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The available technology points toward the use of lead/acid batteries to supply the power for ZEVs. The negative consequences associated with lead/acid batteries are numerous. For example, lead/acid batteries contain a large amount of lead. When the life of the battery is lost, the disposal of the lead within the battery must be dealt with appropriately. An analysis by researchers at Carnegie-Mellon found that the mass production of electric cars using lead/acid battery packs would exponentially increase the public’s exposure to lead pollution (Peters, 1995). According to the study, electric cars would create more than 60 times the amount of lead pollution as compared to vehicles burning leaded gasoline (Peters, 1995). In addition to problems associated with lead pollution, lead/acid batteries also have the lowest energy density (compared to the batteries listed in Tables 1-4) because they use the largest mass of materials while offering the least amount of energy output. At 50 W· h/kg, a 25kW· h battery module would weigh 500kg (Gaines and Singh, 1996). The weight and inefficiency of the lead/acid batteries make them impractical to use and market as the main energy source of ZEVs. The technology to mass-produce lighter, longer running and affordable batteries does not seem to exist yet. Therefore, many argue that the hard push for electric vehicles will only contribute towards increased environmental damage. Although the practicality and environmental consequences of lead/acid battery use seem detrimental, the development of electric vehicles should not be forfeited. Other battery sources are available and are under investigation as a possible energy Table 1 Advanced Lead/Acid Battery Material Energy (Gaines and Singh, 1996) -------------------------------------------------------------------------------- Material Wt. % Production Recycling Energy per 25 kW· h (MJ) energy energy Virgin Recycled (MJ/kg) (MJ/kg) Batteries Batteries -------------------------------------------------------------------------------- Lead 69 27.1 5.3 9.4 1.9 Electrolyte 22 Sulfuric Acid 7.9 0.6 (est.) NA 0.02 0.02 Water 14.1 0.04 NA 0.0 0.0 Polypropylene 6.1 78.9 15.1 2.4 0.46 Fiberglass 2.1 25.9 21.9 0.26 0.23 Other 0.8 34.8 (est.) NA 0.14 0.14 Total 100 12.2 2.75 -------------------------------------------------------------------------------- Table 2 Sodium/Sulfur Battery Material Energy (Gaines and Singh, 1996) ------------------------------------------------------------------------- Material Wt.% Production energy Energy per (MJ/kg) 25 kW· h Virgin Batteries (kJ) ------------------------------------------------------------------------- Sulfur 12 0.9-9 0.03-0.27 Graphite Sodium 8 107 2.1 Ceramics 20 23 1.2 Steel <60 77 <11.5 Fiberglass 26 Other 35 (est.) Total 100 ~15 ------------------------------------------------------------------------- source for the electric car market. Sodium/sulfur batteries are one alternative to the lead/acid batteries. They have an energy density 300% that of the lead/acid batteries (Gaines and Singh, 1996). In addition, they have a life of 1000 charge and discharge cycles, which could eliminate the need to replace the battery during the life of the car (Gaines and Singh, 1996). Finally, the sodium/sulfur batteries would have a mass 250kg, half the mass of the lead/acid battery (Gaines and Singh, 1996). Therefore, car manufacturers would have to be less concerned about weight and towing impacts of the car. Environmentally, 63% of the elemental sulfur consumed in the U.S. is recovered as a by-product from processing crude oil natural gas (Gaines and Singh, 1996). Therefore, the environmental impacts of sulfur release into the atmosphere as a result of producing sodium/sulfur batteries are minimized. Other battery options under investigation are nickel/cadmium, nickel/metal hydride, and lithium batteries. Lithium is considered among the most promising designs for performance and cost, but safety and recharging questions still remain (Peters, 1995). Table 3 Nickel/Cadmium Battery Material Energy (Gaines and Singh, 1996) ------------------------------------------------------------------------------- Material Wt. % Production Energy
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Alternative fuels are perceived as being less likely to evaporate or otherwise find their way into the air before combustion and are less ozone-forming and less toxic if they do (Gushee, 1995). Another benefit that may be reaped from the use of alternative fuels is that gases burn cleaner than gasoline (see Table 6). As a result, less harmful emissions are created as a result of burning alternative fuels.
There are of course disadvantages to the use of alternative fuel driven cars. Vehicles that run on compressed natural gas will cost $2,500-5,000 more than a conventional car (Derr, 1994). Methanol does not offer convincing benefits over standard reformulated gasoline. Research shows that methanol does not offer any environmental benefits over reformulated gasoline and it is considerably more expensive
Table
Alternative fuels are perceived as being less likely to evaporate or otherwise find their way into the air before combustion and are less ozone-forming and less toxic if they do (Gushee, 1995). Another benefit that may be reaped from the use of alternative fuels is that gases burn cleaner than gasoline (see Table 6). As a result, less harmful emissions are created as a result of burning alternative fuels.
There are of course disadvantages to the use of alternative fuel driven cars. Vehicles that run on compressed natural gas will cost $2,500-5,000 more than a conventional car (Derr, 1994). Methanol does not offer convincing benefits over standard reformulated gasoline. Research shows that methanol does not offer any environmental benefits over reformulated gasoline and it is considerably more expensive
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