Environmental benefits (or not) of the Cash for Clunkers program

Ideally a program like the Car Allowance Rebate System (CARS) really would cause a reduction in greenhouse gas emissions, improve energy security, reduce oil dependence costs, and increase energy sustainability.  The program’s key is to incentivize replacement of inefficient cars with more efficient transportation choices.  An earlier article (The Cash for Clunkers program) gives an overview of the program.  Let’s now take a closer look at the potential for environmental benefit.

One can make a simple and fairly obvious assertion that a transportation choice requiring less resources is less environmentally bad than other transportation choices.  For example a person with a 60 mile each way daily solo commute in a 10 mile/gallon SUV is causing more environmental harm than if they moved closer to their job and rode a bicycle to work.  While it’s a rather extreme example it does illustrate that everyone has transportation needs, and that different transportation choices have different consequences.  Assuming the environmental harm of burning a gallon of gasoline does not differ much whether it was burned in a 10 mile/gallon SUV or in a 50 mile/gallon efficient car, fulfilling ones transportation needs while burning less fuel causes less environmental harm per mile driven.

Because CARS incentivizes replacing an inefficient four wheeler with a more efficient four wheeler, there is a positive gain.  By being more fuel efficient the new four wheeler will burn less gasoline and cause less environmental harm.  Well, minus several factors.  The owner of the new car may feel emboldened to drive more now that they’re causing less environmental harm per mile of driving.  There is an environmental impact of prematurely destroying an existing vehicle while causing the creation of a new vehicle.  It’s unclear from the CARS website whether one can trade in an older passenger car and replace it with a class 2 truck where the minimum required fuel efficiency is 15 miles/gallon.

The American Council for an Energy-Efficient Economy publishes the Green Book ratings that attempts to account for various emissions and environmental factors that account for the actual emissions from a given vehicle.  It is actually important which vehicle in which the gasoline is burnt.   While fuel efficiency (miles/gallon) is an important determinant of greenness, it does not account for the other factors determining relative emissions (CO, HC, NOx and PM) emitted from each vehicle.

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Because CARS only incentivizes replacing a four wheeler with another four wheeler, the only possible environmental gain is from the higher fuel efficiency.  It’s well known that many transportation choices have higher fuel efficiency than the highest efficiency four wheelers.  Many motorcycles or scooters have fuel efficiency of 100 miles/gallon or more.  There are many electric scooters, motorcycles or bicycles available which have zero tailpipe emissions.  Using mass transit or telecommuting also causes a reduction in individual fuel use.  None of those possible transportation choices receive any incentive through the CARS program.

Under CARS the higher miles/gallon efficiency is a one-time event.  There is nothing in CARS requiring future behavior changes in the new vehicle purchaser.  They may go back to gas guzzlers after participating in the program.  A change which would cause lasting fuel efficiency improvements is to change the CAFE standards.

What’s needed for positive environmental benefit is a long term shift away from inefficient transportation choices.  While the CARS program has a noble intent to incentivize such a shift, the actual benefits appear unclear.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

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  1. Pingback: The Cash for Clunkers program | The Long Tail Pipe

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