"A groundless rumor often covers a lot of ground."
- Anonymous
An old claim has been brought to my attention again. Hybrids pollute more than Hummers because of one component: The battery. Not believable, and definitely not true!
The best tool for debunking rumors like this is Argonne National Lab’s GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) Model. The respected Society of Automotive Engineers dubbed it the “gold standard” model for analyzing vehicles and fuels.
Argonne juxtaposed comparable internal combustion and hybrid cars, and did indeed find that the latter will yield slightly more global warming pollution in the manufacturing process. BUT – production accounts for a mere 10-20% of a vehicle’s lifetime emissions profile. Far more important is 15 years of driving, the average for cars. Take that into account, and you find that a regular car's lifetime emissions are nearly TWICE those of a hybrid.
The “regular car” in this example gets 25 mpg. Since the Hummer is lucky to hit double-digits in mpg its lifetime heat-trapping pollution eclipses the hybrid's.
Thanks to my colleague Luke Tonachel for passing along this analysis, and for adding some points to keep in mind when considering environmental downsides of batteries:
- All cars use batteries and the elements for those batteries, whether lead in conventional vehicles or nickel in today’s hybrids, are mined. Mining is not without environmental problems.
- Lead is more pervasive and therefore more toxic than nickel.
- Nickel batteries, like lead batteries, can be recycled.
- The use of nickel metal hydride batteries enables the hybrid car to exist because lead batteries would be too big and heavy to provide the same performance in a hybrid that they have today.
- Nickel batteries will soon by transitioning to lithium batteries. Lithium batteries can be even more environmentally benign. Lithium is not toxic and lithium batteries can pack more power into each pound of cell than nickel metal hybrid batteries, enabling cars to use more clean electrical energy and less gasoline without weighing down the vehicle further. Some cars in Japan already have lithium batteries and they will likely be in US vehicles in the next couple of years.