Davis and Kahn on the effects of used vehicle imports on emissions

Davis, Lucas and Matthew Kahn. 2010. International trade in used vehicles: The environmental consquences of NAFTA. Economic Policy. 58-82.

Davis and Kahn set up a nice little set of models to help us understand what has likely happened in the durable goods market for vehicles. In comparatively higher income countries, used durables like cars are likely to get traded out to lower income countries–here, the US and Mexico. And since older durables emit more than new cars, they find that this robust trade in used vehicles increases lifetime emissions as Mexico consumers substitute away from transit use to used car consumption and those cars stay in use longer. An excellent paper: I highly encourage you to go read (and to spring for membership in the American Economic Association: you get lots of good journals and a calendar with economist centerfolds! One of my happiest investments this year.)

A couple of weak points: they say at the beginning that they establish that trade makes emissions go up in both countries. No, they actually show that emissions go down in the US but up in Mexico, and the increases in Mexico outstrip the reductions in the US. I don’t love the way they calculate emissions: they have to make some assumptions about the distribution of vehicle miles of travel, and I suspect that it is possible, given their analysis, that trade make makes VMT go up in both countries. Moreover, they note that costs of repairs are low in Mexico, yet they really don’t calculate how repairs can significantly improve engine performance. A car isn’t as good as new, but that doesn’t mean it stays a clunker after it’s traded. This may be particularly true depending on where the used car ends up in Mexico: Mexico City has different incentives and regulations for fixing up a car than other parts of the country.

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Watching the maritime emissions controls change

The US EPA has been pursuing Emissions Control Areas with the International Maritime Organization (IMO). Currently, there is a 200 mile ECA for sulfur oxides, particulate matter, and nitrogen oxides. The EPA is looking to expand it:

The latest component of EPA’s coordinated strategy for addressing emissions from ocean-going vessels is a proposal, from August this year, to designate an Emission Control Area for the U.S. Caribbean. The United States submitted a proposal to IMO in advance of the September 2010 IMO meeting, requesting that waters around the coasts of Puerto Rico and the U.S. Virgin Islands be designated as an ECA. Other EPA programs to address harmful emissions in the U.S. include voluntary partnerships under EPA’s Clean Ports USA program and implementation of a Clean Air Act rulemaking that EPA finalized last December.

link: Air Emission Regulation Update

These are pretty significant gains for the EPA, as it allows for the control of emissions just offshore

The other good news:

For the latest Emission Control Area (ECA) initiative for the U.S. Caribbean, EPA estimates that the total costs of improving ship emissions from current performance to ECA standards while operating in the proposed ECA will be approximately $70 million in 2020. The costs to reduce a ton of NOx, SOx and PM are estimated at $500, $1,000 and $10,000, respectively.

link: Air Emission Regulation Update

That’s pretty low-hanging fruit in terms of new regulation or building programs.

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Transit emissions and the importance of ridership

Streetsblog Capitol Hill highlighted a very nice FTA report that tracks urban transit emissions. A pdf of this report appears here.

As I have ranted before here, we have to know ridership in order to make claims about emissions benefits. This graphic, taken from the report, does a good job of showing us this effect. We’d be better off filling up cars on the road than we are running underutilized trains. Now, this is a much different story if we are getting people to use the trains. This is why a reasonable accuracy in ridership forecasts matters. I’m not asking for perfection; I’m asking for an honest assessment of how many people we’re building something for so that we can fairly assess what we are doing here.

The other possible way of changing this figure would be to change the feedstock of the energy sources for all of the vehicles. Cleaning up electricity generation would change the emissions per passenger mile.