This is one way to do it:

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.)

Trolleybus is a technology from over 100 year 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.

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.

My point is that those solutions are impractical for any sort of widespread use.

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."

> 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.

Maybe you mean it isn't 'sustainable'? ICE vehicles are the epitome of practical, they are used in practice all around the world.

> 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%,

The people who developed that project estimated they'd need to implement it on 25% of all roads. Also the project is just in a technical demonstrator phase. It is literally just a tech demo, and there are still major concerns about adoption, implementation, and maintenance.

> 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."

I agree it should be tested further, but there are likely significant barriers that will prevent it from being useful, particularly in less dense areas.

The focus of the effort to make overhead charging viable is on large trucks that already drive mostly, but not completely, predefined routes on highways and in cities, which are often too lengthy to only rely on battery packs.

Others up above were discussing passenger vehicles.

For trucks on the highway, it is a much better idea, but for many of those cases, you'd be significantly better off investing in more rail.

Transporting refrigerated goods over moderate distances and last-mile delivery from the train yards are where trucks using overhead cables can shine. I also read that there existed trolleybus lines that went several miles/kilometers between towns that weren't connected by rail. It's especially useful in mountainous terrain.