Meteor Blades posted a story on Cash for Clunkers, suggesting that we make it long term. There's a big plea for environmental friendliness there, and I truly appreciate that sentiment.
The problem is a plan to use CARS to help the environment doesn't seem that compelling. I don't mean to call him out, but the numbers don't suggest to me that what he says will really help. I'd like to run you through some statistics and show why I'm not convinced.
(Just to clarify, I support CARS as an economic measure; I just don't believe it's worth much environmentally.)
Warning: numbers are frequently and heavily rounded. This is not intended to be rigorous.
According to the Department of Transportation, there are around 136 million cars on the road. That excludes trucks and buses, so it's basically the total pool of cars that could conceivably be traded in. This is the baseline for how much impact a cash for clunkers program can have. The absolute total, including buses and trucks, is 250 million vehicles.
I also looked up the US fuel consumption. We use 820 million gallons of raw petroleum a day, of which 378 million is motor gasoline, stuff that could actually feed cars. 71% of all petroleum is used for transportation; that's 582 million gallons. If 100% of motor gasoline goes to cars, that leaves around 204 million gallons of other types of fuel being burned for transportation purposes. Based on detailed statistics, we can assume that all the other transportation petroleum is jet fuel and distillate fuel oil (trucks, ships, buses, anything else diesel). It doesn't quite add up but it's close enough for the time being.
Quick recap: around two thirds of burnt transport petroleum is used by cars. The rest are diesel or jets or ships, none of which are particularly clean burners, I don't think. Let's move on.
Let's round off Cash for Clunkers as being a $5000 credit, and imagine we set aside $25 billion for the program. So far, $3 billion has been approved, so this would represent a massive expansion in the program. That $25 billion could help fund five million new cars. Slightly under 3.7% of the cars in the country would be replaced with vastly more fuel efficient models. How much more fuel efficient? Let's say the trade in average is 16 mpg and the new average is 32 mpg. True these are made up, but they are at least reasonable I think. Let's even assume that, thanks to better engine and exhaust technology, the emissions of those new vehicles are zero.
Since those 3.7% are now consuming half the fuel they used and emitting none of the pollution, we've managed to cut the total fuel consumption of all cars by 1.8% and emissions by 3.7%. That's 1.2% of all transport petroleum and, if we assume all emissions rates to be the same, 2.4% of total transport emissions. As a broadly round baseline, let's simply say that overall petroleum consumption and overall emissions are decreased by 2%. This is about 11.5 million gallons per day, as the result of what I think is an overly optimistic, if not completely unrealistic, estimate.
The total effect on our transportation petroleum consumption is that it goes from 582 million gallons a day to 570 million gallons a day. That's not nothing, but considering it's the theoretical result of a massively expanded CARS program which people take advantage of at high rates, I'm not sure how much we've gained.
And then there's one last, tricky little detail. How much gasoline does it take to destroy and process five million old clunkers, and then build five million new cars AND send them across the country to dealerships? If this expansion takes five years, then that's 2700 cars arriving at dealerships every single day. Parts have to be moved around from all over the world, more so than ever for advanced cars like the Prius that use quite a few semi-exotic materials.
I support CARS as an economic initiative, but as an environmental one? I just don't see it. Now, Meteor's proposals are a little better thought out and more complex than CARS as it currently stands, of course. Expanding other budgets to match is a good idea. Changing attitudes is a good idea. Destroying old cars makes no sense. But if you're strictly targeting replacement of fuel guzzling cars, the environment isn't gaining much. It's just losing slightly less -- hopefully.
[Quick note: I wrote this diary before reading the end of Meteor's post properly. I don't intend to criticize his suggestions, just offer a look at what kind of numbers we're dealing with.]
Update: Meteor Blades responded. My numbers are based on the current version of CARS, which is in fact substantially different from Meteor Blades' proposal. One key point -- linking the credit amount directly to the MPG of the new car, which biases the whole thing towards far higher gains in efficiency. That's how it should've been handled in the first place.