Sustainability of Electric Vehicles that Use Lithium Ion Batteries- Juniper Publishers

Juniper Publishers- Journal of Robotics

Abstract

Climate change and depletion of fossil fuel resources have led to the promotion of the use of Electric Vehicles (EVs). Since most EVs use Lithium Ion Batteries (LIB), we analyze the amount of lithium required by LIB for powering electric vehicles in a scenario where all fossil fuel powered passenger cars are replaced by EVs. Based on the current proven reserves of lithium and existing production rate of passenger cars, our study indicates that the Earth could run out of lithium as early as within 51 years if all existing fossil fuel powered passenger cars are replaced by EVs.

Keywords: Sustainability; Lithium ion batteries; Electric vehicles; Lithium reserve

Abbreviations: EVs: Electric Vehicles; LIB: Lithium Ion Batteries

Introduction

Several public policies are being implemented around the world [1,2] to promote Electric Vehicles (EVs) in order to tackle the problems of climate change and fossil fuel depletion. In general, EVs produce fewer emissions that contribute to climate change and smog than fossil fuel based traditional vehicles [3]. Most EVs are powered by Lithium Ion Batteries (LIB) but other options include Nickel-Metal Hydride Batteries, Lead Acid Batteries and Ultra capacitors [4]. It is noteworthy that all of these powering options utilize naturally occurring substances on Earth that exist in a finite quantity. In this article, we analyze amount of lithium used in LIB to explore long term sustainability of EVs. We consider a scenario where all fossil fuel based passenger cars are replaced by EVs. Although the analysis presented here is for lithium, a similar methodology can be adopted for other power sources that require naturally occurring substances.

Analysis and Discussion

Lithium is a naturally occurring substance and Earth has a finite amount of lithium. According to the US Geological Survey [5], the current proven reserve of lithium is estimated at 14 million tons. In 2016, about 69.46 million passenger cars were sold according to The International Organization of Motor Vehicle Manufacturers [6]. The total number of electric vehicles sold in 2016 was about 0.75 million [7] which also includes plug-in hybrid vehicles. Therefore, if we imagine a future scenario where all passenger cars are electric and the number of cars sold per year remains constant at 2016 levels, at least 68.71 million EVs will have to be produced each year even at a very cautious estimate. A compact EV battery (Nissan Leaf) uses about 4kg (9lb) of lithium [8]. Consequently, around 0.275 million tons of lithium are required annually to produce EVs that replace all passenger cars under the considered scenario. At this annual rate of lithium consumption, the 14 million tons of proven global lithium reserves will be exhausted within 51 years. The recycling of lithium from used batteries is not taken into account here; however, it is important to note that EVs are not the only product that utilizes lithium. Only 39% of the total lithium production goes into battery manufacturing, while the rest goes into ceramics and glass, lubricating greases, and other applications [5]. Therefore, 61% of lithium application is not for making batteries, and even at conservative estimates it can be assumed that the recycled lithium from electric car batteries is used for making other non-battery products that use lithium. This does not thus significantly alter the estimate that lithium resources will run out within approximately 51 years.

In a more optimistic view, it should be noted that owing to continuing exploration the amount of lithium resources was revised to 47 million tons in 2016 [5] and is projected to be revised further to around 53 million tons. ('Resources' differ from 'reserves' in that a resource may not be technically, legally, or economically viable.) If the total lithium resource is therefore estimated at 53 million tons, the scenario discussed in this article may indicate lithium resources lasting, at a maximum level, for up to 193 years. That said, the assumptions made in this scenario are very conservative and may in fact greatly underestimate the lithium consumption rate. For example, total sales of new vehicles were roughly 93.85 million in 2016 [6]. However, we have only considered passenger cars and excluded other vehicles such as commercial, heavy duty or utility vehicles that need batteries with a higher power rating, and in turn need more than the 4 kg of lithium per battery assumed above. Another conservative assumption is that the sales of vehicles will remain constant at 2016 levels, which may not be very realistic as global vehicle sales tend to increase steadily over time. Furthermore, we have also neglected LIB that is used in other electronic products such as mobile phones. Additionally, LIB used by intermittent renewable energy systems such as solar photovoltaic's and wind energy have not been considered which may turn out to be a huge source of lithium consumption in the near future [9].

While it is a fact that EVs produce less greenhouse gas emissions than traditional fossil fuel vehicles [3,10], the notion that EVs are more environmentally friendly than conventional fossil fuel based vehicles might not necessarily be true in every case as environmental impacts of EVs can be dispersed and complex. For example, the life cycle assessment of EVs in the US estimates that throughout their lifecycle, EVs generate approximately three times the amount of human toxicity compared to conventional fossil fuel based vehicles [9]. Also, much of the cobalt and graphite entering the supply chain for lithium-ion batteries is sourced from poorly regulated and heavily polluting mines in the Democratic Republic of the Congo and China [9].

Conclusion

In this paper we have briefly described the long term sustainability of EVs that use lithium ion batteries. Our study indicates that the lithium reserves of Earth could be fully consumed within 51 years in a scenario where all fossil fuel based passenger cars are replaced by EVs. Although only lithium is investigated in this article, this research highlights the importance of rigorous analysis before exploiting any naturally occurring substance that exists in finite amounts on Earth and is non-renewable. Furthermore, this study lends support to the argument that our current energy and resource consumption pattern is not sustainable even taking into consideration apparently 'cleaner', non-fossil fuel reliant forms of energy.

For more open access journals please visit: Juniper publishers

For more articles please click on: Robotics & Automation Engineering Journal