Sorry type O. The K rails test was not.50k in K rails that would put it over 82,000. Tare weights on a empty flat bed are 13_15000lbs so there was 40,000+ lbs of K rails either way counting up the K rails , plus the tare weight gave a mass of the Tesla Semi as somewhere between 25K and 27K lbs since it is not known if they went for the 82,000lb fed limit they only said it was 80,000+ lbs total gross mass.
Drivers say they love the Tesla Semi it’s shift less and has torque for dayssss at zero rpm typical of triple phase induction machines.
The way forward for long distance is to just copy what the most efficient means of land transport already does the diesel electric locomotive. Every day ICE powered generators move mile long trains at high levels of efficiency.
For truly long range OTR trucks the 40% or so that need 1000+ miles per day with three man 24/7 driving teams. A range extender generator is the way to go. You get all the torque of the electric drive train and the range of higher density fuels. This simplifies the drive train as there are no gears,no drive shafts just motors ,a few fixed gears and electrons. One drive train for both regional EV and range extended trucks for true cross country needs. Added benefit is running a ICE or turbine at a single speed let’s you design that load point for peak efficiency doubling at least the MPG for unit of fuel. You use the much smaller battery pack only to capture regeneration braking energy and to deal with peaks if torque demand.
A 150kw very efficient ICE to power a small light weights radial flux generator outputting 800V DC directly to the motors and battery bus is all that would be needed. 1.7kWh per mile average load is 127kw as 75mph the upper limit of any legal truck speed on an American road.
The choice of engine for the generator gets interesting a small gas turbine makes a lot of sense if you only need to run it at peak power down to 75% load that is the heart of a gas turbines sweet spot for low fuel consumption. Plus the high power to weight and high output rpm makes for truly tiny machines.
Anyone who has ever seen the 170KVA integrated generator on a 777 the largest jet engine in the world knows how tiny that unit is. It’s the size of a one horsepower 60hz motor you can pick it up with two hands easy. 170kva is 170kw at a PF of 1.
Why can it be so small and light well over 10kw output per lb of mass and that includes the CVT gears to keep it at 24,000rpm constantly. That last point is why a two pole 400hz generator runs at 24,000 rpm generator output is logarithmic related to the number of times the rotor poles cross EMF fields. 400hz output means a truly tiny generator puts out huge power. There is no need for 60hz output and the huge mass of those archaic machines.
For HVDC volts at 800v you drive a high speed genset at 400hz plus and 800ACV at the output terminals right into Silicon carbide rectifier full bridge diodes the output is then 800V DC with virtually no ripples as you have 800 plus minus peaks per second on the DC side simple capacitors smooth that right out.
Now you have what the electric drive train needs at very high eff and a compressor and turbine the size of a automotive turbo charger.with a hand held sized radial flux generator. Single shaft no gears no oil lubrication air bearings work above 12,000rpm the generator is the starting motor as well. Everything is air cooled except the generator it needs liquid oil cooling due to its power density a small trade off as the oil radiator and pump are fractions of the mass of air cooled generators of equal output. The whole system has five moving parts, two stage compressor, two stage turbine one rotor and a MRBF measured in the 40,000 hour range.
Turbines can burn anything flammable liquid or gas with very low NOx,and PM2.5 no expensive catalysts needed if you use lean burn low NOx burners and soot free fuels. Here again methane,propane,hydrogen,any of the alcohols all run in a turbine with virtually no emissions.
This eliminates the DPF,SCR and DEF systems saving thousands in emissions equipment that no one can legally run without nor should they diesels make horrific levels of particulate matter emissions visible to the makes eye even. Anyone who has been to the Asian megacites can attest to the eye watering levels of soot,NOx and smog from all those unfiltered diesels. Those days are over forever in first world countries.
Having a micro turbine range extender cuts the total mass of the truck to under what a stock diesel would be. The 150kw turbine and genset could be picked up by a single person at least a thousand lbs lighter than a diesel engine. The pack size needed for peaks and regen brake duty which saves brake pads wear significantly is in the 50kWh range that’s 67hp for an hour or 670hp over 6 minutes. The pack handles the peaks and takes the full 600+ hp regenerative braking energy.
Electric drive trains also have the ability to resistive brake just like a train set the motors to max generation and dump the current to resistive banks in the grill as heat just like a locomotive. Think descending down the continental divide and never needing friction brakes at all.
Two stage gas turbines are 35% efficient at 75% capacity and 38 ish at 100% capacity. This is where you are going to run the turbine on the open road at speed anyway. When you slow down in the city you have 50kWh of pack full charged that’s 85 city miles before the turbine fires up again to charge the pack since city traffic is so much slower than hwy the kw per hour needs of the truck are way less than 150kw every bit of surplus is pushed to the pack as recharge once it hits full spin down the turbine wash rinse repeat until the fuel tanks run empty. Hydrogen is a near perfect fuel for a turbine it has zero sulfur so not SOx is possible, with lean burn there is ppm levels of NOx and no particulate matter emissions. 1400 miles worth of Hydrogen at 300bar fits where the existing tanks are now and in 8 12” diameter cylinders behind the cab taking one linear foot of air space behind the cab there’s ten plus feet there now. Refill rates if 14 kg per min have been demonstrated. 1kg H2 is equal to one gal of diesel well .9 close enough.
Anything you can do with hydrogen you can do three times better with methane as methane has three times the energy per unit of mass. So 14kg min of methane is three times the energy flow as H2 gas and also those tanks of H2 if filled with methane take you three times farther. You could in theory go coast to coast on 300bar CNG not stopping for fuel.
The DOE goal for electrolysis H2 is $3 Kg this needs $400kg or less capex for intermittent electricity and $1200 or less for nuclear 24/7 electricity. Current capex is $500 for 30000hr PEM hydrogen electrolysis cells. So nuclear is already economic if we built more nukes. Ask Canada for the tech and have the Koreans build them. Korea builds CANDU reactors for $2800 capex in 60 months from first pour to busbar power. China has built two CANDU for less than that and also in 60 months.
https://www.nrel.gov/news/program/2022/fast-flow-future-heavy-duty-hydrogen-trucks.html
Thanks for your replies, most informative though over my head for the most part! I get the idea of ‘energy used per weight unit moved’ however, the simplest part of the subject. I hope that comes to fruition.