6 ms·

Batteries on semis dont make much sense to me. Hybrid systems on heavy inner city vehicles make a lot of sense. As do hybrids in mountainous areas. But long d

Batteries on semis dont make much sense to me. Hybrid systems on heavy inner city vehicles make a lot of sense. As do hybrids in mountainous areas. But long distance hauling? BS. Semi engines are large with very low power to displacement ratio -> they are very fuel efficient. Truck builders' customers are very sensitive to fuel consumption. I find it very hard to believe that marginal grid power (ie thermal plant), through all the transformer and transmission losses can beat a semi's diesel. EDIT: even if the semi's electricity came from magic, the opportunity cost of putting so many batteries on a EV semi vs. a small fleet of hybrid commercial vans more than blows the comparison in favor of hybrids.

tonmoy 3y ago
We need to go to net zero somehow. With carbon capture or carbon offset technologies near non existing, we have to make the switch sooner or later
- jojobas 3y ago
  Trains.
  - DaiPlusPlus 3y ago
    Ideally, yes - but the US is lacking in rail infrastructure, so the US *needs* zero-emission, road-based, logistics solutions. (Disclaimer: Non-expert, but Tesla owner since Q1 2018) I think EV trucks, as a concept is fine, but battery-swapping makes much more sense than using a nonremovable battery-pack that's 5-10x the size of a sedan-sized battery-pack.
    - jojobas 3y ago
      Then rebuild the infrastructure. Wikipedia lists 100+ closed rail lines in the US, so the real count must be in thousands. Long haul should never be by road.
    - nradov 3y ago
      This article is about semi trucks. The US already has pretty much the best freight rail infrastructure in the world. Some further expansion is possible. But freight trains can't run everywhere, or handle highly perishable cargo, so the need for semi trucks can't be reduced much.
    - jcranmer 3y ago
      > Ideally, yes - but the US is lacking in rail infrastructure, so the US needs zero-emission, road-based, logistics solutions. Are you aware that the US has the largest rail network of any country in the world, almost the size of the next two (both of whom are geographically larger than the US) combined?
      - DaiPlusPlus 3y ago
        > Are you aware that the US has the largest rail network of any country in the world, almost the size of the next two (both of whom are geographically larger than the US) combined? Well of course, the US is a big country - but the overall density of rail (both freight and passenger rail) is lacking compared to Europe (and China too, I think?). I live in the Seattle metro area where the major cities (Everett, Seattle, and Tacoma) do have adequate freight rail accessibility, but none of the smaller and medium sized towns and cities elsewhere in the metro have any kind of rail connection to that main west-coast rail corridor, so they're reliant on road trucks to move goods in/out of those larger cities. ...whereas my part of the north-west of the UK (where I try to spend a good chunk of the year, where-possible) has rail connections between practically every small town, even many (most?) hamlets. Even local supermarkets use the rail network: https://www.railfreight.com/railfreight/2022/01/21/tesco-and-direct-rail-services-renew-supermarket-partnership/ https://www.railfreight.com/railfreight/2022/01/21/tesco-and...
        jcranmer 3y ago
        If you measure by mode share, the US railroad industry actually has a higher mode share than most European countries. The main issue with the freight rail industry in the US is that it's over-optimizing for the ultra-long-haul extreme bulk delivery--essentially acting as extensions of ports 1000's of miles inland--and abandoning local freight (where you drop off a car or two once a month or so) in the process. But that's not really caused by lack of rail infrastructure, which was your original complaint.
        ianburrell 3y ago
        The ideal would be electrified trains for long distance, and battery semis for local. The rail companies have not been looking after their infrastructure since they are cutting costs heavily. I read that one reason for Amtrak's poor performance is that freight railroads have single-tracked lines and removed passing sections leading to passenger trains stuck by freight trains.
    - RecycledEle 3y ago
