In 2013 getting your phone charging at 1W at 1m was respectable. Today... no.
iPhone X (and most phones today) use a 10Wh battery, which is good (in my experience) for 7AM->9PM so ... ~14-15 hours.
Average power consumption is therefore ~700mW.
800mW would charge your phone (reeeeeaaaaaalllllllly ssssssssssssssslllllllllllllllllllllllllllllllllooooooooooooooooooooowwwwwwwwwwwwww!).
But if you did have 24/7 wireless power, 1W is all you will need to keep your battery full.
Now, if you have line of sight, range, and orientation issues, you obviously need more. If you can only charge 50% of the time you need 1.5-2W. If you can only charge 10% of the time.... you need 7-10W.
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From the demo they gave at the ourcrowd summit it was clear that
The large unit (the one on the top of their twitter account) has some tracking and phased array capabilities
The small unit (the one they advertise as beta kits), is a good old plane speaker, directing high volume ultrasound forward, no tracking or even detection of receivers.
I think the name "the twitter unit" is suitable for both systems ;-)
https://www.youtube.com/watch?v=azBzKWqUoXU&feature=youtu.be@ 22:50 you can see the beam is fixed, and the detector is inserted into the beam.... if there was tracking (or safety), it would only appear on the center of the plate.
[this is the "beta" unit]
@25:30 you can see how it would look if it was tracking the receiver.
[this is the old unit with the camera- let's call it the twitter demo