Creative Speculation

what evidence do you have that the power stations exploded in the basement?

don't forget that Building 7 in fact went down in a conventional manner. it was a classic building implosion.

like Building 7 the two main towers also came straight down more or less into their own footprint, which indicates CD. but they also came down somewhat differently in a way that was never seen before, what you described as an impact point-down collapse. the floors were literally exploded one by one from the top down and why that is would require a proper investigation but I would surmise that it had something to do with the extraordinary height of the Twin Towers...

....which may have been too tall to bring down in a conventional manner (e.g. knocking out the supports and letting gravity do the rest--the classic CD method). they were too tall to bring down conventionally so they did it by literally annihilating each floor one by one. that's what it looked like to me. you can see that in the collapse footage of the Twin Towers that shows each floor exploding and being vaporized to dust one by one from the top down.