      > the US needs zero-emission, road-based, logistics solutions. I worked on a SAE HEV Challenge car back in the 1990's. There is no such thing as a zero-emissions transportation solution. Let's say you managed to make a solar-powered skateboard navigate existing sidewalks and deliver packages. (Which is not going to happen.) You would still need to build the solar cells and computer boards, which are NOT zero-emissions processes. If an electric car is zero-emissions when running on battery power, my pickup is zero-emissions if I turn off the engine and coast down hill. Zero-emissions is nonsense. We can reduce emissions by reducing, reusing, and recycling. The problem is that our EPA overlords hate reusing. If they wanted to reduce emissions, they would not pull old vehicles off the road. Instead they would find low-use situations where they could replace newer vehicles. Instead they destroyed the oldest, most useful trucks in Junker-Clunker. This reminds me of a coworker / boss at a university I taught at about 10-15 years ago. She had a shiny new Lexus thing that got 15 MPG with a huge engine and an (I think) 8-speed automatic transmission when I had never seen such a thing before. (I know they are common now, but at the time that was odd.) She made fun of my old 1990's Chevy S10 pickup truck that got 25 MPG every time I drove 90 minutes each way to take 1,000 lbs of computer equipment to a recycling center. I only took in for recycling the stuff I could not reuse. Enviromentalism is all about looks. It has nothing to do with reducing emissions. If anyone believed the claims of the enviromentalists, they would be calling for the executions of the scum who cheat on fake carbon credits. Instead they are buying ocean front properties while selling books about rising sea levels.
      - thsksbd 3y ago
        You're right of course. 90% of environmentalism is virtue signaling. Anyone with a strong grasp of high school science snd math can figure that out. Easiest way to slash CO2 emissions literally overnight? Enforce speed limits, fuel consumption per trip scales (in the countryside) as v^2. EVs? A nasty joke anyone able to grasp opportunity cost can understand. If we really wanted to slash CO2 consumption we'd: - lower speed limits - Encourage delivery and contractor vehicles to go hybrid - Since we've slashed vehicle speeds, lower safety standards - Encourage motorcycle licensing (and promote motorcycle EVs. The only EVs that make sense) - Force manufacturers to provide information, tooling and parts to keep vehicles on the road longer - Encourage CNG LPG conversions Etc.
  - pardoned_turkey 3y ago
    The vast majority of trains in the US are diesel-powered, although they're about 4x more efficient than trucks. It's tempting to imagine they could all run on electricity, but it's probably hard, as many routes go through hundreds of miles of rugged nothingness. This is quite different from rail transport in Europe.
    - jojobas 3y ago
      There are very few places in the US that don't have 115kV+ lines somewhere nearby. http://www.geni.org/globalenergy/library/national_energy_grid/united-states-of-america/americannationalelectricitygrid.shtml http://www.geni.org/globalenergy/library/national_energy_gri... They follow the same valleys around heavy terrain etc. Feel free to superimpose the grid map and the rail map. So it's a matter of electric locomotives, poles, contact wires and transformers, no small feat but what can you do.
      - ianburrell 3y ago
        The rail companies are really resistant to electrifying lines. I think because they are focused on cutting costs and spending money would cut into profit. Unfortunately, that means that the government will likely have to pay for it or force them. They have been looking into battery electric locomotives which don't make any sense except for switching yards. I read recently that there are electric and diesel locomotives which can use overhead power where available and switch to diesel when it isn't. That has the advantage that they can electrify lines incrementally.
    - peteradio 3y ago
      Yea and what if a little kid stepped on the track and got electrifried. But at least if it got hit by a lightning it would get some free juice so there's plussed and minused.
- 01100011 3y ago
