But that’s simply not true. We know what lithium-ion batteries are capable of. And we know the kWh, size, and weight of the battery needed to move a truck of given weight a certain number of miles. That makes it possible for scientists to work backwards and figure out how many kWh the battery would need to be to go 300 to 500 miles, what it would weigh, and the likely price for the battery needed for a truck at the maximum road limit of 80,000 pounds.
S. Sripad and V. Viswanathan (2017) at Carnegie Mellon have done just that. They published a paper in the peer-reviewed American Chemical Society Letters at the following link: Performance metrics required of next-generation batteries to make a practical electric semi truck. Below is my review of their paper along with some additional cited observations of my own.
— Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
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Authors S. Sripad and V. Viswanathan felt compelled to write their paper because there are so many guesstimates of the likely cost and performance of an electric class 8 semi-truck in the media. But these hasty calculations don’t take into account critical factors like the specific energy density of the battery pack, vehicle weight, drag, rolling resistance, battery kwH to go a given distance, and weight of the batteries given current Li-ion battery technology.
The average class 8 truck, empty, weighs around 31,000 to 37,000 pounds. The tractor (the cab in front) weighs around 17,000 to 20,000 pounds. If you subtract 4,000 pounds of power-train weight (diesel engine, cooling system, transmission, and accessories), the cab of the truck, where the driver sits, is about 13,000 to 17,000 pounds.
The authors agree: they estimate “the average empty truck weight is 6,000 to 8,000 kg (13,228 to 17,637 pounds) without the weight of the engine”. They also imply that the empty truck weighs 13 to 17,000 pounds later on when they point out that the battery for a 600 mile range would weigh 18 tons (36,000 pounds), “twice as much as the empty vehicle”.
But oops! They forgot to add on the weight of the empty container and chassis where the payload is. That adds another 16,000 pounds (8,000 pound empty 40 foot container, 8,000 to 10,000 pound trailer, i.e. chassis). So my weight estimate of 29,000 pounds is closer to what a class 8 electric truck will weigh.
This is why my estimates of payload are always about 10,000 pounds less than the authors. Authors: 900 miles payload of 8,000 pounds, my payload minus 3,000 (it’s overweight by 3,000 pounds). Authors 600 miles payload of 24,000 pounds, my payload 15,000 pounds. Authors: 300 miles payload 44,000 pounds, my payload 33,000 pounds.
If the authors are also using the average payload, which is 75% of the maximum payload, which is what I use, that would further explain the difference. I think the maximum should be used because in the future, both electricity and diesel are likely to be more expensive, or even rationed. To maximize efficiency businesses will have to stop just-in-time delivery with half full trucks, and turn to full loads and inventories to stay in business. And a lot less packaging so products don’t “cube out”, fill up the truck before a maximum weight can be achieved.
Nor can electric trucks be made lighter with aluminum or carbon fiber. They’re too expensive. Unlike cars, where the average income of an electric car buyer is $148,158 (NRC 2015), and the amount of aluminum needed to light-weight the car is a small fraction of what a truck would require, the trucking industry is a cut throat business with razor thin profits. Light-weighting is out of the question.
The maximum weight of a truck allowed on the road is 80,000 pounds, so if the body weight of a diesel truck is the minimum 33,000 pounds, then the maximum amount of cargo that can be carried by a diesel truck is 47,000 pounds.
Since an electric truck weighs 4,000 pounds less, that ought to shoot up to 51,000 payloads. But it doesn’t because the battery packs weigh so much.
For example, the authors found that the weight of the battery pack needed for a truck to go 900 miles is 54,000 pounds. There goes the payload: 54,000 + 29,000 truck weight is 83,000 pounds, over the 80,000 pound road limit. And this truck that can not haul cargo will set you back $500,000 to $650,000 dollars for the battery alone.
A 600 mile range isn’t commercial either. For starters, the battery pack would cost $320,000 to $420,000 dollars, and on top of that you’ll need add another $100,000 for the body of the truck. To move a truck 600 miles requires a 36,000 pound battery + 29,000 pound truck weight and the truck can only carry 15,000 pounds, which is 32,000 pounds less than a diesel truck can carry.
