Electrifying Big Rigs?
Electric Freight Transport’s Benefits Depend on Grid Decarbonization!
While much of the debate around cleaning up the transportation sector has focused on the types of cars you and I drive, one of the big sources of local and global air pollution is the big rig trucks shipping the stuff you and I consume around the country. There are roughly two million truck drivers on the road. And the average class 8 truck drives five times the mileage in a year compared to an average personal car. Further, these trucks are largely powered by diesel, which is a notoriously dirty transportation fuel, especially when it is burned in older trucks without modern emissions controls. So in summary, we have a large fleet of really dirty and heavy vehicles blowing diesel pollution into the air that people living near highways breathe. As I have written about before, California is trying to address this issue by decarbonizing heavy trucks. You might wonder how much decarbonizing this sector actually improves things.
In a paper hot off the presses, we (Fan Tong, Corinne Scown, Derek Wolfson, Alan Jenn and I) try to answer this question in a very specific way. We ask what would happen if we replaced the fleet of class 7 and 8 trucks with electric trucks and compare the consequential health and global warming damages to those from a fleet of modern diesel trucks. This turns out to be one of those ideas that seemed simple in the beginning and turned out to be brutally hard in the end. In order to spare you the details of what we did, let me draw you a picture.
We built a so called integrated assessment model, where we modeled:
- The flow of goods between origin and destination pairs
- The dispatch of trucks over different hours of the day
- Regulations of how long drivers can drive before they need to rest.
- Future electric battery & truck technology
- Future diesel truck technology and emission controls
- A future grid with varying degrees of integration of renewables and the resulting emissions
- Health and global warming damages from the resulting emissions
So we model a system that soup to nuts goes from being largely powered by diesel trucks to one that is fully powered by different types of electric trucks. Then we compare it to a system that is powered by modern diesel trucks with all the emissions control technologies required today, plus a little bump in fuel economy. This is different from the economics literature (e.g. this paper) that has tried to answer the question of whether a single electric vehicle is “better” than its internal combustion counterpart. That literature has used the marginal emissions from the current grid and not really modeled the consequences of additional load due to charging that vehicle.
What we are doing here is the large scale exercise of adding a bunch of electric trucks onto the grid, which is a massive increase in load across the country. We also acknowledge that a future grid is likely cleaner than the current grid and use Alan Jenn’s very cool model to do just that. So what did Max learn that he didn’t know before (which is a lot)?
- Electric trucks consume less energy than diesel trucks, assuming most of that electricity isn’t generated with fossil fuels. The end-use energy savings could be as high as 1 Quad (1015 BTU). This is largely due to the large inefficiency of the combustion engine in translating fuel into the energy to move the truck around.
- The health and climate impacts of electric trucks depend critically on the composition of the US electric grid. If we charge our future electric truck fleet on something resembling the current grid, most places in the United States are worse off in terms of health and global warming damages. This is largely due to the fact that the marginal power plants that come online for the significant additional load, are relatively dirty. As you can see in the figure above, damages are higher (red) for electric trucks for the status quo grid over most of the US (the West is, of course, best).
- However, with a high-renewable electric grid, the avoided damages from electric trucks exceed $5 billion annually, 80% lower than future diesel trucks. This is significant as this is what economists call “making the world a better place”. If the grid is AOC clean, plugging in a ton of trucks is better than shipping your Amazon boxes around in diesel trucks. You can see that in the same figure above, where the bottom right map is now mostly blue instead of red.
- There is an interesting opportunity here related to the belly of the duck. Trucks are dispatched (most commonly in the early morning) and drive long distances. Batteries aren’t yet cheap and light enough for electric trucks to last a full day on one charge, so drivers will have to stop during their trip and plug in. Yes, on a trip level there is much uncertainty about congestion and when trucks get where, but on average, one could manage a massive fleet of trucks to charge at times when there are excess renewables generated, that are cheap at the time. Combined with the right pricing structure, this could be a win win! Take the excess renewables off the grid operators’ hands and make sure little Betsy gets her new millennium falcon lego set on time! Or in fancy speak, the expected midday peak in charging loads according to our modeling could facilitate renewables integration, particularly in the Southeast and Mid-Atlantic regions where loads are highest.
Now, is our paper the final answer to this question? God no! It’s a tiny first step in a large number of papers that should be written. Here are a few questions that we do not answer, that are of key importance:
- What is the change of freight patterns due to electrification or other emerging technologies (e.g., truck automation, cashier-less stores, and further penetration of e-commerce)?
- What are the impacts of weather and aging on battery performance?
- How is growing urban traffic congestion going to affect health benefits from electrification?
- How much heterogeneity is there by commodity type, region, and by season?
- What are the (private) economics of electric trucks?
- How do you optimally roll out charging infrastructure?
There are of course many more. I am keenly interested in the role of hydrogen in long haul trucking and may write another blog post in a year or two, should we take a stab at this question. But to close, I think trucking is a vastly understudied area in energy economics and change is afoot. If we want change in the right direction, we better start answering some of these big questions!!!
Keep up with Energy Institute blogs, research, and events on Twitter @energyathaas.
Suggested citation: Auffhammer, Maximilian. “Electrifying Big Rigs?” Energy Institute Blog, UC Berkeley, June 28, 2021, https://energyathaas.wordpress.com/2021/06/28/electrifying-big-rigs/
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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.
Energy Institute Blog 
How about this perpetual motion machine: hydrogen/air fuel cells, hydrogen from battery driven water dissociation, recapture water, burn hydrogen in fuel cell, generate electricity, dissociate water. Oh, I guess we have to take energy out of the system somewhere but such a combination may have value.
