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Friday, October 5, 2007

Dear Science Podcast: How Green Are Hybrids?

posted by on October 5 at 12:04 PM

Hybrid Highlander

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APOCALYPSE-smaller.jpg

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Tree Canopy


In this week’s Dear Science podcast.

RSS icon Comments

1

Hybrid SUVs make me want to kill.

Posted by Fnarf | October 5, 2007 12:46 PM
2

Once you started talking Charles' tree fetish I turned it off.

It seems a little silly to be name dropping Newton in the argument. It's not like there is a shortage of energy or momentum in the universe; if you can power a car efficiently (e.g., by prayer) the weight of the car is not a major issue anymore (things like sprawl can be addressed through policy).

Dr. Science's revealed his inconsistancy, in my opinion, when he brought in flying (can't believe I listened that far). If you fly from Seattle to NYC, round trip, twice a year that is the equivalent of driving 12,000 miles, or about 33 a day. So if there are people commuting 16 miles to work each way, but don't fly to NYC twice a year, they are doing about as well as you, so criticizing driving from that place seems more about aesthetic than real science.

Next time you should get two people who actually disagree!

Posted by Jude Fawley | October 5, 2007 1:11 PM
3

You'd probably sound more credible if you understood that hybrids benefit from running the gas engine at a more efficient RPM, not just capturing braking energy.

Also if you'd explain why you think trains are efficient enough for you but the 25% increase in efficiency from hybrids is not good enough. Especially since the shorter lifespans of cars allows you to take advantage of new technology more readily than long-lived trains (balanced against the manufacturing costs).

And then there is the issue of progress: Today's hybrid cars are a test platform for more efficient technology of the future. They don't have to be ideal; only an improvement that gets us closer to where we want to be.

You're speaking outside your field, aren't you? The things you say remind me of the astronomer Fred Hoyle deciding the biologists were wrong about evolution.

Posted by elenchos | October 5, 2007 6:59 PM
4

@3

There is one point that I probably didn't make clear enough in the podcast: the difference between an absolute and relative improvement. The 25% relative improvement I cited was for an absolute increase from 40 to 50 mpg. The baseline is already pretty good for a small car (weight more than the propulsion matters). In other words, it's hard to beat a liquid fueled internal combustion engine for overall efficiency--especially when accounting for the manufacturing and recycling environmental impact.

And yes, I am speaking out of my field. Modern science is about specialization, right? I'm already a little broad in what I follow and study--stem cell biology, cardiovascular biology, virology, aspects of immunology to name a few. I struggle with the breadth of questions I receive for the column. My solution so far is to stick with the broadest consensus (carefully researched by reading a decent amount of literature as well as asking experts I know) when speaking out of my field. In this example, I believe my stance is little different than you'd get from most automotive or mechanical engineers. Still, do you have suggestions how I could be better? (The comparison with Fred Hoyle smarts, btw.)

@2.
I really was a shitty devils advocate, wasn't I? This should give you an aneurysm: I'm flying to Europe tomorrow, for a scientific conference. I'd rather contribute my carbon for tasks like this (where no viable alternative exists) rather than trips to the QFC. Still, I should buy some trees when I return.

Posted by Jonathan Golob | October 5, 2007 8:14 PM
5

JG, as a health professional who has attended many a conference, I'm doubtful that the trip is worth the carbon dioxide emitted (both by the planes and the speakers), but I hope the research you present can help someone, sometime... As far as aneurysms, I really don't care where you fly - we all use rationalizations to justify our lifestyle of choice; I just don't think your argument against hybrids and driving in general makes sense. (By the way, posing the "flying to a conference vs. driving to a QFC" contrast is called, especially in the social sciences, a "straw man argument")

Posted by Jude Fawley | October 5, 2007 9:06 PM
6

I think you should do your best to refrain from trying to support your argument just by saying "it's scientific; I'm a scientist so believe me." If anything, you should be encouraging the opposite, precisely because it's so hard to know all the facts, or to pose the question well. Ask people to really weigh the evidence you have to offer rather than just accept your conclusion because you're an authority.

I don't think it was totally unreasonable to take the question "Should I get a hybrid?" and turn it into "How efficient are hybrids compared to other options?" The first question is debatable on many levels, and probably requires a lot of assumptions before you can get anywhere. So it had to be changed, and even narrowed down more to only consider a few physics aspects: how much mass you have, how much energy is used.

It would be more helpful and interesting to not try to make strong claims, and instead talk about the need to narrow down and simplify the question. You have to do that, or else get caught up in intractable debates such as all the pros and cons of the road and transit levy. Which is to say, "science doesn't have an answer for every question, but here are some answers to smaller questions science can answer."

Just saying, "well trains are efficient, bikes are efficient" are nice pat answers, and probably what people are looking for when they want to get a "scientific" opinion. But they shouldn't be allowed off the hook that easily.

Posted by elenchos | October 5, 2007 9:27 PM
7

Elenchos,

Those are excellent points. Thank you. I'm not sure if you've read my carbon credits column where I tried an approach more like you suggest in # 6. Of course, I promptly received a (polite) e-mail complaining that I hadn't *really* answered the question.

If you have time, write this critique of my, and others, science writing as a question to dearscience@thestranger.com and I'll wrap it into a future column.

Posted by Jonathan Golob | October 5, 2007 9:39 PM
8

Hey, what about me?! :(

Posted by Jude Fawley | October 6, 2007 6:11 AM
9

(Just kidding!)

Posted by Jude Fawley | October 6, 2007 6:27 AM
10

Plug in hybrids get 100 or more MPG.

And around here that electricity is not just cheaper (1/10 the cost of gas) but it's renewable. 99 percent (or at my house 100 percent).

Now that's green.

Posted by Will in Fremont | October 7, 2007 4:35 AM
11

Any discussion of hybrids should not only take into account that the combustion engine is (most of the time, except at high speeds) running at a more efficient RPM, but also the environmental cost of storing electrical energy in batteries.

Having to scrap the batteries after the car's end-of-life also incurs environmental damage.

MPG-wise hybrids are better than the same car as a non-hybrid, but environmentally?

Posted by w00t | October 7, 2007 9:01 AM

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