Dead Weight Loss
Electric vehicles need to lighten up. Literally.
(Today’s blog is co-authored by Blake Shaffer, who is an Assistant Professor at the University of Calgary.)
Let’s get something straight, again. If we want any chance in hell of getting to net zero, we need to electrify the vast majority of end uses and decarbonize the grid. Electric vehicles (EVs) have a big role to play here.
But EVs are still – vehicles. Warts and all. And as three bald guys (the two of us and Costa Samaras of Carnegie Mellon) point out in Nature this week: they are heavy. And heavy vehicles come with costs. So let’s recap and expand a bit on the points we make in the piece.
When Garth Brooks rides his future electrified Ford F-150 Lightning around downtown Nashville, with his battery in low places, he is bringing along 6500 pounds of steel, battery and perceived toughness. We are into comparisons. That is the equivalent of two Toyota Camrys. Or a regular internal combustion engine powered F-150 plus 1550 pounds of battery and support weight. That is the weight of an American Bison or a Holstein Cow. As Mike Anderson and Max pointed out many moons ago, heavier vehicles impose an externality on other traffic participants. Garth is safer, but everyone else is less safe if they get hit by a much heavier car than if Garth had bought the regular F-150. This is a classic externality story.
In our piece we compare that externality from additional weight, as measured by lives lost, to the climate benefits from driving the F-150 Lightning, considering both the current and future grid carbon intensity. The figure below shows what we found. The Y-Axis measures the social cost of the F-150 lightening’s additional weight and its climate benefits, if it were plugged into different (current and some future) grids across the world (as shown on the X-axis). The weight externality does not vary by how dirty your grid is, but the climate externality does.
If you are into nerdy calculations, we use the increased probability of death from getting hit by a heavier vehicle, combined with the probability of being involved in an accident and the differential in weight to calculate a weight external cost per mile, which assumes average miles driven for trucks in the US. We’ll gladly send you the spreadsheet if you’d like it. You may not like that we use an older paper, using largely internal combustion energy powered vehicle accidents from ten years ago or more to calculate the externality of weight. But this is what we have to work with currently.
Using an admittedly high (but Max thinks probably closer to truth than $52) social cost of carbon of $150 per tonne, the climate benefits (in blue) outweigh the weight externality (in red) in some countries (the blue dots indicate the emissions intensity and, thus, emissions benefits of an EV per kilometer for each country). In most places, however, it doesn’t—yet. The social benefits of EVs will of course improve as these grids get cleaner over time. So we make the following four points:
- We should tax vehicle weight for all cars (internal combustion engine and EV), preferably per distance driven! It’s not just how heavy your car is, but also how many miles you drive it. If we could come up with weight-based mileage-dependent registration fees, this would send the right signal. Some places do charge more to register heavy cars. France is at the forefront with some very steep penalties for heavy cars – yet they exempt EVs.
- We need to shrink batteries and lighten frames. As awesome superdad economist Chris Knittel pointed out for combustion engines, much of the technological progress has been funneled into power and range, rather than lower weight and fuel economy. But now that we have ranges of 300 miles and fast charging, we should contemplate making cars and batteries lighter instead of making them go further. The benefits of range and power accrue to Garth (the driver) and not Dolly (another driver or pedestrian).
- We need to make progress on reducing crashes, some of which can be achieved by technology. Warning systems like lane departure and collision avoidance will help. Also, somehow preventing people from using their phones while driving would help.
- Finally, we need to get people to drive less. We are not trying to ruin your life, but do we really need to drive 6500 pounds for three miles for one person to pick up a gallon of milk? The answer is a clear no. Removing the implicit subsidies cars enjoy (free parking, a road system and urban design centered around a car economy) has to be a long run goal. Anyone who has spent time in cities like Barcelona very quickly realizes how pleasant a less car intensive society can be. Less noise, less smell, less climate change, fewer accidents and let me count the ways!
So why blog about this when we’ve published that nice piece in fancy Nature? One reason is “The Skeptical Environmentalist”, Bjorn Lomborg, who is heating up Facebook with a graphic that tries to suggest that our piece says EVs are uniformly bad. That is simply a gross and reckless misrepresentation. The answer to the weight problem isn’t “EVs are uniformly bad”. Heck, it isn’t even “EVs are bad”. No, the takeaway from our piece is that in addition to accelerating the decarbonization of electricity systems, we need to make EVs lighter to reduce the weight externality and reap all the real and important climate benefits of going electric. For someone like Lomborg, who spends so much time reminding folks of the tremendous capacity for human ingenuity and innovation, it should come as no surprise that continuing progress in battery and materials technology is likely to allow us to lose that weight, which is great news.
