The environmental impact of disposable versus re-chargeable batteries for consumer use

Abstract

Goal, Scope and Background. The most common system for powering small items of electronics by both consumers and industry in Australia is simply to repeatedly buy and use disposable alkaline batteries. A growing practice however is to invest in a small battery charger and buy more expensive re-chargeables such as nickel metal hydride batteries. This latter course is promoted as being better for the environment. This study evaluates this assertion to guide future practice by both consumers and industry. The study compares re-chargeable AA batteries of both nickel cadmium (NiCd) and nickel metal hydride (NiMH) chemistry, each used either 400 times or 50 times with the number of AA alkaline batteries required to provide 1 kWh of energy to a device being powered. The scope of the analysis includes the materials and processes used in the production, distribution, use and disposal of the batteries and the battery charger and includes consideration of partial recycling and disposal to landfill. Methods. The study is done by developing an inventory of the life cycle of each of the alternatives which in the case of re-chargeable batteries includes the charger and the discharge & re-charging process. Measurements were conducted of re-charging efficiencies of representative batteries and of battery charger energy efficiencies. Energy use in wholesale and retail parts of the distribution system are also accounted for. SimaPro LCA software and associated Australian databases are then used to analyse the data using the Eco Indicator 99 (E) model of environmental impact. Results. The relative impacts of the three alternative systems on the categories human health, ecosystem quality and resource use showed little difference between the NiCd and NiMH batteries except for human health where the toxicity of cadmium gave a 20% advantage to NiMH batteries. When comparing re-chargeable batteries with alkaline batteries, the former caused less damage by factors varying from 10 to 131 for an optimistic scenario of 400 cycles of discharge and charge. Significant factors in the impact of the re-chargeable batteries were the production of batteries themselves, the electricity used for wholesaling and retailing, the transport to landfill and the copper and other components in the battery charger. For the disposable alkaline batteries the dominant impacts came from the electrical energy used for wholesaling and retailing the batteries, followed by the production of the batteries. Discussion. Most of the results are in line with expectations but somewhat surprisingly, the impact in most categories is dominated by the energy used in wholesaling and retailing, particularly for the alkaline batteries where the number involved is large. Also surprising is the fact that the cadmium present in the NiCd batteries was less significant than many other factors. The results however agree broadly with those of Lankey & McMichael (2000). Conclusion. Analysis results were overwhelmingly in favour of the re-chargeable battery option. This was true for every impact criteria studied and for less than optimistic scenarios of battery use such as significant shelf life or high discharge rates. Recommendation and Perspective. Given the present very large market for disposable batteries in Australia, there is a need for education of the consumer population and, to a lesser extent, industry, of the environmental and economic advantages of moving to re-chargeable batteries.