  "We" (the west) need to go below net zero as it's clear that most of the world isn't concerned with curbing carbon emissions(quite the opposite, it seems). Note that "need" here is in the context of meeting the climate goals we've chosen to impose on ourselves. I'm not going to debate the wisdom of that choice here.
  - junofan 3y ago
    I haven’t heard the Saudis say they will cap their wells when we stop paying them.
    - _aavaa_ 3y ago
      The problem isn’t pumping oil out of the ground, it’s burning it and putting the rest in the atmosphere. Treating oil as a feedstock to other products which ultimately do not end up in the atmosphere should be thought of just like any other resource we extract from the ground.
- HorizonXP 3y ago
  But the current manufacturing of EVs and batteries isn’t carbon neutral or net zero until well into a vehicle’s lifecycle. It’s still worth doing but we should understand the true cost.
  - davely 3y ago
    I mean, the true cost is that EVs will eventually get to net zero during their lifetime. ICE never will.
  - D-Coder 3y ago
    Manufacturing diesel fuel isn't carbon neutral either. At any point in the vehicle's lifecycle.
    - HorizonXP 3y ago
      Fair!
- deleted 3y ago
  [deleted]
- revscat 3y ago
  Have to, or perish. The smart money is on perishing.
  - junofan 3y ago
    I think biodiesel adoption is more likely than the extinction of our species.
  - datadrivenangel 3y ago
    Not everyone perishes, just a few hundred extra million deaths per degree Celsius? Very very bad, but not everyone.
- rr808 3y ago
  Hydrogen.
- wpm 3y ago
  Something like only 20-25% of carbon emissions in the US are from freight. The vast majority come from personal transportation. Ditch your car.
  - me_me_me 3y ago
    Ditch your car. Ok, how? In Americas case you might aswell shout yourself. As you cannot live without a car. Saying Ditch your car is as good solution as 'Just stop breathing in pollution'.
- thsksbd 3y ago
  Even if I concede your premise that our pressing need to decarburize, I am not clear what it is you are proposing. Surely not fast EV adoption! I specifically point out that rapid adoption of EVs at the expense of hybrids given limited batteries is slowing the decarbonization of the transportation sector even if we assume EVs run on fairies' farts This is because an EV has many many times more batteries than a hybrid, so (if you do the math) it ends up being much worse to run EVs even assuming their energy doesnt come from anywhere than it is to replace regular cars with hybrids.
ReactiveJelly 3y ago
Priuses manage to get 50 mpg highway without depleting charge or plugging in but I guess the same optimizations can't work on a big diesel as on a little gas engine?
- borner791 3y ago
  Prius is just a little gas engine in a little and aerodynamic car. They can have a tiny gas engine because the electric helps acceleration from a standstill. The batteries are just weight on the highway
  - adfiogn1i2o 3y ago
    The Prius is not especially small. The engine is 2.0 liters, which is not small at all. It is much more sophisticated than you let on.
  - jojobas 3y ago
    >The batteries are just weight on the highway Not quite. Diesel engines are most efficient (~40%) at full throttle, low-mid revs, and drop to <30% at low throttle. With some battery trashing you could see the engine work at some 20-50% duty cycle on the highway.
    - thsksbd 3y ago
      Not quite. otto cycle is most efficient at full throttle due to throttle valve pump losses. Diesels are most thermodynamically efficient at low throttle because it takes time to combust the fuel. During this time the piston expands and the compression ratio drops. You can see the derivation and formulas in Faires (and older edition. Even the 70s edition lacked the chapter). Actually just comparing the the PV diagram of otto and diesel makes it obvious.
      - jacquesm 3y ago
        > Diesels are most thermodynamically efficient at low throttle I think you meant 'low RPM'. Low throttle doesn't always equate low RPM and VV.
thelastgallon 3y ago
Its a lot easier than you think. Just like trains, but on roads. The highway where trucks work like electric trains: https://www.youtube.com/watch?v=_3P_S7pL7Yg https://www.youtube.com/watch?v=_3P_S7pL7Yg And, there is electrification happening along highways, producing energy. German highway PV could generate up to 200 TWh a year: https://www.pv-magazine.com/2023/04/11/german-highway-pv-could-generate-up-to-200-twh-a-year/ https://www.pv-magazine.com/2023/04/11/german-highway-pv-cou... Also, battery swapping will become a thing. You don't have to haul a ton of batteries, you can swap them in seconds along your route. There will be (eventually) a ton of battery plants replacing peaker natural gas plants, these will be built along the highways, also serving a second function of battery swap stations.
