Are Hybrids Harmful to the Environment?

One hears and reads a lot of things.  Unfortunately, unlike Canada, the US has no law that reporters and journalists must tell the truth.  That means that they can lie to you (knowingly or unknowingly) and there are no repercussions.  Even a second’s reflection on that should indicate that much of what you read and see… may not be totally accurate.

A fairly recent (2006-2007) report claimed that the Toyota Prius has a higher lifetime energy cost than a Hummer H1 SUV.  The claim covered total energy and carbon dioxide emissions and the conclusion was that hybrids do more damage to the environment than a Hummer.

I have heard this report many times over the last few years (including from Jeremy Clarkson of my favorite show, Top Gear).  So, is this right?  Are hybrids more damaging to the environment?

In a word… no.  All of these ‘journalists’, bloggers, reporters, etc got their information from one report.  Dust to Dust by CNW Research (whoever they are).

But, as we shall see, some of the information in that report is outright wrong.  Some appears to be totally made up.  And no one has actually seen where their data is coming from, how they developed their assumptions, how they calculated anything, or whether anyone has peer-reviewed the report.

Most of this information comes from a brief analysis of the Dust to Dust paper.  Unlike Dust to Dust, this paper publishes the sources of information. 

So, what can be gleaned from the Dust to Dust paper?  Well, the first thing that should be obvious is that the lifetime numbers of cars seem to be totally made up.

Miles and Life cycle

The Hummer H1 is expected to last 379,000 miles over 35 years.  While the Prius is expected to last 109,000 miles over 12 years.  As someone who has driven GM products, that’s complete bull… but OK, let’s go with it.  Why make these assumptions?  When Dust to Dust was written, the Prius hadn’t even been in production for 12 years.  The H1 hummer hadn’t been in production for 35 years.  How do they justify these values?  We don’t know.  They didn’t say.

 The paper also assumes (with no justification) that hybrids will, over the life of the car, drive fewer miles than the same non-hybrid vehicle.  Four hybrid cars were compared with the non-hybrid version of the same vehicle.  The hybrid Honda Accord was assumed to be driven slightly more than 50% of the distance of the non-hybrid Accord.  Why?  We don’t know.

Life cycle Costs

 The Dust to Dust paper’s analysis suggests that the majority of the energy and carbon dioxide is produced during the construction of the vehicle, not the operation.  Just a few seconds thought ought to make one question this.  But, we don’t have to assume this, we can show that it’s not correct. 

  • British research shows that 90% of all energy used in the motor industry goes to vehicle operations (L. Elghali, V. McColl-Grubb, I. Schiavi and P. Griffiths. 2004. “Sustainable resource use in the motor industry: a mass balance approach.” Viridis Report VR6. Transport Research Ltd.). 
  • The British auto trade group estimates that 10% of carbon dioxide emissions is from manufacturing, 5% to disposal of the vehicle, and 85% to operations (The UK Automotive Sector: Toward Sustainability.” 2006. Society of Motor Manufacturers and Traders. 
  • The Center for Sustainable Systems (University of Michigan) conducted a joint project with US automakers and material suppliers.  They analyzed 6 systems, 19 subsystems, 644 parts, and 73 different materials used in manufacturing a vehicle.  The result?  85% of energy is used in operating the vehicle. (Center for Sustainable Systems, University of Michigan. 2005. Personal Transportation Factsheet. Ann Arbor, Michigan (August). See also, Keoleian, G.A., K. Kar, M. Manion, and J. Bulkley. 1997. Industrial Ecology of the Automobile: A Life Cycle Perspective. SAE R-194. Society of Automotive Engineers, Warrendale, PA CSS97-04, and G.A. Keoleian and D.V. Spitzley. 2006. “Life cycle based sustainability metrics.” In M.A. Abraham (editor) Sustainability Science and Engineering: Defining Principles. Elsevier B.V. Amsterdam, pages 132-135.)

I could go, with at least three more studies.  But that’s not the point.  We can see from this that a 60 mile per gallon Prius ought to be much more efficient and environmentally friendly than a 9 mile per gallon Hummer H2.

Same Car Different Data

Here’s a great example of made up data.  The Dust to Dust paper reports two Toyota vehicles; the Scion xA and Scion xB.  These two vehicles are built on the same chassis, with the same engine, in the same factory, using the same materials and processes.  The two cars mass within 25 kilograms of each other. Yet, the paper reports that lifetime of the xA to be 156,000 miles and the xB 189,000 miles.  Why?  No one knows.

Super Accurate Estimates

The “estimate” of the life cycle of the Hummer H1 is 34.96 years.  That’s an accuracy of within 3 days.  Somehow, this report knows, to within 3 days, how long a Hummer H1 will last.

Similarly, the report compares a Mercury Mariner hybrid SUV and a Toyota Highlander hybrid SUV.  The results suggest that the Highlander will last 15 days longer than the Mariner (11.56 years vs. 11.60 years).

 Just for those that don’t know.  When you create averages like this, it becomes harder to become more exact, not easier.  Estimating, or even averaging, the lifetime of a multi-year thing with an accuracy of days cannot be done.  It’s like a oncologist telling someone, “yes, you have cancer.  You will live for another 31 days, dying between 2:10 and 2:13 PM on Saturday the 14th.”  It’s just silly.

There are additional complaints in the Hummer vs. Prius report. 

 I always told my students, “Always ask yourself, ‘does this make sense’, ‘who wrote this and how does he know’, and ‘could I do the same work and get the same results?’” You should always research everything.  I know, most of us don’t have time to research everything.  But some things are critical.  You should research doctors and medicines.  You should research major purchases.  You should research who to vote for.  You also should research things that have an impact not only for you, but for your children and grandchildren.

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