我国HEV废旧镍氢电池包中稀贵金属资源化利用环境效益分析

废旧动力电池包中含有丰富的镍、钴、稀土等稀贵金属,其资源化利用是实现混合动力汽车(Hybrid Electrical Vehicle,简称HEV)全生命周期绿色化管理的重要内容之一。随着HEV的不断发展,动力电池包在未来几年将逐渐进入批量报废阶段,其资源化利用的环境效益成为值得关注的问题。鉴于此,以丰田混合动力汽车镍氢电池包为研究对象,利用GREET模型和LIME值法测算出,相比于原生矿开采,单位废旧镍氢电池包中稀贵金属资源化利用所产生的环境效益为1083元;根据报废周期,对我国市场上现存的HEV镍氢电池包的未来报废情况进行预测。结果表明,这些电池包将从2018年开始迎来报废,在2021年达到报废高峰,至2024年基本完成报废;预计其稀贵金属资源化利用的环境效益,可累计达9421万元。提出了加强废旧动力电池回收体系和资源化利用体系建设的政策建议。

Environmental benefit analysis of resource utilization of precious metals in HEV spent Ni-MH battery packs in China

In recent years, the Chinese government has committed to promoting the use of energy-saving and alternative energy vehicles, aiming to reduce dependency on oil imports and address the air pollution problem. Hybrid electric vehicles (HEV) have been developed in China since 2012. As a key component of hybrid electric vehicles, Ni-MH batteries have entered its mature period and should be replaced 2-3 times during the life of a HEV. Spent Ni-MH power battery packs contain a wealth of rare metals (e.g., nickel, cobalt and rare earth). The green utilization of these spent Ni-MH batteries is important because of their environmental value. With the gradual popularization of the HEV, the volume of spent Ni-MH power battery packs will increase over the coming years. The environmental benefits of utilizing waste Ni-MH power batteries will therefore become an important topic. Many studies have explored the environmental impact of utilization of power batteries, but few of them have conducted quantitative research on the environmental benefits of the utilization of precious metals from these batteries. For this reason, they cannot recommend specific policies for use in the future development of the HEV industry in China. To fill this gap, this study calculated the energy-saving and emission reduction effects of resourceful utilization of three precious metals (nickel, cobalt, rare earth) from HEV Ni-MH battery packs, with the application of the GREET model proposed by the Argonne National Laboratory in the United States. In this paper, energy consumption, greenhouse gas, acid gas, and dust particles were used as indexes to calculate energy-saving emission reduction effects. The Ni-MH battery pack of the Toyota HEV was selected as a representative model, as it is currently dominating the market. The results reveal that the per unit resourceful utilization of the three precious metals in the HEV Ni-MH battery pack can save 5777 MJ of energy and prevent the emission of 435627 g of greenhouse gas, 18584 g of acidic gas, 138 g PM_2.5, and 304 g PM₁₀, when compared to primary ore mining. This saved energy and reduced emissions can be converted into environmental benefits of 1083 Yuan using the LIME value method. We took 2012 as a baseline year for predicting the number of spent HEV Ni-MH battery packs in China because China''s HEV industry has developed rapidly since 2012, and many Ni-MH batteries have been put on the market since then. Based on sales of HEV Ni-MH battery packs from 2012 to 2015 and their life cycle, the quantity and distribution of spent battery packs were predicted using the market supply A model. The resulting predictions show that these battery packs will start to be scrapped from 2018, reaching a peak in 2021, and be out of the market in 2024. If precious metals in these battery packs were recycled and transformed into resources, the environmental benefit could be considered to be worth a remarkable 94.21 million Yuan. Finally, we proposed recommendations for the Chinese government for the improvement of policies and regulation concerning China''s HEV spent battery recycling and utilization industry. First, we suggest that an extended producer responsibility (EPR) system for problematic recycling should be established and the reverse logistics network should be optimized. Implementation of economic incentives (e.g., the policy of trade-in, deposit-refund, and ecological compensation mechanism) to foster spent battery recycling should be introduced. Finally, it is important to create technical specifications and standards for dismantling and recycling.