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April 05, 2006

Hybrid Whiplash

What to make of this news from the Eugene, OR Register-Guard?

In a report that's sure to be controversial, CNW Marketing Research of Bandon concludes... that, even though hybrid cars use less fuel, they require more energy - and are therefore worse for the environment - than conventional cars because their design and manufacture are more complex and the costs of disposal or recycling are higher for their batteries, electric motors and other specialized components. [Emphasis added.]

Hybrids use more energy than regular cars? Is this real, or just pro-SUV propaganda?

Now, just to be clear, I haven't reviewed the study myself. But the online materials that's CNW's made publicly available seem serious & fair-minded -- not like a cheap hit-job on hybrids, but rather a sober analysis that reaches some unexpected and counterintuitive conclusions.

That said, I think there's very good reason not to take the study too seriously. Not yet -- and not until the authors can answer some tough questions about what their study implies.

CNW does deserve credit for looking at energy costs over a vehicle's entire life cycle--not just what it consumes on the road, but also what it costs to manufacture, distribute, repair, and dispose of a car. But some of their numbers seem, to put it mildly, a little hard to believe.

According to the study's methods, a Honda Civic (not a hybrid, but a regular model) uses only about 30 percent of its life-cycle energy as gasoline. (See here for the chart.) About 10 percent each go to parts, manufacturing, repair, dissassembly, and replacement; and 20 percent go to other energy costs.

Let's say that's reasonably representative of other models -- that is, gasoline accounts for only about 30 percent or thereabouts of the life-cycle energy costs of owning and operating the average car or light truck. But according to the US Energy Information Administration, gasoline consumption accounts for 17 percent of total energy consumption in the US (see here for total consumption, and here for total gasoline). So that would imply that car manufacture, repair, recycling and other energy costs account about 40 percent of the total US energy supply.

Forty percent? That's just plain wrong. The entire US industrial sector only consumes 33 percent of the nation's energy. So the subset devoted to cars has to consume only a fraction of that.

Just so, it seems downright implausible that cars are responsible for some 57 percent of the nation's total energy use (17 percent for gasoline, 40 percent for manufacture, repair, recycling, etc.). Cars use a lot of energy, to be sure -- but I simply can't believe it's that much.

So that means either: the Honda Civic is a vastly atypical car, and uses substantially more manufacturing energy than most other cars; that I've misread the (limited) available data from CNW; or that the study's authors have some explaining to do if they're going to convince me that I should pay much attention to their results.

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Perhaps the energy-intensive parts manufacturing is done abroad?

Posted by: clew | Apr 5, 2006 10:49:50 PM

To be taken seriously, the authors must explain their methodology and assumptions -- until then, this is nothing more than a press release from a marketing firm. Several commentators have wondered if the study's numbers are corrected for sales volumes:


Meanwhile, a Newsday article reports the Union of Concerned Scientists saying something similar to your observation: the study overemphasizes energy used in production and disposal of the vehicles. They say: "An amazing number of red flags come up" when looking at CNW's conclusions.


Posted by: Laurence Aurbach | Apr 5, 2006 11:06:40 PM

While I agree that the study warrants close inspection, it is refreshing to see embedded energy being considered. If the authors did an Odum EMERGY analysis, then they're probably pretty close to right. I don't know of other methodologies that are as encompassing and precise.

This is the reason I love mid '80's diesels. You're still harvesting their original embedded energy.

I have a Jetta that I run from waste vegetable oil that gets over 40 miles per gallon! Depending on how they're driven, most North American hybrids barely beat that.

Remember the order of the four "Rs": "refuse", "reduce" and "re-use" all trump "recycle." Putting an efficient older auto to work is always better than buying a new one!

Posted by: Jan Steinman | Apr 6, 2006 3:40:27 AM

I find that study hard to believe. Toyota does LCA for the Prius, comparing it to the average vehicle in its class:

CO2 output is a decent stand-in for energy use, and you can see in the chart that from an LCA perspective, the Prius uses about 30% less energy than a comparable vehicle.

The color scheme for the chart is as follows:
light blue - raw material production
dark blue - parts/vehicle production
yellow - energy to move the car
green - maintenance
orange - waste

Note how for both the Prius and the conventional vehicle the energy used in actually moving the vehicle is more than 50%. In the case of a conventional vehicle, it seems to be about 75-80%.

Here's the full page where the chart is located:

Posted by: Joseph Willemssen | Apr 6, 2006 8:50:44 AM

Don't miss today's article in the NYTimes comparing the Accord and Camry hybrids.

The article mentions that an 85 lb weight gain pushed the Accord into a different weight class and reduced its EPA mileage rating by 3-4 mpg. How does THAT work? Are the tests different for different weight classes--i.e. different mixes of driving styles?

Posted by: Maarten | Apr 6, 2006 3:35:20 PM

Maarten -
You're right -- that's weird. Thanks for pointing it out.

Posted by: Clark Williams-Derry | Apr 7, 2006 10:26:40 AM

Can someone smarter than me explain how a measure of energy consumed(from any number of sources!) be expressed in dollars? It makes no sense.

Posted by: DC | Apr 8, 2006 3:49:44 AM

DC -
It may be that I just need to write more clearly. When energy geeks talk about energy "costs", they often mean how much energy it takes to do something. So the energy "costs" of recycling a car might include the number of BTUs of energy it takes to collect, transport, disassemble, and reprocess all of the car parts -- energy is used at every step of the way.

Similarly, the energy "costs" of driving include the energy consumed as gasoline, plus (possibly) the costs of extracting the petroleum, refining it into gasoline, and trasnporting it to the pumping station; plus (possibly) the embodied energy of petroleum based lubricants.

Sorry if that wasn't clear.

Posted by: Clark Williams-Derry | Apr 8, 2006 9:21:45 PM