From materials and batteries to manufacturing, calculating the real carbon cost of EVs is just getting started. Investors and politicians embracing a vision of an all-electric car future believe that path will significantly reduce global carbon dioxide emissions. That’s far from clear. A growing body of research points to the likelihood that widespread replacement of conventional cars with EVs would likely have a relatively small impact on global emissions. And it’s even possible that the outcome would increase emissions.
The issue is not primarily about the emissions resulting from producing electricity. Instead, it’s what we know and don’t know about what happens before an EV is delivered to a customer, namely, the “embodied” emissions arising from the labyrinthine supply chains to obtain and process all the materials needed to fabricate batteries.
All products entail embodied emissions that are “hidden” upstream in production processes, whether it’s a hamburger, a house, a smartphone or a battery. To see the implications at the macro level, credit France’s High Climate Council for a study issued last year. The analysis found that France’s claim of achieving a national decline in carbon dioxide emissions was illusory. Emissions had in fact increased and were some 70% higher than reported once the embodied emissions inherent in the country’s imports were counted.
Embodied emissions can be devilishly difficult to accurately quantify, and nowhere are there more complexities and uncertainties than with EVs. While an EV self-evidently emits nothing while driving, about 80% of its total lifetime emissions arise from the combination of the embodied energy in fabricating the battery and then in “fabricating” electricity to power the vehicle. The remaining comes from manufacturing the non-fuel parts of the car. That ratio is inverted for a conventional car where about 80% of lifecycle emissions come directly from fuel burned while driving, and the rest comes from the embodied energy to make the car and fabricate gasoline.
Virtually every feature of the fuel cycle for conventional cars is well understood and narrowly bounded, significantly monitored if not tightly regulated and largely assumption-free. That’s not the case for EVs.
For example, one review of 50 academic studies found estimates for embodied emissions to fabricate a single EV battery ranged from a low of about eight tons to as high as 20 tons of CO2. Another recent technical analysis put the range at about four to 14 tons. The high end of those ranges is nearly as much CO2 as is produced by the lifetime of fuel burned by an efficient conventional car. Again, that’s before the EV is delivered to a customer and driven its first mile.