- deleted 3y ago
  [deleted]
- chis 3y ago
  Electrified highways is a super interesting idea. In this video they're hybrids though - presumably they come up to speed with combustion and then just use the grid for cruising. And I don't think it's a huge cost to have a gas and electric motor anyways, it's certainly not as heavy as a 1000KWH battery.
- clouddrover 3y ago
  > Also, battery swapping will become a thing. Already is a thing for trucks: https://www.youtube.com/watch?v=9eYLtPSf7PY https://www.youtube.com/watch?v=9eYLtPSf7PY Janus Trucks converts your existing trucks to battery electric and provides swap stations.
- thsksbd 3y ago
  This is about large battery powered EVs, not grid powered ones. Also, it doesnt matter if you can swap a battery, or charge a fixed one in a microsecond. the problem is the opportunity cost of using a lot of battery to electrify one vehicle instead of hybridizing many more EVs by taking away batteries from hybrids are bad.
  - 3y ago
wilg 3y ago
Hybrids don't solve the problem, you need zero-emission. This is for long-distance hauling.
- thsksbd 3y ago
  Which problem? Please be more clear, more specific instead of using slogans. As I understand you want to cut emissions, reduce it to zero. Fine. EV vehicles generally, and EV semis in particular, are a massive impediment to the rapid decarbonization of the transportation sector. Why? 1. A large EV semi has a gargantuan amount of batteries. 2. Batteries are a finite resource, limited by our ability to produce them. 3. Semi engines are very fuel efficient, as far as thermal cycles go. 4. Cities have very many, very inefficient small vehicles undergoing start-stop cycles Most of these vehicles run on straight gasoline. 5. More carbon can be taken off our transportation network by keeping diesel semis and using the batteries an EV semi would have used to hybridize vehicular traffic. Go ahead, do the math and see that N5 is correct. For representative numbers compare the F150 that comes in regular, hybrid and EV. When opportunity costs are considered, the hybrid F150 kicks the teeth out of the EV one in carbon emissions.
  - wilg 3y ago
    One zero emission truck is worth about 40 zero emission cars in terms of grams of CO2e. And diesel trucks cannot go zero emission. So this makes no sense to me.
    - thsksbd 3y ago
      Well, what can I say? Do the math! One EV truck = x amount of batteries. Per the article, 700kWh One F150 hybrid [1] = y amount of batteries. Per Ford, 1.5 kWh [2] One EV truck = x/y F150 hybrids, or 500 pickup trucks. 500 hybrids pickups are sacrificed to make one Tesla EV semi. Now, look up the amount of miles driven by your average delivery guy. This guy probably has the worst fuel situation on the road. Heavy vehicle. Stop and go. Urban. I'll be nice and assume 15000mi, what the DOE estimates for the average commuter Subtract fuel consumed by Amazon guy on regular F150 (18mpg) vs hybrid F150 (25 mpg) on 15000 miles. 233 gallons. Multiply by x/y. 500x233 This is the fuel saved by hybridizing. 116 000 gal 116 000 gallons of fuel. I actually didn't believe this, so i did the math twice. A YEAR In a year, on average, a semi goes through just less than 10 000 gallons of fuel. [3] So the single EV truck costs 11X more fuel than the fleet of 500 delivery vehicles that could been built with its battery pack. Note, that this analysis is incredibly favorable to the EV semi as it assumes there is no CO2 emission from charging it. The batteries magically recharge. This is grossly untrue. Nor am I considering that truck batteries aren't going to last very long. [1] F150 is used because it comes in regular, hybrid and EV trim, and is roughly the size category that an amazon or FedEx delivery truck. [2] https://www.ford.com/cmslibs/content/dam/brand_ford/en_us/brand/trucks/f150/2020/Mediakit/F_150_PowerBoost_Graphic_1_1.pdf https://www.ford.com/cmslibs/content/dam/brand_ford/en_us/br... [3] https://www.truckinfo.net/research/trucking-statistics https://www.truckinfo.net/research/trucking-statistics*

