It’s the widely accepted belief that battery electric vehicles (BEV) are inherently better at reducing greenhouse gas emissions than mild hybrid, hybrid, or even plug-in hybrid vehicles. That’s because, unlike the others, BEVs have no tailpipe emissions whatsoever. However, a new study suggests that mild hybrids, not BEVs, are most effective at reducing emissions.
- New study from Emissions Analytics suggests that mild hybrids, not pure-electric vehicles are more efficient at reducing greenhouse gas emissions.
- The study looked at the amount of CO2 produced per gram per kilometer driven per kilowatt hour of battery onboard.
- It argues that large-capacity BEVs are underutilizing scarce battery supplies that could be more efficiently implemented in hybrids.
Emissions Analytics, or EA, a firm that describes itself as “the world’s leading independent specialist for the scientific measurement of real-world emissions” released a study earlier this month that concluded that of all hybrid and electrified propulsion systems, 48-volt so-called “mild” hybrid vehicles were most efficient at reducing greenhouse gas emissions compared to traditional non-electrified internal combustion engines (ICE). EA states that BEVs are the least efficient way to reduce emissions.
On its surface, the conclusion seems pretty wonky and potentially biased. I mean, how can it be that BEVs are worse at emissions than a mild hybrid that generates most of its propulsion power from burning fossil fuels? EA argues that given the expense of mining and refining rare earth metals that are essential to BEV battery packs, the technology is better utilized on smaller scales. What’s more, large-capacity batteries are in high demand but suffer from supply challenges. For example, Audi had to recently reduce the production numbers of its e-tron quattro BEV crossover due to battery and electric motor supply shortages.
Suddenly, given that realization, Emissions Analytics’ conclusions gains some credence.
Think about it this way. Companies around the world are spending billions to develop BEVs that can do 300 miles or more per charge. And for what end? So people don’t have to recharge as often and at the same time don’t have to suffer from range anxiety. But those drivers are rarely ever going to utilize the full potential of the thousands of dollars of expensive lithium-ion batteries onboard. Rather, they’ll use 20% of their capacity and then recharge. So, they’re lugging around a bunch of rare earth metals so they can feel better about their vehicle’s potential range.
Rather than throw all those resources into one vehicle to ease someone’s mind, automakers could built dozens of plugin hybrids (PHEV) or maybe hundreds of mild hybrids with that same number of batteries. And those would do more to reduce emissions than that single BEV could. In this way, the argument makes a lot of sense. And, frankly, it’s the position that Toyota has had for many years, while many of its chief competitors jumped head first into EVs. Meanwhile, it remained focused on hybrids.
Buick Regal with eAssist mild hybrid technology. (Photo: Buick)
For those interested in the numbers and how they break down in grams of CO2 per kilometer a battery kilowatt hour reduces per propulsion type. Large-battery BEVs, EA claims, offer a reduction of 3.5 grams of CO2 per kilometer per kilowatt hour of battery capacity onboard. Hybrids manage 50.5g/km/kWh. Mild hybrids save 73.9g/km/kWh.
However, there is a catch. EA admits that its study “ignores the upstream CO2 in fuel extraction, refining and transportation, as well as in the production and distribution of electricity.” However, it argues that “some studies suggest the upstream CO2 of the electricity is greater than for gasoline, but the relative efficiency calculations here implicitly assume they are equal.”
From where I sit, Emissions Analytics conclusion is almost a moot point. The supply hurdles facing battery production and the relative low interest of consumers in BEVs to me mean that this is a problem we need not worry too terribly much about. The move to pure-electric vehicles will be a slow one in my mind. And many brands, like Volvo, are going to be making all their vehicles into mild hybrids.
Whether EA is right or wrong, the new-car market will have far more mild hybrids than BEVs for quite some time. They might be sweating a non-issue. I mean if the world’s vehicle fleet went 100% BEV tomorrow, we might be in trouble. But it’s not. So, I think we’re fine.