Big Rig EV blunder
In the world of commercial transportation, big rigs or semi-trucks are the unsung heroes of our modern economy. These colossal vehicles carry goods across vast distances, ensuring that products reach our stores and homes. However, as the world shifts towards sustainability and reducing carbon emissions, the spotlight has increasingly turned to electric big rigs. It is undeniable that electric motors have the power and torque to rival the big engines but to power those engines we need batteries. Can they achieve the same performance as an average big rig?
First some stats, the average power of Big Rig engine in America is 335kW and produces torque in the range of 6,779 Nm to 13,558 Nm with a max speed of 120kph. Max allowed weight of the vehicle on the road is 36,288kg weight,
To match the performance of an average big rig, we must ensure the electric truck has sufficient power and range.
All calculations are “off the cuff” so don’t yell about a decimal point here or a decimal there, we do these calculations just to see what kind of numbers we are talking about. It is understood that there are many, many variables and that the truck is not outputting its full power all the time, or going at highway speeds 24/7, that EVs have regenerative braking, trucks have variable load, and that aerodynamic effects play roles in the truck's energy consumption.
Electric vehicle batteries typically have an energy density of around 150 to 200 Wh/kg. Let's use 175 Wh/kg as an average value.
Now, we can calculate the battery pack weight (in kg) required to achieve the same performance:
BatteryWeight(kg)=E(kWh) / EnergyDensity(Wh/kg)
BatteryWeight(kg)=335kWh / 175Wh/kg ≈ 1,914kg
So, to match the performance of an average big rig, an electric semi-truck would need a battery pack weighing approximately 1,914 kg, or roughly 1.9 metric tons.
Let's assume you want an electric big rig with the same performance as described earlier but now let’s include in our calculations a range of 2000 kilometers (km) which is an average that, on a full tank of diesel fuel, semi-trucks typically travel with a tank of 300 gallons:
Power (P) : 335 kW (kilowatts)
Maximum Speed (V): 120 km/h (kilometers per hour)
To calculate the energy required for this range, we'll use the formula:
Energy(Joules)=Power(Watts)∗Time(seconds)
For a range of 2000 km at a speed of 120 km/h (16.6 hours), the energy required is:
Energy(Joules)=335,000W∗16.6hours∗3600seconds/hour=20.019.600.000Joules
Now, let's convert this energy to kilowatt-hours (kWh) for convenience:
Energy(kWh)=5561 kWh
As previously mentioned, electric vehicle batteries have an energy density of around 150 to 200 Wh/kg. We'll use 175 Wh/kg as an average value.
Now, we can calculate the battery pack weight (in kg) required to achieve the same performance and range:
BatteryWeight(kg)=5561kWh / 175Wh/kg ≈ 31,777kg
So, to match the performance of an average big rig and achieve a range of 2000 km, an electric semi-truck would need a battery pack weighing approximately 31,777 kg, or roughly the entire useful load of the truck leaving maybe a tone or 2 of cargo capacity and that is just ……
Battery weight is an additional and very problematic consideration. Speaking at a separate Technical Session at the TMC meeting, Bill Bliem, senior vice president of fleet services at trucking and logistics provider NFI, shared some actual vehicle and battery weights from his own fleet of pre-production battery-electric Class 8 tractors from Freightliner and Volvo Trucks.
“Fifty miles of range is going to require about 100 kW/h of energy, which right now weighs 1,375 pounds,” he said. “I'll let you digest that for a second, and you can do the math for longer ranges.”
Other weights and ranges he cited in his presentation included:
235 miles (480 kWh) = 6,600 lb
275 miles (565 kWh) = 7,768 lb
350 miles (750 kWh) = 10,300 lb
For the complete tractor, Bleim said, a typical diesel day-cab in his fleet weighs about 15,600 pounds, but an electric day-cab with a couple of hundred miles of range weighs about 22,000 pounds. As for the trucks he has ordered with a 350-mile range, he said they will tip the scales at 29,000 pounds without a driver and without a trailer.
Even Tesla can’t compete with diesel-powered trucks with their announced all-electric Semi. It has a max range of around 500km. Last month PepsiCo showed that its fleet of Tesla Semi has an average consumption of 1.1 kWh/km. On average, a modern diesel semi-truck can produce around 35 to 40 kilowatt-hours (kWh) of mechanical energy from 1 liter of diesel fuel. So 1 liter of diesel has almost 40 times the energy density of batteries. This can vary greatly depending on many factors, how old is the engine tech used, etc.
To determine the power consumption of a charging station that needs to charge 20 trucks per day, and 20 is not that many trucks, let's assume an average charging rate of 150 kW per truck. This value can vary depending on the specific charging infrastructure and the trucks themselves.
Time = 5561 kWh / 150kW = 37 HOURS
It would take a single truck 37 hours to fully fill its battery.
To fully charge 20 Trucks the grid would have to be able to deliver 111.22 MWh.
That is insane. That is almost 1/5th of the entire nuclear powerplant electric production like the R. E. Ginna Nuclear Power Plant in New York that would need to be allocated just for charging a truck stop for only 20 trucks.
Now, once again, these are oversimplified calculations. We can still use them to get some idea of what’s going on and what they illustrate is a picture that current infrastructure is woefully inadequate for an all-electric future with little progress on solving it in the US and in the West in general. China is building 21 nuclear power plants to fuel its economy while the West is building 5 new nuclear power plants in Total. Even Russia is building 3.
We all want an electric future, the engines are quieter, cleaner, and more powerful but our infrastructure mostly built in the last century is not up to the task of modern energy consumption let alone the new paradime shift in transportation needs.
So there’s the old environmental maxim that is more relevant today than ever before, think global act local.
The solution is to shorten the supply chain. No longer can we expect avocados in mid-December as they need to be transported from warmer regions.
Get to know your local farmers. Source locally and embrace seasonality, not all fruits and vegetables can be grown year-round.
Let's boil it down: transitioning from our beloved diesel-hungry big rigs to electric giants is no walk in the park. Heck, based on our number crunching, it seems like a gargantuan challenge right now. Massive battery packs, insane charging needs, and the looming shadow of our existing infrastructure—it's enough to make one skeptical.
If we just weren't so scared of Nuclear power. Maybe ITER will prove successful and melt all our misgivings away.
https://www.truckinginfo.com/10166691/what-fleets-need-to-know-about-electric-truck-batteries