tonmoy 3y ago

We need to go to net zero somehow. With carbon capture or carbon offset technologies near non existing, we have to make the switch sooner or later

jojobas 3y ago
Trains.
- DaiPlusPlus 3y ago
  Ideally, yes - but the US is lacking in rail infrastructure, so the US *needs* zero-emission, road-based, logistics solutions. (Disclaimer: Non-expert, but Tesla owner since Q1 2018) I think EV trucks, as a concept is fine, but battery-swapping makes much more sense than using a nonremovable battery-pack that's 5-10x the size of a sedan-sized battery-pack.
  - jojobas 3y ago
    Then rebuild the infrastructure. Wikipedia lists 100+ closed rail lines in the US, so the real count must be in thousands. Long haul should never be by road.
  - nradov 3y ago
    This article is about semi trucks. The US already has pretty much the best freight rail infrastructure in the world. Some further expansion is possible. But freight trains can't run everywhere, or handle highly perishable cargo, so the need for semi trucks can't be reduced much.
  - jcranmer 3y ago
    > Ideally, yes - but the US is lacking in rail infrastructure, so the US needs zero-emission, road-based, logistics solutions. Are you aware that the US has the largest rail network of any country in the world, almost the size of the next two (both of whom are geographically larger than the US) combined?
    - DaiPlusPlus 3y ago
      > Are you aware that the US has the largest rail network of any country in the world, almost the size of the next two (both of whom are geographically larger than the US) combined? Well of course, the US is a big country - but the overall density of rail (both freight and passenger rail) is lacking compared to Europe (and China too, I think?). I live in the Seattle metro area where the major cities (Everett, Seattle, and Tacoma) do have adequate freight rail accessibility, but none of the smaller and medium sized towns and cities elsewhere in the metro have any kind of rail connection to that main west-coast rail corridor, so they're reliant on road trucks to move goods in/out of those larger cities. ...whereas my part of the north-west of the UK (where I try to spend a good chunk of the year, where-possible) has rail connections between practically every small town, even many (most?) hamlets. Even local supermarkets use the rail network: https://www.railfreight.com/railfreight/2022/01/21/tesco-and-direct-rail-services-renew-supermarket-partnership/ https://www.railfreight.com/railfreight/2022/01/21/tesco-and...
      - jcranmer 3y ago
        If you measure by mode share, the US railroad industry actually has a higher mode share than most European countries. The main issue with the freight rail industry in the US is that it's over-optimizing for the ultra-long-haul extreme bulk delivery--essentially acting as extensions of ports 1000's of miles inland--and abandoning local freight (where you drop off a car or two once a month or so) in the process. But that's not really caused by lack of rail infrastructure, which was your original complaint.
        ianburrell 3y ago
        The ideal would be electrified trains for long distance, and battery semis for local. The rail companies have not been looking after their infrastructure since they are cutting costs heavily. I read that one reason for Amtrak's poor performance is that freight railroads have single-tracked lines and removed passing sections leading to passenger trains stuck by freight trains.
  - RecycledEle 3y ago
    > the US needs zero-emission, road-based, logistics solutions. I worked on a SAE HEV Challenge car back in the 1990's. There is no such thing as a zero-emissions transportation solution. Let's say you managed to make a solar-powered skateboard navigate existing sidewalks and deliver packages. (Which is not going to happen.) You would still need to build the solar cells and computer boards, which are NOT zero-emissions processes. If an electric car is zero-emissions when running on battery power, my pickup is zero-emissions if I turn off the engine and coast down hill. Zero-emissions is nonsense. We can reduce emissions by reducing, reusing, and recycling. The problem is that our EPA overlords hate reusing. If they wanted to reduce emissions, they would not pull old vehicles off the road. Instead they would find low-use situations where they could replace newer vehicles. Instead they destroyed the oldest, most useful trucks in Junker-Clunker. This reminds me of a coworker / boss at a university I taught at about 10-15 years ago. She had a shiny new Lexus thing that got 15 MPG with a huge engine and an (I think) 8-speed automatic transmission when I had never seen such a thing before. (I know they are common now, but at the time that was odd.) She made fun of my old 1990's Chevy S10 pickup truck that got 25 MPG every time I drove 90 minutes each way to take 1,000 lbs of computer equipment to a recycling center. I only took in for recycling the stuff I could not reuse. Enviromentalism is all about looks. It has nothing to do with reducing emissions. If anyone believed the claims of the enviromentalists, they would be calling for the executions of the scum who cheat on fake carbon credits. Instead they are buying ocean front properties while selling books about rising sea levels.
