BU-1002b: Environmental Benefit of the Electric Powertrain

Comparing environmental concerns on Powertrains

Believers of electric vehicles (EV) may overlook the environmental impact of manufacturing and driving a seemingly clean vehicle. What many policy makers and business leaders ignore is how polluting these cars are. The challenge goes beyond what comes out of the tailpipe and includes building the vehicles.

Figure 1 reveals higher CO2 contributions building an EV compared to a car with internal combustion engine (ICE). Long-range EVs with large batteries distort the numbers further.

This 2021 study by Bloomberg supports a 2019 report published by ADAC*, Germany, and Joanneum Research, Austria, saying that manufacturing an EV generates more carbon dioxide (CO2) than a vehicle with a conventional ICE engine. According to a research fellow at the Monash University in Melbourne, Australia, generating 1kWh of electricity by coal produces 1kg of CO2, similar to driving 6km (3.75 miles) in a luxury car. Manufacturing a 1kWh Li-ion produces 75kg of CO2, the same as burning 35 liters (7.7 gallons) of gasoline.

* ADAC is an acronym for Allgemeiner Deutscher Automobil-Club; General German Automobile Club. ADAC is Europe's largest motoring association.

Table 2 compares the CO2 emitted manufacturing and driving vehicles with a diesel engine versus an electric powertrain.

Based on higher CO2 emissions building an EV versus a vehicle with ICE, the EV needs to drive 225,000km to break even with a diesel-powered vehicle. (Volkswagen marks this odometer reading as the end-of-life of a car.) Labeling EV zero-emission is incorrect because, in many regions, electricity is generated by fossil fuel. Producing 1kWh of electricity by coal produces 0.94kg (2 lbs) of CO2.

Unless electricity can be produced from renewable resources, the EV does not provide the expected solution to CO2 reduction. A compromise is a mild hybrid with a small ICE and a 48V battery that reduces fuel consumption by up to 40%. A plug-in hybrid would provide most daily commuting by battery power. The focus should be on vehicle size and weight. A full-size EV battery weighs 500kg (1,100 lb) and represents 40% of the vehicle cost.

The planned CO2 reductions by 2050 may not be feasible or affordable with today’s technologies. Changing road transport from fossil fuel to electric is expected to double electric energy demand; however, EVs can be charged at night during low usage. Most houses are also heated with natural gas that generates CO2. Changing to electrical heat will further stress the electrical grid. Because of its high calorific value, air travel will continue to rely on fossil fuel.

A separate study in 2007, also done in Germany, claims that electric vehicles emit more CO2 than their diesel-powered counterparts. This reignites the debate of driving a Toyota Prius versus a Hummer. The CNW Market Research study includes energy costs from “dust-to-dust.” If the report is correct, the total environmental cost to society for a Prius is $2 per km ($3.30 per mile), while the Hummer comes in at $1.2 ($1.95). CNW includes energy costs to produce the vehicles from manufacturing to recycling and disposal of materials.

Many argue that environmental damage and energy consumption are synonymous. Electricity generation matters and should come from renewable sources. Being relatively new to the industry, hybrids and electric vehicles also incur high R&D costs. Then we must look at mining and processing of lithium, cobalt, and manganese used for the Li-ion battery. None of these are “clean energy” and the re-usage of recycled materials is often more energy-intense and costly than mining anew(See BU-311: Battery Raw Materials)

A report estimates that a finished EV battery represents 40% of the value of an electric vehicle. The Li-ion cells are energy-intensive to manufacture and use rare and expensive raw materials. Increasingly, these materials must be minded in an environmentally friendly way. Some materials, such as cobalt, may become short supply, affecting pricing.

Advances are being made to recycle Li-ion batteries(See BU-705: How to Recycle Batteries) to enable re-usage. Not all materials derived from recycled Li-ion by reach battery-grade level quality and may be used for other purposes. Lithium is also used as a lubricant.

Concerned consumers should buy a high-fuel-economy vehicle or bicycle to work. Physical activity also contributes to our personal well-being.

Environmental consideration in raw materials

When people hear the word graphite, they think pencil. Highly purified graphite will increasingly serve as materials to manufacture batteries. Natural graphite is at the heart of the energy revolution. It is an important component of lithium-ion batteries but current graphite purification involves processes that are hard on the environment(See also BU-309: How does Graphite Work in Li-ion?)

Used as anode material in Li-ion, natural graphite concentrate must be purified to contain less than 500 ppm of impurities. Current purification processes are mainly done in China and require a large quantity of chemicals that have a negative environmental impact. In the near future, purification can be done with new green technology, such as hydroelectricity.

Producing battery-grade lithium is also energy and resource intense. Lithium is commonly mined in tropical areas where efforts are made to use renewable resources for extraction and processing.

Life Cycle Emission

Life cycle emissions refer to production, use and disposal of a product expressed in tons of carbon dioxide equivalent (tCO2e) Table 5 compares CO2 generation of the internal combustion engine ICE), hybrid and electric vehicle (EV).

Note: Total amount of greenhouse gases emitted of medium sized vehicle over 16 years and 240,000km.
Source: Polestar and Rivian Pathway Report (2023)

The EV lowers tailpipe emissions, but switching from ICE to EV only reduces the overall emission from 100% to 71% in a full life-cycle of 240,000km (150,000 miles). Raw materials extraction and refining of lithium, cobalt, nickel and graphite are energy-intensive and polluting. We also keep in mind that roughly 60% of electricity is generated by fossil fuel. Solar and wind power alone are not sufficient to secure future electrical demand.

The switch to EVs could double the demand for electrical power; however, some charging can be done at night when load is light. CO2 reduction of an EV could also be achieved by mandating smaller and lighter vehicles.

Long-term investment should go beyond the private car and also improve public transportation. Efficient train service will provide a higher return in future generations than everyone driving a car that weighs 10 times more than the occupant. The ratio reverses with micromobility (See also BU-1006: Cost of Mobile and Renewable Power.)