers, followers and crtcs worldwde, has long been a subject for sustanablty; and (3) the well-documented data provde unque nformaton support for data analyss, methodology development and polcy studes. Quantfcaton of total energy use and related carbon emssons of U.S. households wll not only nform U.S. households of ther role n resource management and clmate change, but also help polcy decson makers better target key consumpton actvtes and consumer segments. Quantfcaton studes of U.S. household consumpton can be traced back to the late 197s and 198s, when there was an ncreasng research and polcy nterest n household energy use n the wake of the ol crss. Herendeens and Tankaka (1976) studed the Consumer Expendture Survey (CES) , and evaluated emprcally the relatonshp between household expendtures and total resultng energy requrements. Schpper et. al. (1989) dscussed the role of consumer lfestyles n energy use, and concluded that: about 45 55% of total energy use s nfluenced by consumers actvtes for personal transportaton, personal servces, and homes. In the late 199s and s, there was a seres of country studes on energy and carbon quantfcaton of household consumpton actvtes n developed economes, such as Australa (Lenzen ; Lenzen et al. ), Germany and other European countres (Weber and Perrels ; Renders et al. ; Druckman and Jackson 29). Shu and Dowlatabad () 7-31

2 quantfed energy and carbon profles of U.S. household consumpton n and suggested that more than 8% of the energy used and the CO 2 emtted n the U.S. are a consequence of consumer demands and the economc actvtes to support these demands. Recently, the research communty has extended these dscussons to nclude the role of nternatonal trade and the development of quantfcaton methodologes. Ghertner and Frpp () studed the amount of envronmental mpacts from U.S. consumpton that leaked from the current, producton-based accountng durng to. Ther study revealed that n ths leakage 1 exceed[ed] 1% for all studed mpacts, exceed[ed] 2% for GWP, energy, and most crtera ar pollutants, and exceed[ed] 8% for lead emssons and toxcs. Weber and Matthews (28) conducted a thorough account of the sgnfcance of nternatonal trade n quantfyng the global and dstrbutonal aspects of U.S. household carbon footprnt. Ther study ndcated that about 3% of total U.S. household CO 2 mpact n occurred outsde the U.S. They also ponted out that the carbon footprnts of U.S. household consumpton vary sgnfcantly by household ncome. Ths paper, based on an earler paper whch ntroduced total consumer mpacts (TCI) assessment methodology, provdes an updated TCI assessment on energy use and related carbon emssons from U.S. household consumpton from to. Secton 2 revsts key concepts and methodology of the TCI approach, followed by a tme-seres quantfcaton analyss n Secton 3. Polcy mplcatons and conclusons are presented n Sectons 4 and 5, respectvely. Key Concepts and Methodology Key Concepts The TCI approach was developed n recognton of the relatve magntude of drect energy use classfed under resdental consumpton compared to the ndrect mpacts of household consumpton. Ths approach uses the exstng statstcs of household consumpton actvtes to develop a more complete pcture of household level mpacts on energy use and ts externaltes (Shu and Dowlatabad ). The TCI categorzes household consumpton actvtes nto two groups: drect vs. ndrect mpacts. Drect mpacts refer to fossl fuel use and related CO 2 emssons durng the use of a product or a servce by the consumer(s). Indrect mpacts refer to the energy beng used and CO 2 beng emtted before the use of a product or servce. The ndrect mpacts are emboded n the process of the resource explotaton, producton, and delvery process. Household consumpton actvtes whch lead to drect mpacts nclude home energy use and personal travel. Household consumpton actvtes whch lead to ndrect mpacts nclude housng operaton (e.g., shelter and furnture), transportaton operaton (e.g., vehcles), food, apparel, health care, entertanment and others. Table 1 presents the categorzaton of household consumpton actvtes and a smple comparson to the exstng, producton-based sectoral approach. 1 Carbon leakage refers to amount of carbon emssons emboded n mported products and servces whch are not accounted by the exstng carbon accountng framework for the mport country

