SAGE » Q&AQ: How much of an environmental problem will the batteries in alternative fuel cars create? Are they really a sound environmental alternative?
Asked by Lynnae Thandiwe, '84, Atlanta, Ga.
Unlike with gas and diesel cars, the good environmental karma from an electric vehicle grows the more you use it. Though production of an electric vehicle is more resource-intensive than the production of an internal combustion vehicle, with each mile driven, the internal combustion vehicle loses its environmental edge. Electric vehicles—battery included—have a lower environmental impact over their full lifetimes.
A Note on Analysis Ambiguity
Distilling the wealth of possible environmental impacts from a battery or entire vehicle into a single number for comparison is a complicated process lacking a clear methodology. Each study attempts to account for this potential ambiguity through the use of different analysis methods, focusing on metrics like resource depletion or energy use and greenhouse gas emissions. But we don't want to pick environmental favorite—we like conserving resources and limiting greenhouse gas emissions. Further compounding the ambiguity can be the range of the data inputs. The Essential Answer referenced the most conservative calculation method reporting the highest impacts, just ensure accuracy in our conclusion.
Another layer of ambiguity lies in the source of the electricity. Different methods of producing electricity vary in their environmental footprint, with coal the most carbon-intensive and renewable sources, such as wind, the least. MIT conducted a study in 2007 that evaluated lifecycle greenhouse gas emissions of current and future vehicles. As shown in Figure 3, accounting for projected technology gains, electric vehicles using coal-supplied power are expected to emit more greenhouse gas than their conventional internal combustion counterparts by 2035. Switch the electricity source to natural gas or an average mix of power, however, and electric vehicles remain more environmentally friendly.
Battery Lifetime
It may come as a surprise that the battery plays a relatively small role in the total impact of an electric vehicle. The primary difference in production of these different types of vehicles is the battery, though, so where is this difference impact coming from? To trace the environmental effects, let's follow the creation of a lithium-ion battery, the type generally used in electric vehicles.
The first step—mining lithium carbonate to produce the ingredient that enables the battery's rechargeable characteristics—is the one that garners the most press for environmental harm. In fact, the lithium extraction accounts for less than 3 percent of the battery's entire environmental burden—a number partly attributable to the fact that just 0.007 percent of the battery's weight is lithium. Further, the process used to extract lithium from salt water in South America has a low energy demand. The disposal of lithium doesn't seem to be a big problem, either, as the federal government classifies lithium-ion batteries as non-hazardous waste fit for the normal waste system.
The next step—the production of the anode and cathode (the parts of the battery through which current flows)—is the most environmentally burdensome step. Accounting for about 60 percent of the impact, this step requires mining and other energy-intensive procedures to refine and mold the metals. The mining of the aluminum and copper necessary for these components is responsible for about half of the battery's total environmental impact. Mining aluminum is an involved process that starts with retrieving ore deposits from underground. Then, several chemical reactions are necessary to separate pure aluminum from the other minerals. Copper mining is still more complex, requiring the additional step of concentrating ores, since they start with only a small percentage of copper.
Building the battery pack and assembling the finished product are the last steps. The sourcing of steel, cables and the wiring board for the battery pack is responsible for about one-fifth of the total environmental impact.
If we are looking to easily reduce the impact of battery production, the battery lifetime sketch presents some bad news. Because each step of the battery production process has its own fair share of the impact, targeting only one would not be particularly effective. As discussed in the Essential Answer, however, our best bet to reduce EV's impacts lies in battery recycling.
Battery Recycling Case Studies
In the United States, the reuse and recycling of electric car batteries has yet to reach widespread popularity. There are, however, several international cases where the technology is being developed and tested.
American battery producer EnerDel and Japanese corporation ITOCHU announced in January 2010 their joint effort to develop and produce battery systems for a residential energy grid storage system. The system, to be installed in a major apartment building near Tokyo, will connect electric vehicle charging to providing homes with electricity—infrastructure that will be necessary if batteries are to be used for storage. Japanese corporations Nissan and Sumitomo are taking the next step and collaborating on a joint venture to recycle lithium-ion batteries from electric vehicles to store the energy generated from photovoltaic solar panels.
Domestically, Better Place also has exciting battery repurposing ideas and is developing a battery switch system. The system, in which electric vehicle users could drive to Better Place stations to have their batteries switched out in a matter of minutes, would eliminate the need to recharge and enable used batteries to be used in short-trip vehicles. What's more, Better Place's battery switching could save the consumer—and hazardous waste system—money by offering customers 80 percent capacity batteries at a discounted rate.
These technology initiatives, coupled with increasingly strict battery recycling regulation in the European Union as well as a projected growth in electric vehicle infrastructure, provide an optimistic outlook on recycling and repurposing batteries.
In addition to repurposing batteries for use in the electric grid, the massive storage potential of car batteries provides incredible opportunity for energy-starved locations. Renting charged batteries already contributes energy in developing nations that lack an extensive electrical grid. There are, however, downsides of the current system: many batteries now in place are lead-acid, which are not only corrosive, but also have a lower capacity than lithium-ion. Additionally, electricity delivered this way is expensive, averaging about 70 cents/kWh (more than triple what I pay) and heavy to carry long distances. The incorporation of lighter weight lithium ion batteries into this system would allow for increased electricity usage at a lower cost and hassle, a feat that could possibly help drive development.
Whether here in the United States or around the world, the electric vehicle story is an optimistic one. The appearance of reasonably priced, family-appropriate models is encouraging to the average consumer interested in a reduced-guilt, zero to 60 in just a few seconds, joyride. The prospect of being able to further reduce impact by recycling the battery just sweetens the pot. Keep an eye on the road, because electricity is not just for buildings anymore.
