He's buying them from Mr West; that's probably why he's been so delayed recently.

Typical commercial power supplies are something like ~6W-10W/cubic inch.

They don't specify dimensions, but if we assume 4" by 1" cylinder with 100% available for the power electronics (unrealistic, given the need for the large graphene capacitor, connectors and casing materials) then that gives them ~3.1 cubic inches available.

Enough for an optimistic 30 watts, or more realistically something like 10~15 watts. Comparing the assumption to something like an iPad charger, which delivers 11 watts, and is about the same volume, this seems like a present limit.

To reach an optimistic 108 watts, they'd need about 12in^3, or in a similar form factor, make the device diameter twice as large, or length four times as long. This also assumes the graphene capacitor as being negligible in size.

Maybe they can get more peak power out of the device, but continuous power is less ... still, for power transistors, 5 minutes may as well be DC...