By Can Mao
Nowadays, it is a known fact that automobiles have a major impact upon the environment, either based on official report authorities such as United States Environmental Protection Agency (US EPA) [1], or industrial association such as Electric Drive Transportation Association (EDTA) [2], or various other independent academic research sources [3][4]. Just to give you some idea, the US produces about 10% of the worlds petroleum each year. However, US also consumes about 26% of the world's total production, leading to the dependency on imported crude oil. As history shows, many past or current international geopolitical issues are caused or at least complicated by lack of sustainable and reliable petroleum sources, including the recent the recent BP oil leak incident, which in US has once again put the concern for the long-debated offshore oil drilling back in limelight.
However, what all these have to do with you and me? Or anyone around you and me? A lot. While, I am almost certain that gas or gas price is one of the most popular every topics where two complete strangers may easily break the ice by sharing the impact on their lives from the gas price. It is everywhere in our life, like air, water, and sunshine. According to US Department of Energy (US DOE) [6], the use of energy per year for transportation in US has reached total 30% and it is still going up as indicated in Figure 1 Left. Meanwhile, the percentage in use of petroleum in transportation is closing to 15% as indicated in Figure 1 Right.
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| Fig. 1: Left,US use of energy per year by sectors; Right: US use of petroleum by sectors [5] |
To further break down, as described in Transportation Energy Data Book published by US Department of Energy [6], automobiles and light trucks make up a 59% of the total transportation energy use, where automobiles takes 34% and light trucks 25%.
Obviously, without even thinking about the impact on the environment caused by excessive exhaust from automobiles, it is already very tempting to make the automobile more energy efficient to cut down the overall energy consumption. Another example, assume an average refill of a compact car requires 10 gallon in the gas station. The refill takes about 2 minutes. This implies an energy flow of 10 gallon petroleum/2min, which is approximately 0.25kg petroleum/sec. Since 1kg petroleum produces 44 Mega Joule of energy, in other words, one refill of 10 gallon petroleum at the gas station is equivalent to 11 Mega Watts. Now, go take a look at your household monthly electricity bill and then come back say: WOW!
References
[2] Electric Drive Transportation Association, http://www.electricdrive.org
[3] Otmar Bitsche and Guenter Gutmann, “Systems for Hybrid Cars,”Journal of Power Source, 127 (2004), pp. 8-15.
[4] Joseph Roman, “The car and fuel of the future,” Energy Policy, 34 (2006), pp. 2609-2614.
[5] Internal Combustion Engines, MIT Open Course, http://ocw.mit.edu
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