    - thsksbd 3y ago
      You're right of course. 90% of environmentalism is virtue signaling. Anyone with a strong grasp of high school science snd math can figure that out. Easiest way to slash CO2 emissions literally overnight? Enforce speed limits, fuel consumption per trip scales (in the countryside) as v^2. EVs? A nasty joke anyone able to grasp opportunity cost can understand. If we really wanted to slash CO2 consumption we'd: - lower speed limits - Encourage delivery and contractor vehicles to go hybrid - Since we've slashed vehicle speeds, lower safety standards - Encourage motorcycle licensing (and promote motorcycle EVs. The only EVs that make sense) - Force manufacturers to provide information, tooling and parts to keep vehicles on the road longer - Encourage CNG LPG conversions Etc.
- pardoned_turkey 3y ago
  The vast majority of trains in the US are diesel-powered, although they're about 4x more efficient than trucks. It's tempting to imagine they could all run on electricity, but it's probably hard, as many routes go through hundreds of miles of rugged nothingness. This is quite different from rail transport in Europe.
  - jojobas 3y ago
    There are very few places in the US that don't have 115kV+ lines somewhere nearby. http://www.geni.org/globalenergy/library/national_energy_grid/united-states-of-america/americannationalelectricitygrid.shtml http://www.geni.org/globalenergy/library/national_energy_gri... They follow the same valleys around heavy terrain etc. Feel free to superimpose the grid map and the rail map. So it's a matter of electric locomotives, poles, contact wires and transformers, no small feat but what can you do.
    - ianburrell 3y ago
      The rail companies are really resistant to electrifying lines. I think because they are focused on cutting costs and spending money would cut into profit. Unfortunately, that means that the government will likely have to pay for it or force them. They have been looking into battery electric locomotives which don't make any sense except for switching yards. I read recently that there are electric and diesel locomotives which can use overhead power where available and switch to diesel when it isn't. That has the advantage that they can electrify lines incrementally.
  - peteradio 3y ago
    Yea and what if a little kid stepped on the track and got electrifried. But at least if it got hit by a lightning it would get some free juice so there's plussed and minused.
01100011 3y ago
"We" (the west) need to go below net zero as it's clear that most of the world isn't concerned with curbing carbon emissions(quite the opposite, it seems). Note that "need" here is in the context of meeting the climate goals we've chosen to impose on ourselves. I'm not going to debate the wisdom of that choice here.
- junofan 3y ago
  I haven’t heard the Saudis say they will cap their wells when we stop paying them.
  - _aavaa_ 3y ago
    The problem isn’t pumping oil out of the ground, it’s burning it and putting the rest in the atmosphere. Treating oil as a feedstock to other products which ultimately do not end up in the atmosphere should be thought of just like any other resource we extract from the ground.
HorizonXP 3y ago
But the current manufacturing of EVs and batteries isn’t carbon neutral or net zero until well into a vehicle’s lifecycle. It’s still worth doing but we should understand the true cost.
- davely 3y ago
  I mean, the true cost is that EVs will eventually get to net zero during their lifetime. ICE never will.
- D-Coder 3y ago
  Manufacturing diesel fuel isn't carbon neutral either. At any point in the vehicle's lifecycle.
  - HorizonXP 3y ago
    Fair!
deleted 3y ago
[deleted]
revscat 3y ago
Have to, or perish. The smart money is on perishing.
- junofan 3y ago
  I think biodiesel adoption is more likely than the extinction of our species.
- datadrivenangel 3y ago
  Not everyone perishes, just a few hundred extra million deaths per degree Celsius? Very very bad, but not everyone.
rr808 3y ago
Hydrogen.
wpm 3y ago
Something like only 20-25% of carbon emissions in the US are from freight. The vast majority come from personal transportation. Ditch your car.
- me_me_me 3y ago
  Ditch your car. Ok, how? In Americas case you might aswell shout yourself. As you cannot live without a car. Saying Ditch your car is as good solution as 'Just stop breathing in pollution'.
thsksbd 3y ago
Even if I concede your premise that our pressing need to decarburize, I am not clear what it is you are proposing. Surely not fast EV adoption! I specifically point out that rapid adoption of EVs at the expense of hybrids given limited batteries is slowing the decarbonization of the transportation sector even if we assume EVs run on fairies' farts This is because an EV has many many times more batteries than a hybrid, so (if you do the math) it ends up being much worse to run EVs even assuming their energy doesnt come from anywhere than it is to replace regular cars with hybrids.