Musk claims the range of the Tesla semi truck can be as much as 500 miles. Based on the figures in Table 1, that means the battery would cost $267,000 to $350,000 (also add on $100,000 for the truck body), and the battery will weigh 30,000 pounds + 29,000 pound truck weight and be able to carry only 21,000 pounds of cargo, which is 26,000 pounds less than a diesel truck.
Even if the range is on the low end of 300 miles, the battery will still be very heavy, with a battery weight of 18,000 pounds + 29,000 pounds truck weight and and only be able to carry 33,000 pounds of cargo, which is 14,000 pounds less than a diesel truck.
The bottom line according to the authors, is that a 600 to 900 mile range truck will use most or all of their battery power to move the battery itself, not the cargo. The cost of the battery is $160,000 to $210,000 plus $100,000 for the truck cab and trailer (minus powertrain), so overall $260,000 to $310,000, which is $140,00 to $190,000 more than a new $120,000 diesel truck and considerably more than used diesel class 8 truck, which can cost as little as $3,000.
If anyone in the trucking industry is reading this, I’d like to know if a 300 mile range with just 18,000 pounds of cargo is acceptable. I suspect the answer is no, because the Port of Los Angeles explored the concept of using an all-electric battery drayage (short-haul) truck to transfer freight between the port and warehouses, but rejected these trucks because the 350 kWh battery weighed 7,700 pounds and reduced cargo payload too much. Nor was the 12 hours or more to recharge the battery acceptable. Ultra-fast 30 min recharging was considered too risky since this might reduce battery lifespan, and bearing the cost of replacing these expensive batteries was out of the question (Calstart 2013).
Even if a way has been found to charge a truck in half an hour without reducing battery life, the amount of power needed to do that is huge, so new transmission, voltage lines, upgrading many substations with more powerful transformers, and new natural gas generating power plants will need to be constructed. Across the nation that’s many billion dollars. Who will pay for that?
It shouldn’t be surprising that a truck battery would weigh so much. Car batteries simply don’t scale up — they make trucks too heavy. The authors calculated that a 900 mile electric class 8 truck would require a battery pack 31 times the size and weight of a 100 kWh Tesla Model S car not only because of weight, but all the other factors mentioned above (aerodynamics, rolling resistance, etc).
If the Tesla Semi or any other truck maker’s prototype performs better than this, there are additional questions to ask. For example, new diesel trucks today get 7 miles per gallon. But the U.S. Super Truck program has built trucks that get an amazing 12 mpg. But those trucks are not being made commercially. I don’t know why, but it could be because this achievement was done by making the prototype truck with very light weight expensive materials like carbon fiber or aluminum, costly tires with less rolling resistance, and other expensive improvements that were too expensive to be commercial.
Performance can also be gamed – a diesel truck going downhill or on level ground, with less than the maximum cargo weight, going less than 45 miles per hour with an expert driver who seldom brakes, can probably get 12 mpg even though they’re not driving a Super Truck.
Who’s going to buy the Tesla Semi, Cummins EOS, Daimler E-FUSO, or BYD all-electric semi-trucks?
Most trucking companies are very small and can’t afford to buy expensive trucks: 97% of the 1.3 million trucking companies in the U.S. own 20 trucks or less, 91% have six or fewer. They simply aren’t going to buy an electric truck that costs roughly 2.5 times more than a diesel truck, carries half the weight, just 300 miles (diesel trucks can go 1,800 miles before refueling).
Nor will larger, wealthier trucking companies be willing to invest in electric trucks until the government pays for and builds the necessary charging stations. This is highly unlikely given there’s no infrastructure plan (Jenkins 2017), nor likely the money to execute one, given the current reverse Robin Hood “tax reform” plan. With less money to spend on infrastructure, charging stations might not even be on the list.
The big companies that have bought (hybrid) electric class 4 to 6 trucks so far only did so because local, state, and federal subsidies made up the difference between the cost of a diesel and (hybrid) electric truck. The same will likely be true of any company that makes class 8 long-haul trucks.
