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EIA Annual Energy Outlook explores implications of behavior and demographics on light-duty vehicle energy demand

Light-duty VMT is beginning to decouple from traditional drivers. Source: EIA. economic Click to enlarge.

The US Energy Information Administration (EIA) is in the process of staging the release of the full Annual Energy Outlook 2014 (AEO2014), its annual report on projected energy use and analysis of select energy topics. The roll-out began on 7 April and will conclude on 30 April. Included in AEO2014 is a set of eight “Issues in Focus” articles, exploring topics of special significance, including changes in assumptions and recent developments in technologies for energy production and consumption.

The most recent of these In Focus articles explores the impact of demographics and behavior on light-duty vehicle (LDV) energy demand. LDVs accounted for 61% of all transportation energy consumption in the United States in 2012—8.4 million barrels of of oil equivalent per day—and represented nearly 10% of world petroleum liquids consumption. LDV energy use is driven by both LDV fuel economy and travel behavior, as measured by vehicle miles traveled (VMT). LDV VMT per licensed driver peaked in 2007 at 12,900 miles per year and has since decreased to 12,500 miles in 2012.

The shift in VMT highlights the importance of travel behavior and its influence on LDV energy consumption. Before the 2007 peak, travel behavior in the United States tracked closely with economic growth. Since 2007, trends in US LDV travel have not followed the trends in economic indicators such as income and employment as closely. Although economic factors continue to influence travel demand, demographic, technological, social, and environmental factors also have shown the potential to affect LDV travel.

—Hutchins and Maples

The Reference case in AEO2014 assumes that VMT per licensed driver begins to increase after 2018. The compound annual rate of growth in total VMT for LDVs from 2012 to 2040 in this case is 0.9%—below the 1.7% rate from 1995 to 2005 but higher than the 0.7% average annual growth rate from 2005 through 2012. AEO2014 also includes Low and High VMT cases.

  • The Low VMT case assumes an environment in which travel choices made by drivers result in lower demand for personal vehicle travel, consistent with the recent trend. In the Low VMT case, total US LDV travel demand in 2040 is 19% lower than in the Reference case with annual increase in total LDV VMT from 2012 through 2040 averaging only 0.2%.

    In the Low VMT case, US LDVs consume 18% less than in the Reference case: i.e., 5.3 million barrels of oil equivalent per day in 2040. This results in total transportation sector CO2 emissions roughly 9% lower than in the Reference case.

  • The High VMT case assumes changes in travel behavior that result in an increase in VMT per licensed driver compared with the Reference case. In the High VMT case, total US LDV travel demand in 2040 is nearly 6% higher than in the Reference case—an annual increase in total LDV VMT from 2012 through 2040 averaging 1.1%.

    In the High VMT case, LDVs consume 5% more than in the Reference case—i.e., 6.7 million barrels of oil equivalent per day in 2040,—resulting in total transportation sector CO2 emissions more than 2% higher than in the Reference case.

LDV energy use in the three AEO2014 cases. Click to enlarge.   LDV CO2 emissions in the three AEO2014 cases. Click to enlarge.

Factors influencing VMT. Travel demand depends on economic, demographic, technological, social, and environmental factors, the EIA analysts noted. In general, they suggested, demand for LDV travel is likely to decline when licensing rates fall; use of telework increases; or fuel prices are relatively high. On the other hand, fuel use by LDVs is likely to rise when the driving-age population grows; during periods of expanding economic activity; or when fuel prices are relatively low.

Despite the data showing a recent decoupling of travel from economic indicators, there are still strong links between economic activity, employment and commuting. When the labor force participation rate declines, retirees and people having difficulty finding jobs may reduce their travel as compared with people who have similar demographic profiles and are employed. When labor force participation rates rise, VMT per driver is likely to increase, particularly for millennials (those born between the early 1980s and early 2000s).

Income, fuel prices, the costs of purchasing a vehicle, and other vehicle operating costs also all influence the extent to which an individual can afford LDV travel. While all these economic factors play a significant role, demographic factors such as population, age distribution, and licensing rates also are important determinants of LDV travel demand, the EIA report says. Population age groups have different gender distributions, licensing rates, and travel behaviors. As the age groups change over time, long-term effects on VMT will become apparent, particularly for the age groups that have the greatest influence on VMT.

