By Clayton Handleman
With Electric Vehicles, the comment is often made that EVs are no better than regular cars when you take into account the emissions from power plants. The fleet average mileage for cars purchased today is under 25 mpg. Even using a more conservative number, 27 mpg, as in this Union of Concerned Scientists report EVs have a lower carbon footprint than the average ICE vehicle everywhere in the country. The UCS report goes on to point out that
In a more recent report from Climate Central the authors point out that the manufacture of EV batteries is very costly in terms of carbon. But even taking that into account, EVs beat the average car everywhere and beat a Prius in regions covering 30% of the US population. See HERE for explanation of the report’s flaws in describing the Tesla’s carbon footprint.
In all of the above cases, the case for EVs will continue to improve as more renewable energy is deployed. In fact from 2010 to 2012 the number of states where EVs are better than hybrids nearly tripled from 13 to 32 (not taking into account carbon from mfg). This was due to the build-out of renewables and natural gas. And the good news continued in 2013 with a banner year for solar installations and while wind deployment slowed dramatically from 2012 to 2013, 2014 looks to be another year of significant expansion.
In addition to improvements from cleaning up our electric generation sources, there is another trend that will tip the balance in favor of EVs. EV batteries do not die, they degrade. They are useful for other tasks even after they are no longer useful in the car. For example, repurposed EV batteries are being seriously considered for energy storage for the electric grid. This improves the stability of the grid. It also diminishes the impact of the intermittent nature of renewables and will allow for larger amounts of renewables to be added for electric generation. With more renewables, EVs become the better choice in yet more regions.
Unfortunately, many choose to compare EVs to the most efficient cars in the fleet. This really doesn’t make a lot of sense. EVs in the near term should be compared to the fleet average vehicle which they beat everywhere. In a recent paper the authors of ClimateFriendlyCarsReport emphasize the importance of including the EV battery in carbon footprint calculations. While looking at this issue is a good thing, the way the report evaluated the various considerations it offered a strange perspective in that it left one with a sense that EVs are not ready for prime time in terms of emissions reductions. That is not true and the report did a disservice through its lack of clarity on the matter.
UPDATE: This report, published in the Proceedings of the National Academy of Sciences supports the above conclusions with the exception of EVs operated in areas where coal is the primary power source. When taking into account all impacts they say that coal is so harmful that even with the benefits that EVs bring they still are more polluting that other sources for light transport when using electricity generated by coal. This blog post offers a nice summary of the report.
Tesla has a calculator that compares emissions for different locations for EV vs ICE
Links on repurposing EV batteries
Clayton Handleman, Electric Vehicle Emissions, Electric Vehicle, EV Emissions