In a briefing last week General Motors reaffirmed their commitment to the launch of the Chevy Volt by late 2010. The primary purpose of this briefing was to discuss the benefits of lithium battery technology as well as the reasons for their choice of LG Chem to produce the first generation of batteries for the Volt. Several points are worth noting:
GM is completing what will be the largest automotive battery lab in the U.S., and they intend to maintain in-house manufacturing capacity to integrate the battery cells into modules and complete battery systems. This gives GM more flexibility to choose cell suppliers for their 2nd and 3rd generation extended range electric vehicles, and lets them have complete control over how the battery interacts with the power management system of the vehicle. The fact GM is keeping 100% of the battery integration in-house illustrates the centrality of the battery in electric vehicles.
Another interesting point made was the reusability of the battery cells. Apparently these batteries, which are designed to last the life of the vehicle, can be reprocessed and recycled for use in a new battery in a new vehicle. One question not answered during this briefing was whether or not lithium resources globally are sufficient to supply these batteries for a global automotive fleet. So we did some digging:
According to a 2006 study by William Tahil of Meridian International Resource entitled “The Trouble With Lithium,” there are 13.4 million tons of lithium extractable from various raw minerals, primarily lithium carbonate. According to R. Keith Evans, in a March 2008 study entitled “Lithium Abundance – World Lithium Reserves,” there are 28.4 million tons of lithium extractable from known reserves worldwide. In the Wikipedia entry on Lithium, 30.0 million tons of lithium are apparently currently available.
post resumes below image
Lithium ingots with a thin layer of black oxide tarnish
To determine how many vehicles these varying quantities of lithium reserves might supply with battery material, it is necessary to determine how many kilograms of lithium are required per kilowatt-hour of storage, as well as how many kilowatt-hours the average electric vehicle’s battery will require.
According to Tahil’s report, about .3 kg of lithium are required per kWh of battery storage. In an interesting 2009 battery discussion on Seeking Alpha, it is noted that about .26 kg of lithium are required per kWh or storage. In terms of kWh required per vehicle, it depends – the Volt, which is an extended range electric vehicle (containing an onboard gasoline powered generator to supply additional electricity to the motor), only requires a 16 kWh battery. The Tesla Roadster, by contrast, has no backup power system, and requires a 53 kWh battery. Given the Tesla Roadster is a lightweight, two seat vehicle, a larger EV without backup power might require an even larger battery, or live with shorter range. Complicating this further is the possibility of battery swapping stations, meaning that for every EV on the road, a supply of available charged batteries will also need to be present.
Nonetheless, interesting conclusions can be drawn using these various figures. Assume there are 20 million tons of lithium that can be extracted from known reserves, and assume, based on a mixture of extended range EVs requiring smaller batteries alongside EVs depending purely on larger batteries – i.e., assume an average battery storage per EV of 30 kilowatt-hours. Finally, assume .275 kilograms of lithium are required for each kilowatt-hour of storage. If you run these numbers, it appears we can build 2.42 billion EVs before we run out of known lithium reserves.
Not only is this a reassuring calculation for those of us who are enthusiastic about the electrification of the automobile, but it is a static projection, which like all static extrapolations, completely fails to take into account the future potential of humans to adapt and innovate. Should supplies of lithium falter, there are alternative battery chemistries already being developed. Alternatively, the extended range design with backup electricity generating capacity could become the dominant engineering solution for vehicles, meaning the average battery size could be much smaller. There should never be enduring shortages of any fundamental human need, energy, water, food, shelter, or transportation, because our capacity to invent new solutions always exceeds the rate at which we deplete resources necessary for existing solutions.