Are Electric Cars Built in a Green Way?

This post, part of a series we're running all about electric cars, was written by Christopher Lampton from HowStuffWorks.com.

n 2006, an Oregon firm called CNW Marketing & Research caused a firestorm in the alternative fuels community when it published a report entitled "Dust to Dust: The Energy Cost of New Vehicles from Concept to Disposal." It purported to analyze the energy efficiency of a car based not just on how many miles it gets per unit of fuel but also on how much energy is used in the manufacture of the car itself and how much energy it takes to get rid of the vehicle once it reaches the end of its lifecycle. Probably the most incendiary finding in the report was that the lifecycle energy cost of a Toyota Prius hybrid was, according to the CNW researchers, greater than that of a Hummer. In other words, the gas-guzzling Hummer was more environmentally friendly –more green – than a hybrid.

Scientific analysis quickly poked holes in a lot of the report's assertions (for a sample, read this Pacific Institute report entitled "[url='http://www.pacinst.org/topics/integrity_of_science/case_studies/hummer_vs_prius.pdf']Hummer versus Prius: 'Dust to Dust' Report Misleads the Media and Public with Bad Science"), but left open questions that there might be hidden energy and resource costs in the manufacture of hybrids and electric cars that could result in more damage to the environment than is the case with cars that have standard internal combustion engines. And if such manufacturing damage exists, it would probably involve the manufacture of the batteries.

All cars have batteries, but the battery in a car with an internal combustion engine is quite small compared to the arrays of battery cells required for hybrids and electric cars, where the battery power needs to be sufficient to run the motor that keeps the car in motion. (In a hybrid, the battery-operated motor only powers the car a portion of the time, but in an electric car the motor, and by extension the battery, is the only thing that keeps the car moving other than sheer inertia.)

The Toyota Prius hybrid uses a battery technology called nickel-metal hydride (NiMH). As the name implies, it's based on the element nickel. Unfortunately, nickel is thought be a carcinogen and the extensive nickel mining necessary for creating the NiMH batteries needed by hybrids has a lot of environmental drawbacks: It's energy intensive, dangerous to the health of the miners, and generates cancer-causing pollution. So the manufacture of NiMH batteries is one aspect of the Prius and other hybrids that is decidedly not green.

The good news is that state-of-the-art electric cars like the Nissan Leaf and plug-in hybrids like the Chevy Volt (which spends most of its time running as a strictly electric car) won't be using nickel-metal hydride batteries at all. Instead, they'll be using lithium-ion (Li-ion) batteries, a technology that is much more environmentally friendly than NiMH. As this Time Magazine article puts it, "[L]ithium mining, as observed in countries with deposits like Chile, Argentina and China, seems to be less hazardous than other kinds of mineral extraction."

Of course, all mining activities have their environmental costs, but there's little question that the mining of lithium for electric cars that use lI-ion batteries is greener than the mining of nickel for cars that use NiMH batteries. (And, for the record, there's no conclusive evidence that a Hummer is even remotely as green as a Prius.)