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Fast charge speeds make electrified highways a more viable option. There are some projects in Europe using overhead lines (for trucks) or power rails embedded

by elihu 2y ago

Fast charge speeds make electrified highways a more viable option. There are some projects in Europe using overhead lines (for trucks) or power rails embedded in slots in the road surface (usable by cars or trucks) so that vehicles can recharge while moving. Building a network of electrified highways is expensive though. One way to reduce initial costs is not to electrify the whole length but to have, say, one mile of electrified road per every ten miles of highway. To get unlimited range from that 1:10 ratio, you need the vehicles to have batteries capable of absorbing power 9x faster than the vehicle uses it to maintain highway speeds. I could see EVs having a large lithium ion pack and, if this technology is really that good, a smaller sodium ion battery to act sort of like a capacitor to smooth out intermittent charging. I could also see low-capacity-high-power-density batteries being used in hybrids, though those need to be able to sustain high discharge rates as well as high charge rates, and I don't think the article mentioned discharge rates.

dieortin 2y ago
Charging private vehicles while they move sounds very complicated
- elihu 2y ago
  This is one way to do it: https://www.theguardian.com/environment/2018/apr/12/worlds-first-electrified-road-for-charging-vehicles-opens-in-sweden https://www.theguardian.com/environment/2018/apr/12/worlds-f... Overhead cables are simpler and cheaper, but not easily compatible with cars (which would need a comically tall pantograph to connect to the cables). (Induction is a third option, but it's not really viable except in certain special cases because it's way more expensive, can't deliver as much power, and tends to be less energy efficient.) Electrifying highways may sound expensive or complicated, but consider what the alternatives are. We could stick with fossil fuels. The U.S. burns about 4 million barrels of gasoline and about 4 million barrels of diesel a day, most of which is used to push cars and trucks around. That's not simple or cheap, we're just accustomed to the cost. Another option is we switch to EVs and rely on big batteries for range. That kind of works, but battery manufacturing scale isn't there. It's also kind of wasteful to have a substantial portion of the vehicle weight being batteries. It means cars and trucks are heavier than they need to be, and they can haul less cargo. If we could get to the point where, say, someone could drive coast-to-coast without ever having to stop to charge with only 30 or 40 kwh battery, that would be huge. It would reduce EV costs dramatically, it would reduce average vehicle weight, and you might even get better performance. (This wouldn't completely eliminate the need for some long-range vehicles for areas not served by electrified highways, but for most uses it should be fine.)
- bufferoverflow 2y ago
  Trolleybus is a technology from over 100 year ago.
  - kube-system 2y ago
    Yes, but a primary advantage to private transportation is the ability to drive it in locations other than predefined routes in dense city centers.
    - elihu 2y ago
      I think the point they were making is that a suitable technology to deliver power to a moving vehicle has been around a long time, not that everyone should get rid of their cars and use trolleys. If we combine a modern EV with 100 year old tram technology, you get the ability for a car to charge itself when travelling on roads that have a compatible system of overhead power lines. Having a huge pantograph on top of the car is kind of impractical, but powering cars from underneath via power rails embedded in slots in the road, like a full-sized version of those toy slot cars that used to be popular, is another option that's been tried on some roads in Sweden.
      - kube-system 2y ago
        My point is that those solutions are impractical for any sort of widespread use.
        elihu 2y ago
        Impractical compared to what? The U.S. burns about 4 million barrels of gasoline and about the same amount of diesel per day, mostly just pushing ground vehicles around. That sort of works, but I wouldn't call it practical in the long run. Converting to EVs is the obvious alternative, but batteries are expensive and we haven't scaled up battery manufacturing yet to the degree necessary to replace ICE vehicles. We can get more EVs on the road though if the average EV can get by with a much smaller battery. On some level it's an optimization problem: using the U.S. as an example, there are about 280 million cars/trucks currently registered. Is it cheaper/better to build about 280 million EVs with about 60kwh of batteries each on average, or build 280 million EVs with about 30kwh of batteries each and electrify our major highways? If batteries cost $100/kwh, then 280 million * $100 * 30 = 840 billion dollars. If electrifying the major highways can be done for under $840 billion dollars, then it makes sense to do. The interstate highway system is about 50,000 miles. Sweden spent about a million euros per kilometer to electrify a section of road using the slot-embedded-in-the-road system. That's about $1.7 million per mile, or $86.5 billion. You'd probably need to do more than just the interstates, but then at the same time you don't need to electrify 100% of the length of those highways. Maybe just 10% or 20%, as long as electrified section come at regular intervals. This is all kind of simplistic and hand-wavey, but it seems like it passes the threshold of "we should at least consider doing this."
theendisney 2y ago
imagine this! Have short charging strips at traffic lights then prioritize lanes with cars that dont need much charge.
- elihu 2y ago
  That's an option, though I think the amount of time cars spend at stop lights is so highly variable that it'd be hard to make that practical. Also, in-town driving is usually short range anyways. For that, having a 100 mile or even a 50 mile battery is plenty, and people can charge overnight at home. (And yes, ideally apartments ought to have EV charging stations.) Where people are more likely to need the extra charge is on the long country roads between major cities. Probably a high priority could be on the major highways going into and out of cities, as those are the roads people are likely to use for long daily commutes.
  - theendisney 2y ago
    There are so many options. Things will just have to be tried until the best marketing formula wins. I really have dozens of strange ideas. If the charging stations need to be equiped with similar batteries we might as well make all cars into charging stations. You can charge your much to large 3x per year road trip battery with your much to large solar array. Park it some place (preferably in need), flag the car in the app as wont move for x hours and has y kwh availble then charge your 40km range coworker premium tarif while you work. A rail with a towing cable could also charge batteries while also usable for ic engines.

