Sunday, December 28, 2008

Can we sustain our dependence on personal cars?

previously published in the Terre Haute Tribune Star, 12/28/2008

I’ve owned 12 cars. I expect to have a couple more before I’m finished. Whether people are willing to admit it or not, cars are more than just a means of transportation. Were cars just transportation, then we would not have so many colors, so many types, so many brands, and so many options. Cars are an extension of our living rooms, a status symbol, and part of our identity.

Are personal cars as the primary means of transportation for Americans, “sustainable?” I admit, up front, that I hope the answer is yes.

“Sustainability” is not such a new idea, though it is getting increased attention these days. The most widely used definition of sustainability is the one used by the UN, adopted in 1983: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”

It is easy to show the “irrationality” of relying on personal cars as the primary mode of transportation in the US or anywhere else. The current system is not sustainable as the recent flirtation with $5 gasoline showed us. Two key American values, convenience and freedom, are likely to make any radical change very difficult. Cars embody both of these values, perhaps more than any other product does (cell phones an exception). Cars give us the convenience and freedom to move about when and where we want. Never mind the incredible expense, both personally and socially, of this method of transportation. Automobile accidents kill about 40,000 to 50,000 Americans every year. Personal cars led to dependence on foreign oil and warps foreign policy in a way that nothing else does. All this and more in the name of convenience and the freedom to go 0-60mph in under ten seconds.

It doesn’t seem possible that we are going to sustain personal cars without some changes. Dependence on foreign (expensive) oil is what has our attention this time. We didn’t learn much from the 1973 oil embargo. Less than 10 years after that we were buying SUVs (stupid useless vehicles). The real threat to sustaining our love affair with cars is global warming. About half of carbon emissions come from our tailpipes.

According to figures compiled by the Sightline Institute (, a single rider in an SUV is the worst contributor to tailpipe born greenhouse gases, 1.6lbs of CO2 per passenger mile. Carpooling with one other person reduces that figure almost in half (the extra passenger is not carbon free but the increase is very small). The two person SUV contributes about the same amount as a local transit bus ¼ full. A solo rider in a passenger car contributes about 1.2lbs of CO2 per passenger mile. Adding one car pooler brings the contribution down to about that of a Prius (Toyota’s electric-gas hybrid vehicle) with a solo driver.

Based on this, the solution is to reduce greenhouse emissions from our cars by just switching to hybrid vehicles. We could get even more reduction with the next generation of hybrid vehicle, the plug-in hybrid. This vehicle stores enough energy to run the car without the gas motor for between 20 to 50 miles. An oft cited statistic from a 1990 US Dept of Transportation study, is that 70% of Americans drive less than 33 miles per day. I wonder if that statistic is still true today, but even if the daily drive has increased to 50 miles, that is still a lot of miles covered without emitting carbon from our tailpipes.

The plug-in hybrid has a “long tailpipe,” however. The energy to run it is coming from electric generating plants. As we move toward more and more wind and solar energy, that long tailpipe becomes less of a concern. How fast are we moving?

Electric cars are not as convenient as our current cars. Think of how many times you forget to charge up your cell phone. A day without your cell phone is different than a day without your car or the amount of gas used due to forgetting to plug the car in.

Based on my and my wife’s daily drives, a plug-in hybrid would work for us. Based on the life cycle of our cars, assuming a suitable model is available, we could buy one in the next two years and the second one in four to five years. If that is average, is that fast enough to reduce carbon emissions to a sustainable level? Across the world? Unfortunately, I doubt it.

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