Electric Semi Trucks
Published Friday April 10, 2015: Updated 9/9/2015
Electric Semi Trucks
What if EVERY vehicle were electric? Even the huge semi-trucks?
Technically speaking, the challenges involved in making almost every consumer vehicle on the roads 100% electric and pollution free, are solved. It’s just a matter of adding more charging infrastructure, converting our electric grid over to renewable energy, educating the public on the new paradigm of driving electric cars and having the political will to let it all transpire, instead of subsidizing the industries and monopolies resolved on stopping it.
It’s only a matter of time but it will happen.
But what about the rest of the vehicles? The big rigs and all the enormous trucks on the roads that transport all our goods around the country? Is it possible to electrify them too? And power them with pollution free, 100% renewable energy?
Well, let’s run the numbers and find out shall we?
A modern semi-truck carrying 80,000 lbs has a 430 to 620 hp diesel engine with a fuel economy ranging from 4 to 5 mpg.
Here is the typical energy efficiency of various engines in vehicles today.
Engine Efficiency Notes
Gasoline 20-30%
Diesel 30-49% Most semi trucks are 37.5% efficient
Electric 85-92% Virtually zero maintenance.
Gasoline engines running on compressed natural gas have the same energy efficiency or less. Natural gas is not as energy dense as gasoline.
As far as engines go, electric motors are very energy efficient. They are 3.7x more fuel efficient than a gasoline engine and 2.4x more fuel efficient than a diesel engine. Wow!
But John, doesn't it take coal to make Electricity?
Currently the electric grid is about 45% coal powered and as more coal plants close and get replaced with cleaner sources of energy, that number will continue to fall.
As someone who has personally been commuting ~10,000 miles per year in an effectively 100% solar powered car for almost 4 years now, I assure you those challenges are already solved and it’s just a matter of upgrading our 100 year old electric infrastructure to these non-polluting, renewable sources, like solar, water and wind. As the grid gets cleaner, instantly so do all the cars. So let’s stop intentionally holding ourselves back from what we can already accomplish right now.
It's time to electrify not just one model of hatchback or sedan of one or two makes, but all vehicles.
Where were we? Oh yes, electric semi-trucks. Right!
Because of the amazing torque of an electric motor, the requirement of a large, complex transmission is no longer necessary. Say goodbye to having to shift through 18 tedious gears and enjoy the instant torque and smooth, fast acceleration from 0-60 mph.
Going down steep graded, canyon roads, carrying a heavy load will no longer be a white knuckled driving experience either. With an enormously powerful 180 kW regenerative braking system, slowing down quickly, (even on a hill) is effortless. Nearly all the kinetic energy is recovered and fed back into the battery pack. No more noisy Jake brake and say goodbye to the dreaded run-away truck ramp. As is already the case with consumer electric cars, (thanks to regen), even the regular friction wheel brakes are hardly used in an all-electric semi-truck.
Since the truck is all-electric, when the driver needs to take a break or sleep, he or she won't have to keep the engine running in order to power all the cabin accessories. Just run them all in stealth, emission free, strait off of battery power.
Since electric motors are so much more energy efficient than their fossil fuel counterparts, a hypothetical electric semi-truck carrying a full, 80,000 pound load, with a 462kW (620 hp) electric motor (itself weighing only 250 lbs) would have an equivalent fuel economy of around 12-15 mpg, (where an equivalent diesel-gallon of electricity is 37.95 kWh).
So for a fully loaded electric semi-truck (carrying an 80,000 lb load) to have a 300 mile range, it would need a 948.75 kWh battery pack. WOW!
300 miles / 12 mpg = 25 gallons * 37.95 kWh = 948.75 kWh. For comparison, the Tesla Model S has an 85 kWh battery pack.
At 24.3 lbs per kWh, the electric semi-truck battery would weigh 23,054 lbs, (24.3 lbs per kWh x 948.75 kWh).