ReactiveJelly 3y ago

Priuses manage to get 50 mpg highway without depleting charge or plugging in but I guess the same optimizations can't work on a big diesel as on a little gas engine?

borner791 3y ago
Prius is just a little gas engine in a little and aerodynamic car. They can have a tiny gas engine because the electric helps acceleration from a standstill. The batteries are just weight on the highway
- adfiogn1i2o 3y ago
  The Prius is not especially small. The engine is 2.0 liters, which is not small at all. It is much more sophisticated than you let on.
- jojobas 3y ago
  >The batteries are just weight on the highway Not quite. Diesel engines are most efficient (~40%) at full throttle, low-mid revs, and drop to <30% at low throttle. With some battery trashing you could see the engine work at some 20-50% duty cycle on the highway.
  - thsksbd 3y ago
    Not quite. otto cycle is most efficient at full throttle due to throttle valve pump losses. Diesels are most thermodynamically efficient at low throttle because it takes time to combust the fuel. During this time the piston expands and the compression ratio drops. You can see the derivation and formulas in Faires (and older edition. Even the 70s edition lacked the chapter). Actually just comparing the the PV diagram of otto and diesel makes it obvious.
    - jacquesm 3y ago
      > Diesels are most thermodynamically efficient at low throttle I think you meant 'low RPM'. Low throttle doesn't always equate low RPM and VV.

thelastgallon 3y ago

Its a lot easier than you think. Just like trains, but on roads. The highway where trucks work like electric trains: https://www.youtube.com/watch?v=_3P_S7pL7Yg https://www.youtube.com/watch?v=_3P_S7pL7Yg And, there is electrification happening along highways, producing energy. German highway PV could generate up to 200 TWh a year: https://www.pv-magazine.com/2023/04/11/german-highway-pv-could-generate-up-to-200-twh-a-year/ https://www.pv-magazine.com/2023/04/11/german-highway-pv-cou... Also, battery swapping will become a thing. You don't have to haul a ton of batteries, you can swap them in seconds along your route. There will be (eventually) a ton of battery plants replacing peaker natural gas plants, these will be built along the highways, also serving a second function of battery swap stations.