I constructed Table 1 to summarize the averages of figure 2 in this paper, which has the estimated ranges of required battery pack sizes, weights, cost, and payload capacities of a 300, 600, or 900 mile truck.
|Range (miles)||Battery kWh required||Battery Pack Cost at $160-$210 per kWh||Battery Weight kg / tons||Max Payload|
|300||1,000||$160 – 210,000||8,200 / 9||8.5|
|600||2,000||$320 – 420,000||16,000 / 18||5.5|
|900||3,100||$500 – 650,000||24,500 / 27||0|
Table 1. All electric truck data from figure 2 of Sripad (2017). A diesel truck Max payload is 23.5 tons. The max payload (cargo weight) is derived from the max truck road weight of 40 tons, minus battery weight, minus weight of the truck (17.5 tons).
As to whether the Tesla Semi will perform as well as Elon Musk says, it is not certain he will still be in business in 2019, because Musk and other electric car makers are competing for very few potential electric car buyers and with each other as well. There will never be enough electric car buyers because of the distribution of wealth. Sixty-nine percent of the United States population has less than $1,000 in savings (McCarthy 2016). At best the top 10% can afford an electric car, but many of them don’t want an electric car, don’t have a garage, prefer Lyft or mass transit, are saving to buy a house or survive the next financial crash. And if states or the Trump administration end subsidies that will further dent sales.
Nor will there ever be completely automated cars or trucks, because unlike airplanes, where pilots have 8 minutes of grace before the crash to go back to manual controls, there is only a second for a car or truck driver to notice that an accident is about to occur and override the system. The better the system is automated, the less likely the driver is to even be paying attention. So the idea that the poor bottom 90% can order an automated electric car to their doorstep isn’t going to happen. Nor can it happen with a driver – there is simply too little time to notice and react.
Just imagine if an automatic truck were hacked or malfunctioned, it would be like an attack missile with that much weight and momentum behind it.
Even if the Tesla semi’s are built in 2019, we won’t know until 2024 if charging in just half an hour, cold weather, and thousands of miles driven reduces driving range and battery life, if the battery can withstand the rough ride of roads, and be certain that lithium is still cheap and easily available.
The only thing going for the Tesla Semi is that electricity is cheap, for now. But at some point finite natural gas will begin to decline and become very expensive, even potentially unaffordable for the bottom 90%. As gas decline exponentially continues, all the solar and wind power in the world does no good because the electric grid requires natural gas to balance their intermittent power. There is no other kind of energy storage in sight. Utility-scale batteries are far from commercial. Although compressed air energy storage and pumped hydro storage dams are commercial, there are so few places to put these expensive alternatives that they can make little, if any meaningful contribution, ever.
Meanwhile, this hoopla may drive Musk’s stock up and distract from his lack of meeting the Model 3 goals, but investors have limited patience, and Musk has over $5 billion in debt to pay back. It may be that Elon Musk is banking on government subsidies, like the $9 million State of California award to the BYD company for 27 electric trucks — $333,000 per truck (ARB 2016), and the Ports of Los Angeles and San Pedro who will subsidize a zero emission truck that can go at least 200 miles.
There are many other news stories very skeptical of Tesla’s claims and why he’s making them. One of the best, which has additional issues than those I wrote about above is here (Randall, T; Lippert J. November 24, 2017. Tesla’s Newest Promises Break the Laws of Batteries Elon Musk touted ranges and charging times that don’t compute with the current physics and economics of batteries. Bloomberg).
ARB. 2016. State to award $9 million for zero-emission trucks at two rail yards, one freight transfer yard in Southern California. California Air Resources Board.
Calstart. 2013. I-710 project zero-emission truck commercialization study. Calstart for Los Angeles County Metropolitan Transportation Authority. 4.7
Jenkins, A. 2017. Will anybody actually use Tesla’s electric semi truck? Fortune.
McCarthy, N. September 23, 2016. Survey: 69% Of Americans Have Less Than $1,000 In Savings. Forbes.
NRC. 2015. Overcoming barriers to deployment of plug-in electric vehicles. Washington, DC: National Academies Press.
Sripad, S.; Viswanathan, V. 2017. Performance metrics required of next-generation batteries to make a practical electric semi truck. ACS Energy Letters 2: 1669-1673.
Vartabedian, M. 2017. Exclusive: Tesla’s long-haul electric truck aims for 200 to 300 miles on a charge. Reuters.
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