by elihu 2y ago

dieortin 2y ago

Charging private vehicles while they move sounds very complicated

elihu 2y ago
This is one way to do it: https://www.theguardian.com/environment/2018/apr/12/worlds-first-electrified-road-for-charging-vehicles-opens-in-sweden https://www.theguardian.com/environment/2018/apr/12/worlds-f... Overhead cables are simpler and cheaper, but not easily compatible with cars (which would need a comically tall pantograph to connect to the cables). (Induction is a third option, but it's not really viable except in certain special cases because it's way more expensive, can't deliver as much power, and tends to be less energy efficient.) Electrifying highways may sound expensive or complicated, but consider what the alternatives are. We could stick with fossil fuels. The U.S. burns about 4 million barrels of gasoline and about 4 million barrels of diesel a day, most of which is used to push cars and trucks around. That's not simple or cheap, we're just accustomed to the cost. Another option is we switch to EVs and rely on big batteries for range. That kind of works, but battery manufacturing scale isn't there. It's also kind of wasteful to have a substantial portion of the vehicle weight being batteries. It means cars and trucks are heavier than they need to be, and they can haul less cargo. If we could get to the point where, say, someone could drive coast-to-coast without ever having to stop to charge with only 30 or 40 kwh battery, that would be huge. It would reduce EV costs dramatically, it would reduce average vehicle weight, and you might even get better performance. (This wouldn't completely eliminate the need for some long-range vehicles for areas not served by electrified highways, but for most uses it should be fine.)
bufferoverflow 2y ago
Trolleybus is a technology from over 100 year ago.
- kube-system 2y ago
  Yes, but a primary advantage to private transportation is the ability to drive it in locations other than predefined routes in dense city centers.
  - elihu 2y ago
    I think the point they were making is that a suitable technology to deliver power to a moving vehicle has been around a long time, not that everyone should get rid of their cars and use trolleys. If we combine a modern EV with 100 year old tram technology, you get the ability for a car to charge itself when travelling on roads that have a compatible system of overhead power lines. Having a huge pantograph on top of the car is kind of impractical, but powering cars from underneath via power rails embedded in slots in the road, like a full-sized version of those toy slot cars that used to be popular, is another option that's been tried on some roads in Sweden.
    - kube-system 2y ago
      My point is that those solutions are impractical for any sort of widespread use.
      - elihu 2y ago
        Impractical compared to what? The U.S. burns about 4 million barrels of gasoline and about the same amount of diesel per day, mostly just pushing ground vehicles around. That sort of works, but I wouldn't call it practical in the long run. Converting to EVs is the obvious alternative, but batteries are expensive and we haven't scaled up battery manufacturing yet to the degree necessary to replace ICE vehicles. We can get more EVs on the road though if the average EV can get by with a much smaller battery. On some level it's an optimization problem: using the U.S. as an example, there are about 280 million cars/trucks currently registered. Is it cheaper/better to build about 280 million EVs with about 60kwh of batteries each on average, or build 280 million EVs with about 30kwh of batteries each and electrify our major highways? If batteries cost $100/kwh, then 280 million * $100 * 30 = 840 billion dollars. If electrifying the major highways can be done for under $840 billion dollars, then it makes sense to do. The interstate highway system is about 50,000 miles. Sweden spent about a million euros per kilometer to electrify a section of road using the slot-embedded-in-the-road system. That's about $1.7 million per mile, or $86.5 billion. You'd probably need to do more than just the interstates, but then at the same time you don't need to electrify 100% of the length of those highways. Maybe just 10% or 20%, as long as electrified section come at regular intervals. This is all kind of simplistic and hand-wavey, but it seems like it passes the threshold of "we should at least consider doing this."

theendisney 2y ago

imagine this! Have short charging strips at traffic lights then prioritize lanes with cars that dont need much charge.

elihu 2y ago
That's an option, though I think the amount of time cars spend at stop lights is so highly variable that it'd be hard to make that practical. Also, in-town driving is usually short range anyways. For that, having a 100 mile or even a 50 mile battery is plenty, and people can charge overnight at home. (And yes, ideally apartments ought to have EV charging stations.) Where people are more likely to need the extra charge is on the long country roads between major cities. Probably a high priority could be on the major highways going into and out of cities, as those are the roads people are likely to use for long daily commutes.
- theendisney 2y ago
  There are so many options. Things will just have to be tried until the best marketing formula wins. I really have dozens of strange ideas. If the charging stations need to be equiped with similar batteries we might as well make all cars into charging stations. You can charge your much to large 3x per year road trip battery with your much to large solar array. Park it some place (preferably in need), flag the car in the app as wont move for x hours and has y kwh availble then charge your 40km range coworker premium tarif while you work. A rail with a towing cable could also charge batteries while also usable for ic engines.