The car and the road are actually parts of a giant dynamo, I guess. Like the car having a coil and under the road a giant magnet, thus generating current in the coil.
Nice idea.
Nice idea.
If you want to run the numbers yourself a Tesla uses 300 watt-hours per mile on the highway. California route 60 sees 337000 cars per day and is 70 miles long. And an amazing power transfer system might be 75% efficient.
Taking the thought to the extreme, it could also be used as a kind of traffic shaping/control system. Have some roads "energised" at specific times to provide an incentive to go a longer way to alleviate chokes or traffic jams.
That gives many people an incentive to take a longer path (whereas current systems/methods for this are kind of driver-hostile as the drivers going the longer route don't get any direct benefit)
And then... when Road v2.0 comes out and it all has to get replaced? v3.0? Then flying cars and no one uses roads?
337000 cars/day * 300Wh/mile/car * (1-.75) = 654W/m
So, I don't see the problem?
Along the length of the road, that is 21kWh. At 75% efficiency, that is 7kWh into the road surface per car. Roughly 2.4GWh of energy ($200k worth of electricity) per day lost as heat into the roadbed in total. Assuming 4 lanes and a 3.7m lane width, route 60 is 1.7 million square meters of asphalt and that is 1.4kWh per square meter. (8x more than your number.) Still comparable to solar irradiation though. Asphalt might get a little soft on a busy summer day when everyone is also running their AC but it wouldn't be a molten puddle. If the chargers are only embedded in a narrow strip down the middle of the lane, that section might get very soft.
So at 75% I guess it is practical. But 75% is going to be extremely hard. And the first place this should be installed is Route 1, because it would be a highway-sized snow-melter that also happens to power vehicles.
Now ask yourself why we don't have defrosted highways. Installing roadbed chargers is going to be even more difficult.
As a sanity check at highway speeds it takes ~30HP to maintain speed or a loss of 10HP or 7.5kw over ~60m (distance from one front bumper to next) x ~4m approximate width of a lane = 30w/meter which is a non issue. Lower speeds need less power, but can have more cars.
Further, not every car needs 100% power as batteries are still a thing, this is just for the subset of long distance traffic. And if you limit things to say 75% of a cars power demand that's still 4x the range.
I'm picturing future roads looking like massive Scalectrix tracks...
Also, the article is a lot more optimistic about efficiency:
"The group used an off-the-shelf, general-purpose amplifier with a relatively low efficiency of about 10 percent. They say custom-made amplifiers can improve that efficiency to more than 90 percent."
Correct me if I am wrong.