Globe

THE GLOBAL WARMING PUZZLE:
HOW MANY PEOPLE DOES ONE CAR AMOUNT TO?

By Victor Miguel Ponce

          Globe


  1. A world average of individual car usage is about 12,334 miles per year, which translates into (12,334 miles / 365 days) = 33.8 miles per day, or 54.4 kilometers per day.

  2. A world average of gasoline mileage per car is 31.2 miles per gallon, which translates into 50.2 kilometers per gallon, or 13.2 kilometers per liter.

  3. Thus, the world average daily consumption of gasoline is:   (54.4 km/day) / (13.2 km/liter) = 4.12 liters per day per car.

  4. The average density of gasoline is 0.74 kilogram per liter.

  5. The world average daily consumption of gasoline is:   4.12 liters per day per car × 0.74 kilogram per liter = 3.05 kilograms per day per car, or 3,050 grams per day per car.

  6. The average energy released by the burning of gasoline is 45.8 kilojoules per gram, or 10.95 kilocalories per gram.

  7. The average global rate of gasoline energy consumption is:   (3,050 grams/day × 10.95 kilocalories per gram) = 33,398 kilocalories per day per car.

  8. An average person weighs 62 kilograms.

  9. To maintain his/her own weight, an average person needs 33 kilocalories per kilogram.

  10. Thus, a constant-weight average person consumes (62 kilograms × 33 kilocalories/kilogram) = 2,046 kilocalories per day.

  11. Thus, the ratio of car-to-person energy consumption is:   (33,398 / 2,046) = 16.3

  12. In summary, in terms of energy consumption, one (1) car is equivalent to approximately 16.2 persons.

  13. There are approximately 7,124,000,000 people in the world today (November 2013).

  14. There are approximately 1,015,000,000 cars (including commercial motor vehicles) in the world today (2013).

  15. The people in the world burn (7,124,000,000 × 2,046 kilocalories/day) = 14,575,000,000,000 kilocalories per day = 14,575 teracalories per day.

  16. The cars in the world burn (1,015,000,000 × 33,398 kilocalories per day) = 33,899,000,000,000 kilocalories per day = 33,899 teracalories per day.

  17. The total number of calories consumed daily by people and cars amounts to 48,474 teracalories.

  18. This is equivalent to (48,474,000,000,000 kilocalories per day / 2,046 kilocalories/day/person) = 23,692,000,000 equivalent persons.

  19. The ratio between equivalent persons and actual persons is: (23,692,000,000 / 7,124,000,000) = 3.3

  20. Thus, current use of fossil fuel [in car transportation] amounts to an equivalent population which is about 3.3 times larger than the actual value, in terms of energy consumption and subsequent release of carbon dioxide to the atmosphere.

  21. A hypothetical doubling of the number of cars, to 2,000,000,000, would raise the equivalent population to about six (6) times larger than the actual number, the later ratio expressed in terms of current world population.

Note:   Values in items 1, 2, 4, 6, 8, 9, 13, and 14 are estimated averages, intended for reference only. Actual calculation will vary with usage or growth.


Victor Miguel Ponce is professor of civil and environmental engineering at San Diego State University. His specialty is hydrology, environmental science, and sustainable development.

http://carsandpeople.sdsu.edu
Count
© 2007, 2013 Victor M. Ponce 131117