3 Drect Impacts Indrect Impacts Home Energy Use Personal Travel Housng Operaton Transportaton Operaton Food and Beverage Apparel Table 1 Categorzaton of Drect and Indrect Impacts Comparsons wth the The Categorzaton of TCI Producton-based Sectoral Approach space heatng Health Care Entertanment and Readng Others ar condtonng water heatng energy use by applances cars personal trucks ar travel others (water, publc, on demand) housng constructon, producton and transportaton of applances, household furnshng, etc. producton of vehcle purchase (net), producton of gasolne and motor ol, other vehcle expenses, etc. food at home, food away from home men and boys clothes, women and grls clothes, footwear, etc. health nsurance, prescrptons, etc. fees and admssons, magaznes, etc. educaton, tobacco, etc. Resdental sector A subset of the transportaton sector A subset of commercal, ndustral and transportaton sectors. Methodology Home energy use of drect mpacts. The Resdental Energy Consumpton Survey (RECS), a natonal household energy survey conducted by the U.S. Energy Informaton Admnstraton (EIA) every three years, provded home end use data (space heatng, ar condtonng, water heatng, lghtng and applances) n the years of, and. EIA also provded statstcs of home energy use by total and fuel type from to. The TCI estmates on home energy use and related carbon emssons were based on the statstcs above, wth nterpolaton and extrapolaton for the years not provded. Personal travel of drect mpacts. The Transportaton Energy Data Book (TEDB), developed by Oak Rdge Natonal Laboratory, provded aggregated energy estmates by personal transportaton means, such as car, personal trucks, ar travel, water, tax, publc transportaton, and tax (Davs et al. 21).The TCI estmates of personal travel were based on the statstcs above. Indrect mpacts. The estmates of ndrect mpacts of household consumpton are based on the annual CES provded by the U.S. Census Bureau, and the Envronmental Input-Output Lfecycle Analyss (EIO-LCA) model developed by the Green Desgn Insttute at Carnege Mellon Unversty (Carnege Mellon Unversty Green Desgn Insttute 29). The ndrect mpacts of ths study employed the EIOLCA nput-output ndustral benchmark model. Notce that the 7-312

4 consumpton expendture categores of the CES are not a one-to-one match to the 48 commodty categores n the EIO-LCA. Data mappng has been conducted by translatng each of the consumer expendture categores to approprate commodty categores defned by the nputoutput tables. CPI j X p, CES j, T j, p j CPI j, = Where: IndrectEn ergy = EI X ) X p, ($) s a household s expendture n a year on products or servces p n the EIO-LCA; CES j, ($) s the consumer expendture on product j n a year ; CPI j and CPI j, are the consumer prce ndces n n year for a product or servce j; T jp s the transformaton matrx of consumer expendture category j to an ndustral product or a servce category p; IndrectEnergy(EJ) s annual energy consumpton of ndrect nfluences n the Unted States; IndrectCO2(Mt) s the annual CO 2 emssons of ndrect nfluences n Unted States; p refers to an ndustral product or a servce n a year, where = to ; j refers to a CES expendture category; EI p (thousand J/$) s the energy ntensty of ndustral output or a servce p. CI p (thousand J/$) s the carbon ntensty of ndustral output or a servce p. Uncertantes p ( p p, IndrectCO = ( CI X ) 2 p p, p EIOLCA. EIO-LCA analyses are based on surveys of expendture n the economy. These reflect the prce pad by each ndustry for nputs to ts producton process. Ths approach s excellent n provdng an economy-wde measure of energy, materal and labor nputs and externaltes from economc actvty. However, the specfcs of any partcular product are subject to sgnfcant uncertanty. These uncertantes arse from two factors: (1) the data have been collected at an aggregate level of economc actvty rarely processed at a fner scale than 5 dentfers; (2) the models are based on average expendtures on nputs. There can be sgnfcant varaton n prces for products (dependng on ther attrbutes) wthn most partcular product category. For example, shoes can be $15/pr or $15/pr. Wthn the EIOLCA framework, the analyses are based on the average cost of products and the average of nputs to and externaltes assocated wth ther producton. Ths makes EIOLCA an excellent tool for an economy-wde assessment of resource nputs and externaltes, even capable of trackng technologcal and relatve prce changes at the aggregate scale. However, EIOLCAs are not suted to analyss of a specfc product s mx of nputs and envronmental mpacts f t uses nputs that are very dfferent n prce to the average or a product whose prce s atypcal of that sector