But the more important point that will not go away is that an EV is still a car. We should remember that we have not managed to make great headway in addressing the non-emissions related external costs for any car. We need to continue working on doing so, including lowering vehicle weight, to avoid simply swapping one externality for another.
Keep up with Energy Institute blogs, research, and events on Twitter @energyathaas
Suggested citation: Auffhammer, Maximilian and Shaffer, Blake. “Dead Weight Loss” Energy Institute Blog, UC Berkeley, October 25, 2021, https://energyathaas.wordpress.com/2021/10/25/dead-weight-loss/
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Maximilian Auffhammer View All
Maximilian Auffhammer is the George Pardee Professor of International Sustainable Development at the University of California Berkeley. His fields of expertise are environmental and energy economics, with a specific focus on the impacts and regulation of climate change and air pollution.
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Very clever point. Which is sad.
Pedagogy: Even after several minutes studying it, I cannot tell which direction on the graph is “better.” Normally I would expect low costs are better (downward), but the inverted horizontal axis and the two blue messages makes me unsure. I tell my students to put an arrow pointing in the direction of better outcomes. You can also use text in the caption (“lower is better”) but arrows are clear and sparser.
Max, I’m not buying the assumption a Ford F-150 that weighs 6,500 lbs is significantly more dangerous than an ICE-powered F-150 that weighs 5,000 lbs. It’s definitely less dangerous than a Ford F-250 (7,500 lbs), and it’s the fuel that’s powering the driver we really need to worry about.
Maybe it is more dangerous. But if so, that would be the only argument for discouraging driving on a nuclear-powered grid. On such a grid, a heavy electric truck generates no more CO2 emissions than an electric Cooper Mini – so if someone wants to take his electric F-150 for a Sunday drive, there’s no increased climate impact. His fuel cost would be higher, of course, but that’s the owner’s choice to make.
The first job is cleaning up the grid, then electrification. By putting cart before horse, we risk undoing all the gains we’ve made if we’re still dependent on natural gas to power it. The discovery that up to 3% of extracted natural gas is leaked into the atmosphere suddenly puts gas in the same GHG-emissions league as coal, and contrary to popular superstition, solar and wind certainly aren’t replacing any gas (consumption in the U.S. is increasing faster than wind and solar combined).
The weight of EVs and the three other concerns mentioned are the least of our problems. We need to identify how to generate the required electricity and how to deliver it to the EVs. As we get ready to close down Diablo Canyon, and also electrify our buildings HVACs, finding adequate electrical energy and delivering it to the EVs is going to be the constraint..
“As we get ready to close down Diablo Canyon, and also electrify our buildings HVACs, finding adequate electrical energy and delivering it to the EVs is going to be the constraint…”
Good point. Or maybe we don’t close down Diablo Canyon, and avoid all those constraints. Maybe we avoid spending $3.7 billion on decommissioning a perfectly safe, state-of-the-art nuclear plant, and instead direct it to providing PG&E with a Zero-Emission Credit to keep it open. Maybe direct some of that money to upgrading transmission, to accommodate electric vehicles.
Maybe we ignore California’s gas lobby, and do what’s right for the environment instead.
Your graphic implies that you used a single estimate of fatality rates per vehicle-pound across all nations. That’s highly unlikely. The rate will vary for several factors include congestion and speed and the dispersal of the population of vehicles. And of course the US grid not a single universal grid (as Texans), so the emission rates should be separated at least by ISO and region.
There’s also uncertainty around the estimates of fatalities relative to weight. I haven’t looked at this data in 15 years, but it certainly was unclear then, including in a study by NAS. If all of the vehicles are heavier due to batteries it’s relative weight differentials that drive most of that difference, so that will change as the fleet changes.
Safety and efficiency! I plopped down my $1,000 deposit for a Rivian R1S. I’m having second thoughts now I see its less than 4 km/kWh consumption, and likely worse with the max battery pack, when it’s available. Actually, the F150 lightening isn’t great either, and while Tesla is doing better with its current models, we haven’t seen the Cybertruck yet. CAFE for electric vehicles?