  • Since 1990, licensing rates generally have been declining for the two youngest age groups and increasing for the two oldest groups. For males, most age groups have seen declining or stagnant licensing rates, with the only exception being males 65 years and older. The female age groups have seen similar stagnation for most of the younger age groups and an increase for females 65 years and older.

  • Since about 1990, the average age of males who are licensed drivers has been higher than the average age of the male population 16 years and older (the male driving population). That trend is projected to continue as fewer young males obtain licenses or delay obtaining licenses until later in life. Conversely, the average age of female licensed drivers has been lower than the average age of the female driving population, but it is projected to be higher than the average age before 2020 and to continue rising through 2040. For both males and females, the average age of the driving population and average age of licensed drivers increase in the Reference case, with fewer younger individuals obtaining licenses and more choosing to wait until later in life to become licensed drivers.

  • The population age 34 years and below has seen a decrease in both licensing rates and VMT per licensed driver, with the licensing rate for the group falling by 5% over the past decade.

  • Since 2000, VMT per licensed driver for the population under 20 has dropped by 13%. In 1990, 52% of eligible individuals under 20, and 92% of those between 20 and 34 years of age, obtained their licenses. In 2010, those shares were 43% and 86%, respectively. If the trend persists, licensing rates could continue to decline or flatten out for the youngest driving populations, further reducing VMT per capita. If the licensing rate returns to historic levels, total VMT will increase.

  • The peak driving age group, between 35 and 54 years of age, has experienced a small decline in licensing, from 95% in 1990 to an estimated 92% in 2010. Drivers in this age group traveled an average of almost 15,000 miles annually in 2012, the highest rate of VMT per licensed driver for any age group. This relatively large age group, accounting for 34% of the population in 2012, has a limited influence on changes in total VMT, because neither the licensing rate nor the share of the population has changed drastically through history or is projected to change significantly in the future. Much of that stability results from high employment rates for this age group, as a result of the interaction between economic and demographic factors.

  • The overall population share in the oldest age group, 65 years and older, has grown steadily since 2000 and is expected to reach 24% of the total population ages 16 and above in 2025, up from a 17% share in 2012. Although the size of this segment of the population has grown since 2000, personal travel (VMT per capita) by the oldest age group dropped by 7% between 2008 and 2009, and its total VMT dropped by 10%. More members of the older population are obtaining their licenses than in the past, but they also have altered their travel behavior, increasing their use of public transportation by 40% during the period from 2001 to 2009.

Demographic changes can also interact with other factors to influence VMT, the report says. Technological, social, and environmental factors also can influence VMT.

  • Alternative modes of travel affect VMT to the degree that the population has access to substitutes for personal LDVs.

  • The increasing fuel efficiency of LDVs can influence personal travel by lowering the marginal cost of driving per mile. As vehicle efficiency improves, individuals can drive the same distance with less fuel and therefore at a lower cost, which may result in an increase in VMT.

  • Telecommuting, e-commerce, urbanization, and social media can supplant or complement personal vehicle use.

Spatial development patterns may also begin to play a different role in determining VMT than is suggested by history, as suburban sprawl gives way to other development patterns.

VMT sensitivity analysis. The High and Low VMT cases suggest possible future changes in travel behavior and their potential impacts on VMT and on LDV energy demand.

  • The Low VMT case assumes a 0.5% annual decrease in VMT per licensed driver from 2013 to 2040 for each age and gender group. VMT per licensed driver for all drivers decline throughout the projection, to about 10,400 miles per year in 2040—a 19% decrease from 12,800 miles per year in 2040 in the Reference case.

    Total LDV VMT increase only slightly in the Low VMT case, to almost 2.8 trillion miles in 2040.

  • The High VMT case assumes a pattern of annual increases in VMT per licensed driver: 0.3% starting in 2013, 0.4% starting in 2016, 0.5% starting in 2019, and 0.6% starting in 2023, slowing to 0.5% starting in 2027, 0.4% starting in 2032, and 0.3% from 2036 through 2040. VMT per licensed driver for all drivers rise to 13,500 miles per year in 2040.

    Total LDV VMT increase to 3.6 trillion miles in 2040 in the High VMT case.


  • Patricia Hutchins and John Maples (2014) “Light-duty vehicle energy demand: demographics and travel behavior” Issues in Focus, AEO2014 DOE/EIA-0383(2014)


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