“If not for the compulsions of engineers, mankind would never have seen the wheel, settling instead for the trapezoid because some Neanderthal in marketing convinced everybody it had great braking ability.”
– Scott Adams

With declining fossil resources and the frightening impacts of climate change, the world has already started to adopt renewable energy and other climate-friendly services. One of several such initiatives is the inclination of the market towards electric vehicles. The idea behind the treatise is not to examine the sustainability of electric vehicles against fossil-powered vehicles but to analyze the environmental impact of electric vehicles solely. Accounting for all the direct and indirect emissions, no automobile can ever be carbon-neutral but leaping from a black smoky exhaust to a battery-powered vehicle is a relatively sustainable transportation approach.

As per EPA, for a typical passenger vehicle with a gasoline fuel economy of around 22.0 miles per gallon and which drives about 11,500 miles per year, the annual carbon footprint is 4.6 MTCO2e. This, however, is the direct emission from the tailpipe of the vehicle. The overall GHG emission attributed to any vehicle also constitutes indirect emissions resulting from the manufacturing of the vehicle, production & distribution of fuel used in the vehicle, and the maintenance of the vehicle. While most of these emissions will also exist in the case of an EV (Electric Vehicle) or a PHEV (Plug-in Hybrid Electric Vehicle) except for the tailpipe emissions. The tailpipe emission of electric vehicles is zero and for a hydrogen fuel cell-powered vehicle, the tailpipe emissions only consist of water vapor. In addition to the way a vehicle is manufactured and maintained, the source of electricity that is used to charge an electric vehicle is another contributor to GHG emissions attributed to EVs.

GHG emissions attributed to the life cycle of an EV vehicle with conventional power sources and non-recyclable battery (Pathways in "Red" contribute to GHG emissions). Individual icons from The Noun Projects. Flow diagram crated by Hemashree Kakar for SoilSphere.
GHG emissions attributed to the life cycle of an EV vehicle with conventional power sources and non-recyclable battery (Pathways in "Red" contribute to GHG emissions while those in "Green" are the relatively sustainable forms of conventional methods). Individual icons from The Noun Projects. Flow diagram crated by Hemashree Kakar for SoilSphere.

The Beyond Tailpipe Emissions Calculator by EPA provides an estimated value of GHG emissions in the US from an EV or PHEV depending on the model of the vehicle, the driving location, and the operational year. The importance of driving location arises from the fact that every location has a different electricity generation mix. To illustrate with an example here, a comparative study was performed between two locations; California (zip code: 90011) and Colorado (zip code: 80022) to analyze the effect of location. A comparison between six different models of EV and PHEV clearly illustrates the dramatic decrease in beyond tailpipe and upstream GHG emissions. In addition, due to the low proportion of coal-based electricity in this region (California, zip code: 90011), the net emission is lower than what would have been produced if the same vehicle was powered by the average US electricity mix.

Comparison of GHG emissions amongst six different EV models (California zip code: 90011). Source: fueleconomy.gov
Comparison of GHG emissions amongst six different PHEV models (California zip code: 90011). Source: fueleconomy.gov

An approximate estimate of the generation mix used corresponding to the location is taken from the Power Profiler provided by EPA. The location zip code used for the above comparison is 90011 and the generation mix is provided as below:

Fuel mix (%) of sources used to generate electricity in the selected location in California (zip code: 90011) and the national fuel mix (%). Source: epa.gov

The major difference in GHG emissions from any gasoline-based vehicle and an EV vehicle arises due to the absence of tailpipe emissions in the EV and the source of electricity that is being used to charge the EV. In the case when the source of electricity has a higher proportion of coal-based power in the generation mix, the data obtained shows a substantial increase in the GHG emissions from EVs. The following chart depicts the generation mix in Colorado, zip code: 80022.

Fuel mix (%) of sources used to generate electricity in the selected location in California (zip code: 80022) and the national fuel mix (%). Source: epa.gov

The proportion of coal-based power is higher in Colorado as compared to that in California. As a result, when the same EV is used in both these locations, the emission resulting in Colorado will be higher as compared to those in California. The following chart illustrates three different models of EV in two different locations to illustrate the effect of electricity generation mix on GHG emissions attributed to EVs.

Comparison of GHG emissions amongst three different EV models for two different locations (California zip code: 90011 and Colorado zip code: 80022). Source: fueleconomy.gov

Apart from the source of electricity and the efficiency of the vehicle itself, several other parameters need to be accounted for when measuring the sustainability index of EVs. One of the major concerns that arise in the advancements of EVs is the lifecycle of batteries and the material used in these batteries. Given the high energy density, power-to-weight ratio, efficiency, and performance of lithium-ion batteries relative to other alternatives, these are used in most of the EVs and PHEVs currently in the market. However, the projected scenario for the demand for lithium-ion batteries shows that more than 70% of the lithium reserves and more than 50% of cobalt will be consumed by these batteries by 2050. In addition, over 50% of the lithium reserves are found in the Lithium Triangle (around the borders of Argentina, Bolivia, and Chile). This further imposes a substantial logistics challenge to supplying the lithium to the manufacturing sites which in most cases will be thousands of miles far from the reserves. Apart from these, the biggest player that currently has majority control of the components used in lithium batteries is – China. China has 51% of the global total chemical lithium, 62% of chemical cobalt, and 100% of spherical graphite. In addition, these batteries impose a substantial financial challenge when it comes to recycling these to improve the end-of-life scenario. In addition to lithium-ion batteries, there is a rise in technology to develop better alternatives. Nickel-Metal Hydride batteries, Lead-Acid batteries, Ultracapacitors, Sodium-Ion batteries,  etc are some of the many such advancements in the progress. Many of the materials used in these batteries are not abundant enough to fulfill the global demand and will also impose logistics challenges. One of the significant steps towards battery development is Aluminium-Air batteries which, reportedly, have a high energy density, better performance, and are cheaper and less hazardous than Li-ion batteries. India, with abundant reserves of Aluminium (2300 million tonnes), has been heavily investing in breakthroughs and commercializing this technology.

To efficiently tackle the challenge of recycling the battery and vehicle material, it is essential to set the standards for design, manufacturing, material, and processes. In addition, it also demands a sense of responsibility from each one of us to back the science and technology that can bring a planet-friendly approach to transportation. The most vital aspect to consider here is not racing on a path similar to the dark history of oil and coal that impaired the planet to its roots.