Life cycle assessment on the reuse and recycling of the nickel-metal hydride battery: Fleet-based study on hybrid vehicle batteries from Japan

With the increasing popularity of hybrid vehicles, which were initially commercialized from Japan, the use of nickel-metal hydride (NiMH) batteries has also increased dramatically. This will inevitably lead to a large number of NiMH batteries in the future. This makes the reuse and recycling of these waste NiMH batteries an urgent concern. Nevertheless, the environmental burden generated from the reuse and recycling processes has not been clarified. Moreover, many NiMH batteries are exported from Japan to developing countries and will eventually be landfilled. Such problems severely weaken the efficiency of the waste battery recycling system in Japan. This research aims to analyze the environmental impact of a NiMH battery under each type of waste treatment strategy using the life cycle assessment (LCA) method. Then, a fleet-based LCA is performed to show how exactly the collection rate of waste batteries affects the efficiency of the recycling industry. The results show that, if we can reuse or recycle a waste NiMH battery instead of it being directly landfilled, the absolute environmental impact of the NiMH battery can be decreased. Especially in the reuse and recycle scenario, approximately 83 kg of CO₂ emissions, 1.37 kg of resource depletion, 0.044 m³ of landfill volume, and 1611 MJ energy consumption will be conserved for each NiMH battery. Moreover, the efficiency of the Japanese recycling industry would significantly improve if more waste NiMH batteries can be recycled or reused in Japan instead of being exported to developing countries.