Transportation Energy Costs

The average car on the road consumed 4,700 British thermal units (BTUs) per vehicle mile in 2015, which is almost a 50 percent reduction from 1973, when Americans drove some of the gas-guzzliest cars in history. The average light truck (meaning pick ups, full-sized vans, and SUVs) used about 6,250 BTUs per vehicle mile in 2015, which is also about half what it was in the early 1970s.

Click on the above image to download a 10.2-MB PDF of the above report. Use links below to download spreadsheets or individual chapters from the report.

By comparison, the average transit bus used 15 percent more BTUs per vehicle mile in 2015 than transit buses did in 1970. Since bus occupancies have declined, BTUs per passenger mile have risen by 63 percent since 1970. While buses once used only about half as much energy per passenger mile as cars, they now use about a third more.

These numbers are from table 2.15 in the latest Transportation Energy Data Book, which has energy consumption data for various forms of transportation through 2015. Table 2.16 reveals that the energy consumed by airlines per passenger mile has declined by more than 75 percent since 1970, so now it is more energy efficient to fly than to drive (at least, if your car is carrying the average 1.55 occupants).

The same table reports that rail transit uses slightly more energy per passenger mile today than it did in 1970. However, the rail numbers in the table must be read with caution: a footnote warns that “Only end-use energy was counted for electricity. Previous editions included primary energy use for electricity which included generation and distribution losses.” Generation and distribution losses are about 67 percent of electrical energy, so the BTUs in the table must be tripled to get the actual amount of energy consumed to move people by electric transit.

The numbers are also a problem for Amtrak, as about a third of Amtrak passenger miles are carried on electric-powered (as opposed to Diesel-electric) trains. The previous edition of the data book indicated that Amtrak used 2,186 BTUs per passenger mile in 2014, while the latest edition “corrects” this to 1,641. In other words, Amtrak really requires about a third more energy than is shown in the data book. That still makes it slightly more efficient than flying, but not much. I suspect that, if the numbers were broken down by route, a few heavily used routes would be energy-efficient while most of the rest would not.

The authors of the data book offer no explanation for why they changed from counting electrical energy from total to end-use. It would be like saying that the average gasoline engine is only about 35 percent efficient, as the other 65 percent is lost as heat, so therefore we’re only going to count the 35 percent of gasoline used to actually move the vehicles. This is a bewildering and disappointing change as it greatly understates energy consumption required for electric-powered transportation.

Update: In an email, one of the book’s authors explained that they decided it wasn’t appropriate to count the “upstream” costs of electrical energy if they didn’t also count the energy costs of locating and extracting fossil fuels. In other words, the data book is not an attempt at doing a life-cycle analysis. My response is that the electrical grid is a closed system and all the costs within that system need to be counted just as they would be if the vehicles themselves were generating the electricity (such as in a hybrid car).

Another problem with the data book is that table 2.16 combines light and heavy rail in the rail transit numbers, which is sort of like combining minivans with full-sized buses. Fortunately, this edition has supplemental figures 2.07 and 2.08 showing BTUs per passenger mile of individual light- and heavy-rail lines. Remember to triple all of the numbers to get actual energy consumed.

One other important piece of information is missing from the data book. The tables show BTUs per vehicle mile for cars, light trucks, and transit buses, and BTUs per passenger mile for cars, transit, planes, and Amtrak. But no table shows BTUs per passenger mile for light trucks.

To convert vehicle miles to passenger miles, the book’s authors used average passenger car occupancies of 1.55 people per car, which is from the 2009 National Household Travel Survey. Average light truck occupancies are higher, so to convert BTUs per vehicle mile to BTUs per passenger mile, divide the former by 1.72. The result is about 3,600 BTUs, which is 20 percent more than cars but still 10 percent less than transit buses.


5 thoughts on “Transportation Energy Costs

  1. paul

    Having bought a 2017 Prius that really is getting 50-52 mpg it now seems ridiculous to drive any non hybrid vehicle. The car has very good safety reviews and weighs over 3,000 lbs weigh with good power and excellent reliability. A much better option than the pretense of public transport to cost effectively reduce CO2 production and imported oil. It appears all major auto makers are developing electric cars and hybrids. That is the future.

