Published on September 6th, 2020 |
by Zachary Shahan
September 6th, 2020 by Zachary Shahan
A few days ago, I wrote about a new report by Ricardo for the European Commission showing (yet again) that electric vehicles “have significantly lower impacts on the climate.” It looks like the most comprehensive analysis of the environmental impact of electric vehicles versus fossil fuel vehicles. I noted in the article that there’s a common problem of much more limited studies coming to different conclusions that put electric cars in worse light, as well as simplistic and misleading headlines like “Electric cars aren’t as green as you think they are” or “Electric cars have a dirty little secret.” Well, a CleanTechnica reader, Albert Zonneveld, recently shared that there’s a new report out there focused on identifying and explaining the problems with those studies.
Researchers at Eindhoven University of Technology (TU/e) published “Comparing the lifetime green house gas emissions of electric cars with the emissions of cars using gasoline or diesel.” The summary highlights “the six biggest mistakes in studies that find electric vehicles have similar green house gas emissions as fossil fueled counterparts.” I’ll post a portion of the summary below to share those. However, I’ll first explain why my title says 5 whereas the study identifies 6. It seems to me that the first 5 points are specific and well argued. The 6th one is important and notable, but it’s more generic and sort of summarizing the other points combined. It is also mainly presented as being about future electric vehicles, not electric vehicles you can buy today, so it seemed outside the focus of the critique.
With that intro out of the way, here are the 5 or 6 things that lead to poorly conducted studies claiming that electric cars are not much greener than fossil fuel cars, in the authors’ own words:
1. Exaggerate GHG emissions of battery production
Scaling up and smarter engineering (e.g. preserving heat in the manufacturing process) have dramatically lowered the energy that factories require to produce battery cells. At the same time the electricity used is steadily decarbonizing. All this is reducing the EV’s ‘climate backpack’ but many EV-critical studies ignore this. Examples are Buchal, Karl and Sinn, ADAC, ÖAMTC and Joanneum Research that assume battery production will emit 175 kg CO2 per kWh of battery. They base this on one highly controversial study from 2017. But this study was updated in 2019 and concluded it was now 85 kg CO2 per kWh of battery which halves the ‘climate backpack’ of the electric vehicle. Mazda published a paper in 2019 using even older numbers. Based on a list of recent publications we assume a range of 40 to 100 kg/kWh with a mean of 75 kg/kWh.
2. Underestimate battery lifetime
In many studies the battery (e.g. Buchal, Karl and Sinn, ADAC, ÖAMTC and Joanneum Research) the battery is assumed to last only 150 000 km. Buchal, Karl and Sinn even contrast this to a diesel car lasting 300 000 km. However, we have not seen examples where this was based on actual research. Empirical data shows modern batteries will most probably last for more than 500 000 km. New studies claim two million km is possible with current technology. Furthermore, car lifetimes are increasing in Europe and an average modern car can be assumed to last 250 000 km. That is the battery lifetime assumed in this report.
3. Assume electricity will not get cleaner over the lifetime of the car
All studies that find high EV emissions assume the electric vehicle will drive on the electricity mix it used in its first year. This is understandable since it makes calculations easier and avoids having to defend assumptions on developments in the electricity mix. However, it is also unrealistic. Just as the electricity mix has changed dramatically over the past 20 years, it will do so again over the next 20 years. We extrapolate past developments and support our estimates using authoritative sources in order to create a future time series containing developments in the electricity mix. This basically means EVs drive cleaner as time goes on. However, this positive effect is partly negated by the fact that cars drive less as they get older. Furthermore, we must add upstream emissions of electricity because of e.g. digging up coal, electricity grid losses which we estimate to be higher than most literature at around 30%. All in all electric vehicles sold in Europe in 2020 should count on 250 g CO2eq/kWh electricity over their lifetime.
4. Use laboratory tests paid for by manufacturers themselves
Measuring CO2 emissions of cars is deeply problematic in Europe because the official numbers have become political instead of empirical. The test protocol is defined in political negotiations with manufacturers who then choose and sponsor the institutions that conduct the tests for them. This resulted in the successful application of cheating software and even fully tests using the New European Driving Cycle (NECD) result in emissions 40% lower than reality. Most studies that are critical of EVs still use the NECD. The new WLTP is supposed to be a fresh start but doesn’t address any of the aforementioned underlying problems so improvements are limited and — we fear — temporary. The WLTP is still useful for determining compliance but should not be be confused with empirical measurements of actual CO2 emissions. In this report we use road measurements (from spritmonitor.de) and independent test measurements with a good track record (from the EPA in the US).
5. Exclude or downplay fuel production emissions
New research into flaring and other sources of GHG emissions has shown that the emissions related to the production of gasoline and diesel are larger than previously thought. In order to account for the production of fuel, cars driving on gasoline should add 30% to their tailpipe emissions. Cars driving on diesel should add 24%. Emissions per litre are thus 3310 g for diesel and 3140 g for gasoline.
6. Ignore the larger system
The improvement that can be achieved with combustion engine technology is limited. First because it is a mature technology that only sees small incremental improvements. Second because producing the fuel combustion engines need in a sustainable manner is relatively inefficient and expensive. If we abide by the Paris agreement, the entire supply chain will become low carbon. Predominantly through the use of renewable electricity which will also be used for industrial heating processes using power-to-gas. This means that the ‘climate backpack’ of both conventional and electric cars becomes very small. What remains is the CO2 emitted while driving. Here the electric vehicle can directly run on renewable electricity and also has the advantage of its on average four times more efficient engine. The end result is that an energy system with enough renewable electricity will lead to electric vehicles that emit at least ten times less CO2 than cars driving on gasoline, diesel or natural gas.
That’s a good list of things to look out for in studies about electric vehicle emissions versus fossil fuel vehicle emissions. If you see some nonsensical headlines on this topic in the future (you are sure to), perhaps you can use the notes above to respond and either get that content fixed or at least help educate some of those who read it if the site has a comment section.
Anything to add to this good list and analysis? The one thing that I would pull out and make a separate point is the likelihood of battery recycling or reuse. Typically, studies on this topic assume batteries will not be recycled or reused after their time in the car. They assume 100% of the emissions of the battery’s production should be spread across the lifetime of the car, rather than acknowledging that if most of the battery is recycled or reused, only a portion of its production emissions should be put on the electric car’s ledger. Overall, though, the list and summary above is superb and the best thing I’ve seen on the topic.
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