Published on June 13th, 2013 | by Andrew Meggison
Tesla Model S Emissions Vs. A Jeep Grand Cherokee
Does the Tesla Model S pollute more than Jeep Grand Cherokee? Analyst Nathan Weiss on the financial website Seeking Alpha claims that yes, the Model S is worse than a big SUV. In response, Green Car Reports’ David Nolan, a driver of the Tesla Model S, took a closer look at Weiss’s methodology.
Weiss’ main argument is that while the Tesla Model S is indeed a fully electric vehicle and thus uses no gas, when looking at emissions, one must focus on more than what is coming out of the tail pipe. Weiss focuses on the power plants needed to charge the Tesla as well as charging inefficiencies that lead to energy loss – including so called “vampiric power loss” which is the power used by the Model S even when the EV is off. Additionally, the resources needed to manufacture the batteries to power the Model S should be included in total emissions as well, according to Weiss.
Upon the first publishing of the article in Seeking Alpha, Weiss came to the conclusion that a Tesla Model S has a real world CO2 emission of 547 gm/mi. This is indeed high. The V-6 Grand Cherokee’s official EPA CO2 number is 479 g/mi, while the more powerful V-8 model’s official EPA CO2 number 592 g/mi. So at first glance it seems that Weiss is correct.
However, Weiss later amended the article placing the Tesla Model S CO2 emissions at 346 g/mi, well below the Grand Cherokee. The main reason for the reduction cited as a miscalculation concerning “vampiric loss”.
David Nolan came to a different conclusion. When Nolan did the research he came to a real world CO2 emission for the Tesla Model S of 292 g/mi. Nolan‘s calculation is much lower than Weiss’ first calculation, though not that much lower than Weiss’ amended calculation.
The authors differ mainly when it comes to the issue of “vampiric loss”. Nolan claims that Weiss’ understanding of the Model S battery thermal management system is incorrect. Weiss said in his article that energy was used to keep the Model S battery warm. This is incorrect according to Tesla. Thus, the “vampire loss” drops.
Additionally and perhaps more importantly, Nolan points out that the issue of vampiric power loss is only temporary. Tesla is working on a “sleep mode” for software improvements to reduce the dreaded vampire losses. The next major update that is due this summer is expected to cut vampire losses in half. By the end of the year, they will be virtually eliminated, according to Tesla spokesperson Shanna Hendricks reports Nolan.
In conclusion Nolan admits that the Model S is not perfect, and it does have comparable CO2 emissions as a Scion minicar. Perhaps more worrying to Nolan is Weiss’ calculation that power plant emissions give the Model S an effective level of NOx pollution about triple that of the EPA limit for gas cars and that effective Model S sulfur dioxide emissions equal that of about 400 gas cars. Nolan admits that he cannot refute those claims.
Yet there is hope on the horizon as America continues to embrace cleaner and cleaner alternative fuels. It is no longer a question of if America can green its entire power grid, but rather a matter of when. And one day, you may be able to drive your next-generation Tesla Model S guilt and emissions free.
Andrew Meggison was born in the state of Maine and educated in Massachusetts. Andrew earned a Bachelor’s Degree in Government and International Relations from Clark University and a Master’s Degree in Political Science from Northeastern University. Being an Eagle Scout, Andrew has a passion for all things environmental. In his free time Andrew enjoys writing, exploring the great outdoors, a good film, and a creative cocktail. You can follow Andrew on Twitter @AndrewMeggison