5 Internatonal trade. Ths TCI study does not explctly quantfy the contrbuton of nternatonal trade to U.S. household consumpton. Ths smplfcaton, however, seems to produce a smlar result as Weber and Matthews 28 paper, whch calculated the contrbuton of exports from the top seven trade partners (Canada, Chna, Germany, Japan, Mexco, Unted Kngdom. and Korea) to the U.S. household carbon footprnt (HCF) through the nput-output tables of these seven trade partners. Ther HCF paper presented two estmates of U.S. household carbon footprnts n, 4,693 Mt usng weghted CES data and 6,694 Mt usng nput-output expendture data. The estmated CO 2 emssons presented n ths TCI study for the same study year was 4,876 Mt, 3.9% hgher than the CES estmates of the HCF paper. It may be explaned that offset of energy and carbon embodment may be ncurred between the Unted States and ts top trade partners. Chna, wth more carbon-ntensve fuel structure than the Unted States, holds the largest trade defct wth the Unted States. However, the total exports of Canada, Germany, Japan and Mexco have hgher aggregated exports to the Unted States compared to Chna over the study perod 2, and these countres have cleaner fuel structures than the Unted States. Ths study does not account for ar, sea, and ral transportaton outsde of the Unted States. Others. The TCI estmates nhert all uncertantes from the aggregated data provded by dfferent data sources such as RECS, TEDB, and CES. Besdes EIOLCA, there are uncertantes assocated wth an nput-output analyss, such as (1) the aggregaton of household consumpton categores based on the household consumpton categores defned by CES and the correspondng match to the ndustral categores defned by the producton categorzaton of nput-output tables, and (2) assumptons on homogenety and temporal dscrepances (Wedmann 29) Results and Dscusson A Sgnfcant Drvng Force at the Natonal Level Total energy use and related CO 2 emssons from U.S. household consumpton had ncreased from 64.3 EJ and 4,39 Mt n to 8.4 EJ and 5,84 Mt n, respectvely, wth an annual growth rate of 2.3%. Durng the same perod, drect mpacts (the purple lnes wth sold squares n Fgure 1) had hgher energy use and related carbon emssons than ndrect mpacts (the purple lnes wth empty squares), but the gap between them decreased over years. In, drect mpacts were assocated wth 41.3 EJ energy use (compared to 38.9 EJ from ndrect mpacts) and 2,58 Mt CO 2 emssons (compared to 2,546 Mt from ndrect mpacts). Indrect mpacts, however, grew much faster than drect mpacts, wth annual growth rates of 3.1 vs. 1.5% for energy use, and 3.2 vs. 2.3% for carbon emssons. 2 For example, n, exports from Chna to the U.S. were bllon U.S. dollars, whle the total of Canada (313.1), Mexco (21.8), Japan (145.5), and Germany (94.4) was nearly bllon U.S. dollars

6 Drect mpacts. Home energy use (22.3 EJ and 1,249 Mt n ) and personal travel (19.1 EJ and 1,289 Mt n ), two drect mpacts, had hgher total energy use and related CO 2 emssons than the top three household actvtes of ndrect mpacts (housng operaton, transportaton operaton and food) n Fgure 1. Fgure 1 Energy Use and CO 2 Emssons of U.S. Household Consumpton, Drect Impacts (D) Annual Energy Use (PJ) Annual Carbon Emssons (Mt) Indrect Impacts (ID) Home Energy Use (D) Personal Travel (D) Housng Operaton (ID) Transportaton Operaton (ID) Food (ID) Wthn home energy use, applances (1.4 EJ and 59 Mt n ) and space heatng (4.9 EJ and 269 Mt n ) were the top two end uses, followed by water heatng and ar condtonng. Between and, ar condtonng and space heatng had the fastest growth (8.9%) and declne (-2.8%) rates, respectvely, among all household actvtes under both drect and ndrect mpacts (Fgure 2). Cars (9.7 EJ and 654 Mt n ) and personal trucks (6.7 EJ and 448 Mt n ) were the top two end uses n personal travel. The growth rate of personal trucks (e.g., SUV) took off n and then leveled off begnnng n, wth an overall 4.5% annual growth rate, the second hghest among all categores. Energy use and related carbon emssons from ar travel and other travel modes (categorzed as Others n Fgure 2) plunged n, reflectng the sharp reducton n travel followng the September 11 attack. Although ar travel slowly bounced back n, t began decreasng agan n, largely due to the rsng prce of fuel. Indrect mpacts. Housng operaton (15.3 EJ and 1,5 Mt n ), transportaton operaton (1.4 EJ and 681 Mt n ) and food consumpton (6.3 EJ and 654 Mt n ) were the top three categores of ndrect energy use and related carbon emssons (Fgure 2). Transportaton operaton and entertanment were the fastest growng categores of ndrect mpacts durng the study perod, wth 4.1 and 4.6% respectvely