deleted 3y ago
[deleted]
chis 3y ago
Electrified highways is a super interesting idea. In this video they're hybrids though - presumably they come up to speed with combustion and then just use the grid for cruising. And I don't think it's a huge cost to have a gas and electric motor anyways, it's certainly not as heavy as a 1000KWH battery.
clouddrover 3y ago
> Also, battery swapping will become a thing. Already is a thing for trucks: https://www.youtube.com/watch?v=9eYLtPSf7PY https://www.youtube.com/watch?v=9eYLtPSf7PY Janus Trucks converts your existing trucks to battery electric and provides swap stations.
thsksbd 3y ago
This is about large battery powered EVs, not grid powered ones. Also, it doesnt matter if you can swap a battery, or charge a fixed one in a microsecond. the problem is the opportunity cost of using a lot of battery to electrify one vehicle instead of hybridizing many more EVs by taking away batteries from hybrids are bad.
- 3y ago

wilg 3y ago

Hybrids don't solve the problem, you need zero-emission. This is for long-distance hauling.

thsksbd 3y ago
Which problem? Please be more clear, more specific instead of using slogans. As I understand you want to cut emissions, reduce it to zero. Fine. EV vehicles generally, and EV semis in particular, are a massive impediment to the rapid decarbonization of the transportation sector. Why? 1. A large EV semi has a gargantuan amount of batteries. 2. Batteries are a finite resource, limited by our ability to produce them. 3. Semi engines are very fuel efficient, as far as thermal cycles go. 4. Cities have very many, very inefficient small vehicles undergoing start-stop cycles Most of these vehicles run on straight gasoline. 5. More carbon can be taken off our transportation network by keeping diesel semis and using the batteries an EV semi would have used to hybridize vehicular traffic. Go ahead, do the math and see that N5 is correct. For representative numbers compare the F150 that comes in regular, hybrid and EV. When opportunity costs are considered, the hybrid F150 kicks the teeth out of the EV one in carbon emissions.
- wilg 3y ago
  One zero emission truck is worth about 40 zero emission cars in terms of grams of CO2e. And diesel trucks cannot go zero emission. So this makes no sense to me.
  - thsksbd 3y ago
    Well, what can I say? Do the math! One EV truck = x amount of batteries. Per the article, 700kWh One F150 hybrid [1] = y amount of batteries. Per Ford, 1.5 kWh [2] One EV truck = x/y F150 hybrids, or 500 pickup trucks. 500 hybrids pickups are sacrificed to make one Tesla EV semi. Now, look up the amount of miles driven by your average delivery guy. This guy probably has the worst fuel situation on the road. Heavy vehicle. Stop and go. Urban. I'll be nice and assume 15000mi, what the DOE estimates for the average commuter Subtract fuel consumed by Amazon guy on regular F150 (18mpg) vs hybrid F150 (25 mpg) on 15000 miles. 233 gallons. Multiply by x/y. 500x233 This is the fuel saved by hybridizing. 116 000 gal 116 000 gallons of fuel. I actually didn't believe this, so i did the math twice. A YEAR In a year, on average, a semi goes through just less than 10 000 gallons of fuel. [3] So the single EV truck costs 11X more fuel than the fleet of 500 delivery vehicles that could been built with its battery pack. Note, that this analysis is incredibly favorable to the EV semi as it assumes there is no CO2 emission from charging it. The batteries magically recharge. This is grossly untrue. Nor am I considering that truck batteries aren't going to last very long. [1] F150 is used because it comes in regular, hybrid and EV trim, and is roughly the size category that an amazon or FedEx delivery truck. [2] https://www.ford.com/cmslibs/content/dam/brand_ford/en_us/brand/trucks/f150/2020/Mediakit/F_150_PowerBoost_Graphic_1_1.pdf https://www.ford.com/cmslibs/content/dam/brand_ford/en_us/br... [3] https://www.truckinfo.net/research/trucking-statistics https://www.truckinfo.net/research/trucking-statistics*