How much cleaner can an electric car get compared to one running on conventional fuels? The answer is important, especially when controversies like a study finding that a Prius could be dirtier than a Hummer add to the confusion. To answer the question you have to look at the life cycle of the product from manufacturing to usage to disposal.
Starting with disposal, there is no significant difference in emissions between electric and non-electric cars at this stage, which sees minimal emissions relative to making and driving the car. The main environmental problem in disposal comes from the battery. Part of the issue with older electric hybrids like the Prius from the study was their reliance on lead acid batteries rather than the lithium-ion batteries used in newer electric car models like the Tesla Model 3 or 2017 Chevrolet Bolt. In addition to not dealing with the toxicity of lead, the rarity of components in the newer batteries has prompted extensive recycling programs to avoid shortages of cobalt, nickel, and lithium.
Next, usage. An electric car is only ever going to pollute indirectly i.e. charging the battery using electricity from a power plant that burns coal. In the past and in certain areas that still rely heavily on coal, the emissions from those plants were hardly better than those put out by burning gasoline. Nowadays, however, the US grid is being inundated with electricity from natural gas (at about 50% the pollution than traditional coal plants) and renewables.
That switch to cleaner power sources means a lot for electric vehicle (EV) emissions, as the graph from Bloomberg New Energy Finance (BNEF) shows.
- for context, emissions free nuclear power supplies most of France’s electricity as opposed to heavy coal use in China.
Those cars may run twice as clean when they’re charged in a place that gets a lot of power from green energy, but the same car driving in a coal-burning region may yield a gain of just 20%, according to the Union of Concerned Scientists, based in Cambridge, Massachusetts.
Of course, fuel-efficiency standards are also pushing car makers to make engines that use less fuel.
What this means for their emissions relative to EVs is depends heavily on the state or country you’re in.
In France, the gap has to narrow in the coming decade because regular engines are getting cleaner and the energy mix can’t get much cleaner.
In Japan, emissions from driving electric vehicles may actually rise as nuclear power plants are replaced with natural gas and coal in the wake of the Fukushima Daiichi nuclear disaster.
For the US, the state you live in matters a lot for this discussion as shown in the BNEF map of the carbon intensity of power for each state.
Note the difference between coal state Wyoming and hydroelectric powerhouse Oregon.
For an idea how that map might change, look at what energy sources each state was installing in 2015.
A study done by the Union of Concerned Scientists found that making an EV results in 15% greater emissions than in manufacturing a similar gasoline vehicle. However, the same study was optimistic even this could be reduced and paled in comparison to the savings gained in the usage stage.
Assuming a grid composed of 80% clean electricity — France currently derives about 75% of its electricity from nuclear energy and about 14% from hydropower — the analysis would have a EV see at least a 25% reduction in emissions from manufacturing and an 84% reduction in emissions from driving. That combination would result in an overall reduction of more than 60% compared to today’s EVs, which are already about 40-50% cleaner than those running on gasoline or diesel.
So, basically, an electric car can get pretty darn clean, especially when the power grid that fuels it is running on renewable energy.