7 Fgure 2 Energy Use and Related CO 2 Emssons by Household Consumpton Category and Annual Growth Rate, - 16 Drect Impacts - Home Energy Use 16 Drect Impacts - Personal Travel 16 Indrect Impacts EJ Growth Rate 2.5 Growth Rate 2.5 Growth Rate Index (=1.) Applance SpaceHeatng Water Heatng Ar Condtonng Cars Personal trucks Ar Others Housng Transportaton Food Apparel and servce Others Entertanment Health care The Sgnfcance of U.S. Household Consumpton at the Global Level Durng the study perod, U.S. household consumpton was a domnant drvng force not only at the natonal level but also at the global level. Our estmates suggest that U.S. household consumpton contrbuted 16-17% of global energy use and 18-2% of global CO 2 emssons, respectvely. Accordng to the exstng producton-based accountng framework, the Unted States, Chna, Russa, Inda and Japan were the top fve countres wth the hghest natonal energy consumpton and related carbon emssons between and, represented by the dotted lnes n Fgure 3 (U.S. Energy Informaton Admnstraton 21). The energy use and related carbon emssons from U.S. household consumpton, TCI estmates, are represented by the red sold lnes. In terms of contrbuton magntude, energy use and related CO 2 emssons from U.S. household consumpton was a consstently sgnfcant drvng force at the global level, outpacng the other four top countres untl t was surpassed by Chna n n terms of CO 2 emssons and n for fnal energy use

8 Fgure 3 Energy Use and Related CO 2 Emssons of U.S. Household Consumpton and Top Fve Global Energy Consumers and Carbon Emtters energy use n PJ metrc ton of CO2 emssons Unted States (Total, Sectoral) Amercan Household (Total, CLA) Chna Russa Inda Japan Polcy Implcatons U.S. Household Consumpton as an Important Polcy and Research Subject The sgnfcant contrbuton of U.S. household consumpton to natonal and global energy use and related CO 2 emssons suggests that U.S. household consumpton s a relevant and sgnfcant target for polcy and research at both scales, wth the ablty to nform serous actons to mprove energy effcency and mtgate carbon emssons. Related polcy mplcatons and dscussons could nclude the followng: Drect mpacts. Home energy use and personal travel are target consumpton actvtes for U.S. households n terms of ther shares of total household energy use and related CO 2 emssons. These two consumpton actvtes are where households have more drect control (such as use frequences, purchase of energy-effcent applances and cars, and fuel choces) compared to household actvtes wth ndrect mpacts. Energy and fuel effcency standards. Energy use of ar condtonng and personal trucks (e.g., SUV) had the hghest annual growth rates among all categores, 8.9 vs. 4.9% (see Appendx 1). Ths hghlghts the mportance of developng stronger energy effcency standards for ar condtonng and fuel effcency standards for personal trucks. Land-use polcy and urban desgn. Accordng to the TCI estmates, household daly moblty (cars and personal trucks) accounted for 86% of energy use for personal travel and 4% of drect energy use n. Besdes the development and promoton of advanced fuel standards s not the only soluton, an ntegrated consderaton of land-use polcy and urban desgn (a compact 7-317