  2. LazyReader

    It seems environmentalists continue to confuse energy for electricity in debates. Energy is the ability to perform work, electricity is a form of energy in the form of flowing electrons. Only 39% of the US’ energy is electrically based. That’s 61% carried out by thermodynamic or chemical processes. A gallon of gasoline contains 120 megajoules of potential energy and the US uses 392 million gallons of gas per day (cars, trucks, gas powered equipment, light planes, etc). The US uses 47 Petajoules (47,000,000,000,000,000) of gasoline energy per day. The Wind power industry in the US produces 5.9 Petajoules of energy per day. So even if we convert the US automotive fleet or everything that runs on gas over to electric we’d require at least 47 petajoules of additional electric power (since the current electric supply is occupied by it’s current uses) of additional wind energy or 8 TIMES As many wind turbines that currently dot the country, just to power the automotive fleet. Even Bill gates admitted if you took every battery ever manufactured EVER and wired them up together, Fully charged, you could run human civilization for about 5-10 minutes.

    Before coal became widely available, wood was used not just for heating homes nostalgically but all year long. It was also the principal fuel for industrial processes for virtually all manufactured goods; it was the predominant energy source for humanity. Even if half the land surface of Britain had been covered with woodland we could have made 1.25 million tonnes of bar iron a year (a fraction of current consumption) and nothing else. Even with a much lower population than today’s, manufactured goods in the land-based economy were the preserve of the elite. Deep green energy production – decentralised, based on the products of the land – is far more damaging to humanity than nuclear meltdown. If Europe shuts down their nuclear plants it will not be water, wind or sun, but fossil fuel and imported wood chips to run their industrial society. It’s THAT or reverting back to a pre-industrial society. On every measure (climate change, mining impact, local pollution, industrial injury and death, even radioactive discharges) coal is 100 times worse than nuclear power and Forest depletion doesn’t do much to help the atmosphere either. So nuclear is what were gonna have to endorse. Nuclear’s biggest advantage besides the fact it doesn’t atmospherically pollute. A kilowatt-hour worth of coal fired electricity produces about 2.07 lbs of CO2 or over a million tons per terawatt-hour. The nuclear plant in my home state produces 14.9 Terawatt-hours per year; preventing over 15 million tons of CO2 per year or over half a billion tons over the last 40 years. The US nuclear industry keeps 830 million tons of CO2 out of the air annually. The other thing is the power density and 24/7 reliability a Nuclear reactor takes up a few acres of land and on it’s size produces about 10-20 terawatt-hours per year; a wind farm capable of that much would cover 170,000 acres or 250,000 acre solar farm. Were 7 billion people; were gonna be 9 billion by 2050 and they’re moving to cities from the villages. The world is now half cities; it’s 50% urban, up from 14% in 1900, it’s gonna be 60% urban people by 2030; it’s gonna be 80% urban by 2050 that’s 7 BILLION people living in cities and meeting their energy needs with combustion of wood products which they did in villages……is not a wise or environmentally friendly future. A appetite for city living means 24/7 power demand And they cant rely on combustion for heating, cooking, light and transportation they’ll need electric power and that’s either gonna come from COAL or Nuclear. It’s not coming from renewables despite what they claim; if New York City had to be renewable powered 100% a Wind farm would cover all of New England, fortunately the states gets 13% of it’s energy from the Atom. WEATHER PERMITTING they work. why waste renewable resources by turning them into electricity? Why not use them to provide energy directly? To answer this question, look at what happened in Britain before the industrial revolution. They dammed up all their major rivers…and it was ecologically devastating.
    Traction was intimately linked with starvation. The more land that was set aside for feeding draft animals for industry and transport, the less was available for feeding humans. It was the 17th-century equivalent of today’s biofuels crisis. The same applied to heating fuel. As EA Wrigley points out in his book Energy and the English Industrial Revolution, the 11 million tonnes of coal mined in England in 1800 produced as much energy as 11 million acres of woodland would have generated.

  3. TCS

    Why would U.S. transit buses use more BTU per mile today vs. 45 years ago? How could they have possibly become less efficient in the face of almost a half century of technological progress? Are they operated on appreciably different duty cycles? Have unladen transit buses become significantly heavier? Have American transit bus passengers packed on the pounds? Inquiring minds want to know!

  4. Frank

    “Why would U.S. transit buses use more BTU per mile today vs. 45 years ago?”

    The obesity epidemic. People are enormous now, especially those low-income types who use food stamps to buy soda, candy, and donuts and then sit around most of the day doing nothing. They should walk to the grocery store, but they take the bus instead. Because they are too fat and lazy to walk.

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