Keep in mind the front part (the cab) normally weighs 16,000 to 20,000 lbs but a large chunk of that is the enormous, heavy, diesel engine, transmission and fuel tanks. Much of this weight will go and is simply replaced for battery weight. In total, the all-electric semi-truck will only weigh a few thousand pounds more than its diesel counterpart.
At the current cost of Lithium batteries ($355/kWh in 2015), this colossal sized battery pack would cost $336,806. As battery costs fall to a projected $120/kWh over the next 5 years and energy densities continue to climb at an estimated 5% per year, this enormous, hypothetical battery may end up only costing ~$113,000. As battery chemistry and technology continues to evolve and improve, it will only get better, lighter and less expensive.
All together, for less than $175,000, you could have a long range electric semi truck that doesn’t need any diesel fuel and (besides washer fluid and tires), would require almost no maintenance for over 1 million miles.
Assuming there were some sort of super-charge network for semi-trucks which was powered from renewables, (like wind and solar) and free, just like the Tesla supercharger network, this truck could pay for itself through fuel savings alone in only 17 months. Engine maintenance cost savings would be icing on the cake.
Driving 600 miles/day, with a quick charge in-between, (5 days a week, 50 weeks a year), would clock in 150,000 driving miles per year. With 5000 charging cycles in a battery’s life, the battery pack would last about 7 years before it would need to be removed and recycled into a new battery back.
As battery costs continue to fall and battery capacities continue to improve, this hypothetical, all-electric semi-truck seems highly plausible. So what are we waiting for?
A Semi-Truck Super-Charger Station: What would it take?
Maybe it would make more sense to have a battery pack swap station where the semi truck would pull in, autonomously have its pack changed out and 90 seconds later you drive off with a full battery. This would make a lot of sense because the truck-stop could charge up many packs uniformly, all day long and then have the option of distributing them to the fleet quickly during peak demand periods.
But let’s assume we also want the option of quick charging the existing battery pack in 30 minutes. After all, the driver may want to grab a bite to eat and use the rest room before heading out for another 300 miles (4-5 hours) on the open road. If we have 30 minutes, let’s use it.
What would the charging infrastructure at an all-electric semi-truck, truck-stop require to quick-charge, not just one colossal 1000 kWh battery pack but 100 of them simultaneously? And in only 30 minutes?
To deliver 1000 kWh of energy in 0.5 hours requires 2 million watts of power. At 1000 volts, that’s 2000 Amps. That’s a lot of current but it’s not so ridiculous that it cannot be done right now, for a reasonable cost, with existing technology. If necessary we could even split that up into multiple sets of conductors per battery pack. It is doable, so let’s keep going with this hypothetical exercise.
A single truck stop with 100 quick charging stations would require 200 million watts of peak power. How are we going to provide all that power using only renewable energy?
Powering everything using only solar power and grid-storage
The solar panels collect the energy during the day and the grid-storage holds it until it is needed. The grid storage could be made using pumped hydro, molten salt, hydrogen (made from H20 and excess off-demand renewable energy), or even other batteries. It would require on the order of a 1.1 GW solar array, 3.3 square miles in size, and would cost around $2.5 Billion. That’s pretty enormous but there is also a lot of empty land near most truck-stops.
For the same cost that we spent defending our oil interests in the Iraq wars, the US government could have funded 1000 of these all-electric, semi-truck, truck-stops, (along with the large solar powered infrastructure), and placed them all across the US. And just like that, all trucking fuel costs would be free indefinitely. All that remains is the trivial cost of maintenance.
Imagine that? Being able to simultaneously charge up 100,000 electric semi-trucks, nation wide, every ½ hour, all day, every day, for life, for free?
Now remind me again why we still need fossil fuels?
Eventually we won't even call them "fossil fuels" anymore. Instead we'll refer to them as mineralogical resources and using them in a sustainable manner, for more useful things besides burning them.