On Monday I published an article titled "Electric Vehicles, Front Loading The Filth" that discussed a peer-reviewed study from the Journal of Industrial Ecology titled, "Comparative Environmental Life Cycle Assessment of Conventional and Electric Vehicles" which found that:
"EVs powered by the present European electricity mix offer a 10% to 24% decrease in global warming potential (GWP) relative to conventional diesel or gasoline vehicles assuming lifetimes of 150,000 km. However, EVs exhibit the potential for significant increases in human toxicity, freshwater eco-toxicity, freshwater eutrophication, and metal depletion impacts, largely emanating from the vehicle supply chain."
That article focused primarily on the toxicity and metal depletion impacts of battery electric vehicles, or BEVs. Today I'm going to ignore the toxicity and metal depletion issues and focus solely on greenhouse gas emissions. The critical points I want to demonstrate for readers are that:
- BEVs double current GHG emissions from manufacturing while promising only modest reductions in future GHG emissions;
- Life cycle emission reductions are directly related to battery capacity and increasing battery capacity to combat range anxiety effectively eliminates the GHG benefit.
For the original study, the authors used the Nissan Leaf as their BEV standard and the Mercedes A Class as their ICE standard. Table S1-2, from the study's Supporting Information summarized the normalized climate change impacts for the various alternatives they considered in this table:
To keep my analysis as simple as possible, I constructed a new table that begins with an average of the study's values for Li-NCM and Li-FePO4 batteries for a basic BEV-24. Next, I adjusted the "Fuel/Electricity" values to reflect the fact that European grid emissions average 462 grams of CO2 per kWh while US grid emissions average 545 grams of CO2 per kWh. For the final step, I created additional columns for BEVs with 40 kWh, 60 kWh and 85 kWh battery packs like you find in the Model S from Tesla Motors (NASDAQ:TSLA) and adjusted the study's "Other Powertrain" and "Battery" emissions factors proportionally.
The first intriguing fact is that the simple act of increasing battery capacity from 24 kWh in the basic BEV to 40 kWh like you find in an entry level Tesla Model S effectively eliminates the life cycle emissions advantage. While a BEV-24 will reduce emissions by roughly 16% over the life of the vehicle, a BEV-40 will only reduce emissions by 3%. If you upgrade to a BEV-60 to combat range anxiety you suffer an emissions penalty of 13.6% and if you upgrade to a top of the line BEV-85 the emissions penalty rises to 34.3%.
While I find the life cycle CO2 emissions reduction benefits of BEVs underwhelming in the extreme, I think the front-loading of CO2 emissions in BEV manufacturing is appalling and inexcusable. In this graph that compares the four BEV options with a basic ICE, the manufacturing emissions are highlighted in red while the use and disposal impacts are highlighted in green.
Since manufacturing a BEV generates between two and five times the CO2 of manufacturing a comparable ICE vehicle, my last graph shows when cumulative CO2 emissions reductions from operating a BEV are large enough to offset the incremental emissions of making the BEV in the first place.
A BEV-24 using the average US grid mix takes a little over five years to offset the additional CO2 emissions associated with its production. For a BEV-40 the offset period is closer to nine years. There's no reasonable chance that a BEV-60 or BEV-85 will ever save enough CO2 in operations to offset the additional CO2 emissions associated with its production.
Whenever I mention the inconvenient truth that BEVs are simply internal combustion vehicles with extremely long tailpipes, some EVangelical chimes in with the idea of charging them from solar panels. That's a great theory for vampires who can sleep all day while their BEVs bask in the sun. For normal people who have to drive their cars during daylight hours, their solar panels will power somebody's air conditioner and toaster oven while the electricity used to charge their BEVs at night will come from coal and natural gas.
The entire solar charging argument is intellectual sophistry and rationalization of the highest order.