LIFE CYCLE ASSESSMENT OF VEHICLE BATTERIES

Abstract

This study evaluated environmental impacts throughout the life cycle of the three types of vehicle batteries which were maintenance free, hybrid, and conventional batteries. Five environmental impacts were evaluated, i.e. global warming potential, acidification, ozone depletion, heavy metal emission and energy resource consumption. Functional unit was one unit of battery (12V) with the capacity of not less than 75 Ampere-hour (Ah) for pickup trucks with a life time of 4 years. The result showed that, without recycling scheme, the maintenance free, hybrid, and conventional batteries emitted GHGs gas 62.3, 83.4, and 119 kgCO2eq and sulfur dioxide 0.961, 1.21, and 1.66 kgSO2eq, respectively. The maintenance free battery released 4.35E-06 following by 5.67E-06, and 7.99E-06 kgCFC11eq by hybrid, and conventional batteries, respectively. The emission of heavy metal was from lead accounted for 4.54E-02 (maintenance free), 5.66E-02 (hybrid), and 7.44E-02 (conventional) kgPbeq. All batteries consumed energy throughout their lives, i.e. 1,072 MJ LHV for maintenance free, 1,462 MJ LHV for hybrid, and 2,116 MJ LHV for the conventional battery. The conventional battery affected the environment more significantly than the hybrid and maintenance free, respectively. The raw material acquisition stage and waste management stage were two main causes for the environmental impacts. The acquisition of lead resulted in a large quantity of gas being emitted, while sodium hydroxide used to neutralize sulfuric acid could pose some serious effect on the water course. This study proposed two options to reduce the environmental impacts: 1) Recycling materials from collected spent batteries, and 2) Replacement of sodium hydroxide (NaOH) with calcium hydroxide (Ca(OH)2). Each environmental mitigating option could be further classified into three scenarios, i.e. Option A (75% collection, Ca(OH)2 as pretreatment chemical), Option B (100% collection, NaOH), Option C (100% collection, Ca(OH)2 as pretreatment chemical). In general, Option C provided the highest potential of reducing most of environmental impacts. Option A gave the second best when focused mainly on global warming potential, ozone depletion, and energy resource consumption whereas Option B provided the second best performance when acidification and energy resource consumption. In part of economic analysis, maintenance free battery was better than hybrid and conventional batteries in terms of environmental consideration for purchase a new battery option. Turning in an old battery and purchasing a new one option was better for hybrid battery than the other two.