9 cty regardng locatons between offce buldngs, resdences, schools, and shoppng malls), and the development of a publc transportaton system could be consdered as an ntegrated urban plan to reduce energy use of personal travel. Many of the polcy topcs mentoned above have been analyzed and dscussed. The TCI analyss helps to dentfy the target actvtes that not only have hgher mpacts on energy use and related carbon emssons, but also n whch households are the key stakeholders and decson makers n the polcy and project development related to energy effcency, technology development, land use and urban desgn (Shu and Dowlatabad ). An Alternatve Perspectve from the Consumpton-based Approach to the Sectoral Approach The current sectoral and producton-based approach s wdely employed as the standard natonal reportng framework to account energy consumpton and carbon emssons (Eggleston et al. ). Ths approach often groups human consumpton actvtes nto admnstratve sectors such as ndustral, transportaton, commercal and resdental (U.S. Energy Informaton Admnstraton 21). As the default energy and carbon accountng system at the regonal and natonal levels, the sectoral approach s gven substantal admnstratve support for data collecton and polcy research, n order to better serve natonal and regonal polcy makers. Emergng consumpton-based approaches often are composed of a wde range of household consumpton categores and reflect energy use and related carbon emssons from the perspectve of household consumpton. The dfferences between the consumpton-based and producton-based accountng frameworks provde dfferent perspectves when evaluatng natonal and regonal energy consumpton and carbon emssons. For example, the energy and carbon estmates based on the sectoral approach ndcated that ndustral and transportaton sectors are the largest two energy user and carbon emtters n the Unted States whle resdental sector (or home energy use) only ranks the thrd. The TCI estmates, based on a consumpton-based accountng approach, clearly suggested that the household sector s the largest energy user and carbon emtter n the Unted States. Another example, the producton-based annual growth of total energy consumpton n the Unted States. (the dashed red lne n Fgure 4) grew far more slowly than the annual growth of GDP and populaton durng the same perod (the sold blue and purple lnes, respectvely). However, the consumpton-based estmate (the sold red lne) shows a much hgher growth rate for U.S. household consumpton than total U.S. energy use and populaton growth. Ths ndcates that the growth of U.S. households contrbuton to global energy consumpton s not only hgher than the country s populaton growth but also much faster than the growth level often clamed and wdely perceved

10 Fgure 4 Annual Growth Rate of Energy Use of U.S. Household Consumpton: The TCI vs. the Sectoral Approach, Index (=1) Total Energy (Sectoral) Total Energy (CLA) GDP Populaton The two examples above suggest that a consumpton-based accountng framework could serve as an mportant alternatve to the exstng producton-based accountng framework. Concluson U.S. household consumpton s a sgnfcant drvng force behnd energy use and related carbon emssons at both the natonal and global scales. Ths study reveals that total energy use and related CO 2 emssons of U.S. household consumpton ranged from 64.4 EJ to 8.2 EJ and 4,266 Mt to 5,369 Mt from to, whch accounted for 16-17% of global energy use and 18-2% of global CO 2 emssons durng the same perod, wth much hgher annual growth rates than the offcal, producton-based statstcs ndcated. Quantfyng household consumpton s an mportant research subject of human dmensons of global change. It helps reveal crtcal nformaton on energy consumpton and related carbon emssons of human consumpton actvtes, whch have been overlooked or cannot be fully reflected by the exstng producton-based sectoral accountng approach. Quantfcaton of total energy use and related carbon emssons of U.S. households wll not only nform U.S. households of ther roles n resources management and clmate change, but also help polcy decson makers better target key consumpton actvtes. In an open consumpton-orented economy, a consumpton-based accountng framework, such as TCI, can serve as an mportant alternatve to quantfy, analyze, and mtgate natonal and regonal energy use and carbon emssons. Acknowledgements Ths research s supported by the Department of Energy Contract DE-AC5-76RL183. Rebecca Schaaf and Alson Delgado kndly provded edtoral assstance for ths paper. Authors would lke to thank Steve Smth at Jont Global Change Research Insttute, Chrstopher Payne at Lawrence Berkeley Natonal Laboratory and two anonymous revewers for ther nsghtful comments

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