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lead-acid, lead-acid will likely have a niche role to play in coming years. The annual amount of waste expected from EV batteries in the U.S. was projected out to the year 2005 based on a set of reasonable assumptions in order to compare with the capacity for secondary lead recovery. The long-term trend in U.S. secondary lead recovery capacity is slowly upward, but the existing capacity in 1996 was taken as a conservative estimate. The following assumptions were used in arriving at this projection:

• A total U.S. EV population of 2000 in 1994 [19]

• A 3-year replacement schedule for lead-acid batteries in EVs

• Market share for lead-acid batteries decreasing from 100% in 1995 to 30% for 2000 and beyond

• Improved energy density for lead-acid batteries from 30 Wh/kg in 1995 to 50 Wh/kg in 2005

• Battery mass per EV of 500 kg in 1995 and decreasing with improved energy density

In retrospect, most of these assumptions were good, but there were a few that were not. It now appears that EV sales in 2003 will more likely be 10 to 15% of the 200,000 predicted by the Energy Information Agency in 1996. Since a large fraction of these vehicles could well be hybrids using advanced battery technology, the constant 30% market share for lead-acid batteries beyond 2000 is probably also too high. A less important factor is the predicted decrease in battery mass per vehicle as energy density improves. Although this trend may occur at some point, it is probable that the desire for more on-board energy storage will continue unabated for at least the near term. The introduction of advanced batteries with higher energy density has not led to consistently lower weight batteries, but more often than not the incorporation of more battery capacity.

Nevertheless, the assumptions were conservative in the sense that the predictions based on them likely represent an upper limit for the impact on the lead-acid battery recycling industry. The mass of lead in scrap EV batteries is projected to increase as shown in Figure 9, reaching about 16,000 metric tons in 2005. This can be compared to Figure 10, which shows the amount of lead from battery scrap and the total amount of lead recovered from scrap in the U.S. through the year 1995 from U.S. Bureau of Mines data. Total secondary lead is nearing 1M metric tons per year. The predicted EV battery lead mass in 2005 is only about 1.5% of the secondary lead recovery capacity in 1996 and will actually be less than that in 2005 once the future growth in secondary lead recovery is included. Clearly EV battery waste will remain a very small portion of secondary lead production well beyond 2005.

Nearly all of the secondary lead is recovered by thermal smelting, which does raise concerns regarding air and water pollution. Emission control devices are necessary to prevent the release of lead particulate to the environment, and in at least one case a backup battery has been installed to ensure that these emission controls continue to operate in the event of a power outage from the local electric utility [21]. However,

Year

Fig. 9. Projected Mass of Lead in EV Batteries to 2005.

Year

Fig. 9. Projected Mass of Lead in EV Batteries to 2005.

Year

Fig. 10. Lead from Battery Scrap, Total Lead Scrap, Secondary Lead Recovery Capacity, and Lead Scrap Export in the U.S.

Year

Fig. 10. Lead from Battery Scrap, Total Lead Scrap, Secondary Lead Recovery Capacity, and Lead Scrap Export in the U.S.

when such a large mass of lead is processed, it is virtually impossible to prevent the release of small amounts during the processing. Nonthermal methods such as electrowinning have been investigated for secondary lead recovery and in some cases have been shown to be technically feasible [22], but these methods have not been widely adopted, mainly due to high costs. More detailed information on recycling processes for lead-acid and other batteries can be found in other sections of this volume.

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