ElMondoHummus
0.25 short of being half-witted
Ahh what the heck - here is my calculation - rough draft:
- Combustibles per quare meter: 100kg/m2 (that is a very low value, compared to most office buildings)
- Office space area: 400,000m2-> Total mass of combustibles: 40,000,000kg
- Average energy density of office combustibles: 10MJ/kg (again, that is a very low estimate; paper has more, plastics have much more)
-> Total energy of combustibles: 400,000,000MJ.
- This is the energy found in roughly 2.5 million gallons of fuel, or 100,000 tons of TNT
- Seconds in 99 days are 99*24*60*60 = 8,553,600s
-> Power of fires in 99 days: 47MW
47MW is the average net electrical power consumption of a city of more than 40,000 people in Germany (including housholds, industry and public sector).
My car has a power output of 90kW or 0.09MW. So the fires had the power of 500 times my car.
One block of an average nuclear power plant has an output of 1000MW, or 21 times the power of that debris fire.
The largest onshore wind turbines have a power of 1.5 MW. You need about 30 of these to equal the power of GZ.
Conclusion: There was plenty of combustible energy to be released by fires for 99 days.
FYI, the University of California Davis "Delta" group did their own calculation. You can find it here:
Very Fine Aerosols from the World Trade Center Collapse Piles: Anaerobic Incineration?
... and they're thinking this:
So, 85% of that last line's figure would be 36,550,000 megajoules. You and they disagree by an order of magnitude.
Despite the difference, I don't see anything unreasonable in your back-of-the-envelope calculation at all; I'd guess they simply dug a bit deeper for their numbers. I wouldn't even call yours wrong, necessarily, since the Delta group doesn't elaborate on what specifically they added up to get their figure. Still, though, regardless of whether it's 36MJ or 400MJ, the fact remains that there was plenty of combustibles present to account for the length of time the rubble pile burned. Even the lower figure is still plenty.
Anyway... thought you may be interested in other calculations. BTW, if you aren't able to download that presentation, I do have it on PowerPoint and can send it to you. Just PM me, and I'll take care of it later.