He talked about it a little bit in the video mentioned in the post. He thinks about "open sourcing"(his words) or patenting the idea and giving the patent to someone who has the financial resources to build it. I guess because of that he hasn't gone into much detail but here is a list of things about the Hyperloop I remembered:
-from downtown LA to downtown SF in 30 Minutes
-cheaper than airplane ticket
-solar panels on the top to make it self sustaining
-energy would be saved without batteries to run at night
-under no influence of the weather
-safe
(-Sarah Lacy made a reference to a TV show/movie with a tube as transportation system, and Elon said it was kind of like that [can't remember the title])
Because it's not subject to the rocket equation, it would basically have the same effect on space access costs as a space elevator.
It is possible in principle for such a device to bring a vehicle up to hypersonic speeds, then regeneratively brake the same vehicle to a stop and recover a fraction of the energy.
Good reading there, but the part about the difficulties notes that it holds nuke-scale energies and states "Therefore for safety and astrodynamic reasons, launch loops are intended to be installed over an ocean near the equator, well away from habitation."
That would exclude the downtown-to-downtown feature.
the part about the difficulties notes that it holds nuke-scale energies
Nuke scale energies get dissipated in the atmosphere on a regular basis by thunderstorms. I suspect it may be possible to ensure that most of the mass burns up in the atmosphere and is dispersed.
That would exclude the downtown-to-downtown feature.
A rocketplane could "rendevous" with the electromagnetic loop at high altitude and then be accelerated and decelerated for the bulk of the cross-ocean trip, then land at an airport.
For what it's worth I think the energy related claims are pretty weak. Technically you can store energy in the kinetic energy of the mass moving at speed, and with diamagnetic ('quantum') levitation the losses are very low... however the costs, overall efficiencies, and dynamics make it barely interesting as a theoretical exercise, and totally worthless as a practical one.
Powering with PV on top of the tube, on the other hand, should be entirely realistic (at least on an average consumption vs average generation basis), and the incremental PV cost will be really low since you'd install it as part and parcel of the tube.
At first I thought he meant something similar to Tesla's idea of building a ring around the earth and the blowing away the pillars. Yet I can't seem to find anything about his 'hyperloop' of sorts.
I was wondering the same. For whatever reason, the first thing I thought of when I read that was something like those proposed vacuum tube train things (eg. http://en.wikipedia.org/wiki/Vactrain).
Would it be possible to have a tunnel like that and somehow fill it with air instead, then accelerate the air to something like 2x the speed of sound outside? That was my first association when he said "there are other ways to store energy than batteries". Then you arrange the whole thing in a loop. You could have some sort of carriage that just gets carried along by the airflow.
Anyway - the part about electric VTOL aircraft got me really excited. I've been annoyed that no one has tried to do VTOL aircraft with fans yet. If it could be made electric too (I'm assuming on-board generators or fuel cells here), that would turn a lot of things on its head.
I was thinking along these lines .. but instead of moving the air, remove it from one side of the train, and then allow atmospheric pressure to force it through the tunnel.
Possible, but not efficient. The drag of the air against the interior of the tube will be really high. Much better is to suck all the air out, and use another drive system (maglev with linear motors).
I'm pretty sure it's some variant of maglev in an evacuated tube. Daryl Oster (www.et3.com) has been pushing it for quite a long time. The big difference is that Musk has the contacts and personal background to possibly make it a reality on a reasonable timeframe.
