Strong scientific evidence that the falling towers lacked the potential energy to pulverize all the concrete AND suspend it in air

The paper is rather scientific, and can be read here: [link to 911research.wtc7.net]

I'll post the conclusion here:

Summary
The dominant energy source assumed to be in play during the leveling of each of the Twin Towers was the gravitational energy due to their elevated mass. The energy sinks included the thorough pulverization of each tower's concrete, the vaporization of water, and the heating of air and suspended concrete dust in the ensuing dust cloud. Estimates for these energies are:

energy, KWH source or sink
+ 111,000 falling of mass (1.97e11 g falling average of 207 m)
- 135,000 crushing of concrete (9e10 g to 60 micron powder)
ignoring water vaporization
- 400,000 heating of gasses (2e9 g air from 300 to 1020 K)
- 11,300,000 heating of suspended concrete (9e10 g from 300 to 1020 K)
assuming water vaporization sink was not supply-limited
- 1,496,000 vaporization of water (2.38e9 g water)
- 41,000 heating of gasses (2e9 g air from 300 to 373 K)
- 1,145,000 heating of suspended concrete (9e10 g from 300 to 373 K)

The imbalance between sources and sinks is striking, no matter the relative shares of the thermodynamic and water vaporization sinks in accounting for the expansion. Moreover, it is very difficult to imagine how the gravitational energy released by falling mass could have contributed much to any of the sinks, since the vast majority of the tower's mass landed outside its footprint. The quantity for the crushing of concrete appears to be conservative since some reports indicate the average particle size was closer to 10 microns than 60 microns. The quantity for the heating of suspended concrete has a large amount of uncertainty, but the energy imbalances remain huge even when it is ignored entirely. All of these energy sink estimates are conservative in several respects.

They are based on an estimate of dust cloud volume at a time long before the cloud stopped growing.
They use a liberal estimate of the contribution of mixing to the volume.
They ignore thermal losses due to radiation.
They ignore the resistance to expansion due to the inertia of the suspended materials, and energy requirements to overcome it.

Conclusion
The amount of energy required to expand the North Tower's dust cloud was many times the entire potential energy of the tower's elevated mass due to gravity. The over 10-fold disparity between the most conservative estimate and the gravitational energy is not easily dismissed as reflecting uncertainties in quantitative assessments.

The official explanation that the Twin Tower collapses were gravity-driven events appears insufficient to account for the documented energy flows.