THE GLOBAL WARMING PUZZLE: HOW MANY PEOPLE DOES ONE CAR AMOUNT TO? By Victor Miguel Ponce           A world average of individual car usage is about 12,000 miles per year, which translates into (12,000 miles / 365 days) = 32.9 miles per day, or 53 kilometers per day. A world average of gasoline mileage per car is 25 miles per gallon, which translates into 40 kilometers per gallon, or 10.4 kilometers per liter. Thus, the world average daily consumption of gasoline is:   (53 km/day) / (10.4 km/liter) = 5.1 liters per day. The average density of gasoline is 0.737 kilogram per liter. The world average daily consumption of gasoline is:   5.1 liters per day × 0.737 kilogram per liter = 3.8 kilograms per day, or 3,800 grams per day. The average energy released by the burning of gasoline is 45 kilojoules per gram, or 10.75 kilocalories per gram. The average global rate of gasoline energy consumption is:   (3,800 grams/day × 10.75 kilocalories per gram) = 40,850 kilocalories per day. An average person weighs 70 kilograms. To maintain his/her own weight, an average person needs 33 kilocalories per kilogram. Thus, a constant-weight average person consumes (70 kilograms × 33 kilocalories/kilogram) = 2,310 kilocalories per day. Thus, the ratio of car-to-person energy consumption is:   (40,850 / 2,310) = 17.7. In summary, in terms of energy consumption, one (1) car is equivalent to approximately 18 persons. There are approximately 6,500,000,000 people in the world today (2007). There are approximately 850,000,000 cars (including commercial motor vehicles) in the world today (2007). The people in the world burn (6,500,000,000 × 2,310 kilocalories/day) = 15,015,000,000,000 kilocalories per day = 15,015 teracalories per day. The cars in the world burn (850,000,000 × 40,850 kilocalories per day) = 34,722,000,000,000 kilocalories per day = 34,722 teracalories per day. The total number of calories consumed daily by people and cars amounts to 49,737 teracalories. This is equivalent to (49,737,000,000,000 kilocalories per day / 2,310 kilocalories/day/person) = 21,531,000,000 equivalent persons. The ratio between equivalent persons and actual persons is: (21,531,000,000 / 6,500,000,000) = 3.31 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. A hypothetical doubling of the number of cars, to 1,700,000,000, 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.

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© 2007 Victor M. Ponce

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