In 2014 the author issued a report comparing energy intensities of flying and driving from 1970 through 2010 (Sivak, 2014). (Energy intensity is the amount of energy needed to transport one person a given distance.) The main finding of that study was that, while flying domestically in the U.S. used to be much more energy intensive than driving, that is no longer the case. Indeed, in 2010–the last year examined in that study–the energy intensity of driving was shown to be 57% greater than the energy intensity of flying. The present study extends the analysis through 2012. Furthermore, this study corrects the publically available flying data for two inconsistencies: (1) the estimates of the energy intensity of flying are based on different carrier groups for fuel consumed and passenger miles flown, and (2) the estimates of the energy intensity of flying include cargo operations (paid freight and mail). The variable of interest was BTU per person mile. For flying, “person mile” refers to passenger mile, while for driving it refers to occupant mile. For flying, only domestic operations were considered (RITA, 2015a). For driving, all light-duty vehicles (cars, SUVs, pickups, and vans) were included; the data were calculated from the information in RITA (2015b). According to two footnotes in RITA (2015a), the derivation of the energy intensity of flying was based on four carrier groups for passenger miles flown (majors, nationals, large regionals, and medium regionals), but only three groups for fuel consumed (without medium regionals). Given that data on fuel consumed by medium regionals only are not available, the inconsistency was resolved by subtracting the 2 passenger miles flown by medium regionals from the published total for all four groups. Thus, in the present calculations, both components of energy intensity (fuel consumed and passenger miles flown) were based on the same three groups (majors, nationals, and large regionals). (This correction proved not to be of major significance, because medium regionals currently represent less than 1% of passenger miles flown.) According to a footnote in RITA (2015a), the published data on energy intensity of flying was based on fuel consumed for both passenger and cargo operations. In other words, fuel consumed included fuel needed to transport paid freight and mail on passenger carriers and on all-cargo carriers. Therefore, in this study, the published data for energy intensities of flying were corrected for the proportion of revenue ton miles that were represented by revenue passenger ton miles only (i.e., not including revenue freight ton miles and revenue mail ton miles). These calculations were performed for the majors, nationals, and large regionals. (Author/publisher)
Samenvatting