Suggest you advance your timeline for expanding analysis to include blue & green hydrogen fuel cell trucks; compressed hydrogen storage gives trucks the range needed to complete with diesel. Your work could accelerate deployment of this zero emission fuel in the heavy-duty sector. Also curious why you didn’t include natural gas fueled trucks as your baseline for comparative analysis. Although still a fossil fuel used in ICEs, CNG offers significant emission benefits compared to diesel even when fugitive methane emissions are considered.
Your paper provides an interesting thought exercise, however your paper does not address key issues, specifically:
(1) Range limitations create a substantial barrier to Long haul trucking. Massive expansion of charging stations to address range issues would require an extraordinary investment and even the best estimates of recharge times would create delayed deliveries and increases in transportation costs. Even battery swapping options would be extraordinarily expensive both from a battery supply as well as service station investment.
(2) Regardless of the ‘battery’ option, the raw materials materials, mining, and production capability to produce sufficient batteries would impart horrendous environmental and political costs.
(3) Building out a carbon free, non nuclear, reliable electrical supply system sufficient to support a fully electric transportation network comes with its own massive cost, environmental and political issues.
“(2) Regardless of the ‘battery’ option, the raw materials materials, mining, and production capability to produce sufficient batteries would impart horrendous environmental and political costs.”
And continued fossil fuel production does NOT create “horrendous environmental and political costs”? This is the standard fallacy of this type of critique. It ignores the consequences of continuing our current tract. We actually have a hope of changing the standards in these nascent industries to minimize those future consequences while overcoming the current legacies are an enormous barrier almost certainly not going to happen.
“This is largely due to the fact that the marginal power plants that come online for the significant additional load, are relatively dirty. ”
This approach exposes the fallacy of “marginalism” when modeling dramatic infrastructure investment scenarios. When converting 4.5 million trucks with 1,700 GW of output capacity, we wouldn’t just ramp up the existing coal plants to power them. We would replace those plants with much greener generation sources. The system analysis must include the corresponding electric system changes–why would we otherwise bother to electrify trucks? This approach assumes immense stupidity on the part of policy makers. Economic analyses of these types of proposals need to move beyond the standard textbook model.
Nice post, and a useful article. I wonder, however, whether you took into account the Renewable Portfolio Standards in estimating the grid emissions. The short-term marginal unit may be gas, but if the energy supplier needs to provide 30%, 50% or 80% of sales from new renewables, the incremental emissions will be 70%, 50% or 20% of the NG emission rate.
How can I connect with Prof Maximilian Auffhammer? Most of what he notes in
his papers reflect the need to get transportation fuel under control, There are other
ways too that the Institute can focus on asap due to the need for a New Next Normal.
I’ve assumed that a battery swapping system is what will work for long-haul trucking.
I used to drive an electric forklift at the Turner Brass Company in Sycamore, Illinois. One of many crappy jobs that convinced me to finish college. We swapped the batteries once per shift. It took about 2 minutes to do. Roll up to a chain hoist. Pull the depleted battery. Drop in the charged battery. Keep moving. Those were heavier lead-acid batteries, but forklifts need a lot of weight on the tail so they can carry heavy loads on the forks without toppling.
For long-haul trucking, the truck would roll in, the driver would go to fill her coffee mug and empty her used coffee, and by the time she’s back in her rig, the robot would have put a fresh battery in.
It does mean that there are more batteries that trucks, but there are already more drivers than trucks, more trailers than cabs, and more wheels than engines, so the trucking industry understands how to manage that. The batteries could then be charged when the power is cheap. Probably a battery service vendor, possibly the big truck stop companies (Flying J, T/A, Love’s).
And for some locations remote from the beefy part of the grid, something like the propane-tank swapping operation at my local supermarket. Fresh ones come in on a truck, depleted ones go out. Less efficient, but allows for coverage in some areas that might need that.
A similar approach underway for barges on European waterways: https://insideevs.com/news/427049/ev-barge-concept-battery-swapping-zes/
In Norway, the Ampere ferry uses a different approach. The ferry docks are served by long radial lines, and the grid is not beefy enough to charge the ferry directly during the 10-minute turnaround times. So a shore battery charges slowly from the grid, and then zaps the onboard battery when the ferry comes in. That costs additional charging/discharging losses, but avoided a VERY expensive line extension. The lithium-ion batteries are recharged during the 10min loading and unloading time of each trip from the charging stations located at each shore and directly from the local hydroelectric-powered grid at night. A 260kWh battery is also located at each shore to supply power to the vessel while it recharges.
I agree with the swappable battery option. This seems to me a safer bet than a miracle battery. One could also imagine a hybrid situation with multiple swappable battery slots. If you were stopping for lunch/dinner you could choose to swap one or your batteries but charge the other on cheap solar/wind electricity. Fast fuel would obviously come at a premium compared to slow fuel and this would vary considerably. We’re starting to see smart water heaters that are able to decide when to charge based on multiple factors. The goal of the water heater charging logic is to minimize charging costs by maximizing the use of rooftop solar production and avoiding charging from the grid during expensive hours. The same logic would apply to fueling trucks and many other things. I would guess the percentage of charge coming from RE should be up around 90% +/- 5%.
How many TWh of annual charge do you think we could shove into the hours with cheap wind or solar? This saves a lot of electricity that would otherwise be thrown away. It would be interesting to see if this was more beneficial to wind or solar.
Great article. I’d love to see proposed charging pattern for heavy trucks juxtaposed to the charging pattern in the recent Berkeley Transportation study. I can’t recall seeing many studies that dynamically change charging patterns based on the expected wholesale prices.