4x10^11 joules = 400000000000 J
1.0 British thermal unit (Btu) = 1055 joules (1.055 kJ)
=> 400000000000 J / 1055 J = 379146919.43127962085308056872038 Btu
1.0 kilowatt-hour (kWh) = 3413 Btu
=> 379146919.43127962085308056872038 Btu / 3413 Btu = 111089.04759193660148053928178154 kWh
Okay, fun equations aside now (what can I say, I like double-checking math)
Quote:
...Robert Fowler, senior engineer at the structural engineering firm of McNamara and Salvia...
"Though the WTC towers stood over 1,360 feet above the street level, the structures' bases were actually set 70 feet into the ground, and one had a 100-foot-tall antenna atop it, so with 205-foot widths, they had a lot of [exterior] area facing the wind," the engineer stated. He calculated that the approximate maximum wind shear force that a single face needed to withstand to be somewhere around 11,000,000 pounds. The gravity loads (weight) produced by the towers at their bases were on the order of 500,000 tons, Fowler said.
...
Kausel also reported that he had made estimates of the amount of energy generated during the collapse of each tower. "The gravitational energy of a building is like water backed up behind a dam," he explained. When released, the accumulated potential energy is converted to kinetic energy. With a mass of about 500,000 tons (5 x 108 kilograms), a height of about 1,350 ft. (411 meters), and the acceleration of gravity at 9.8 meters per second 2, he came up with a potential energy total of 1019 ergs (1012 Joules or 278 Megawatt-hours). "That's about 1 percent of the energy released by a small atomic bomb," he noted.
The M.I.T. professor added that about 30 percent of the collapse energy was expended rupturing the materials of the building, while the rest was converted into the kinetic energy of the falling mass. The huge gray dust clouds that covered lower Manhattan after the collapse were probably formed when the concrete floors were pulverized in the fall and then jetted into the surrounding neighborhood. "Of the kinetic energy impacting the ground, only 0.1 percent was converted to seismic energy," he stated. "Each event created a (modest-sized) magnitude 2 earthquake, as monitored at Columbia University's Lamont-Doherty Observatory, which is located about 30 kilometers away from New York City." Kausel concluded that the "the largest share of the kinetic energy was converted to heat, material rupture and deformation of the ground below."
from
http://www.public-action.com/911/jmcm/sciam/
What this would imply is
10^12 joules = 1000000000000 J
1.0 British thermal unit (Btu) = 1055 joules (1.055 kJ)
=> 1000000000000 J / 1055 J = 947867298.57819905213270142180095 Btu
1.0 kilowatt-hour (kWh) = 3413 Btu
=> 947867298.57819905213270142180095 Btu / 3413 Btu =
277722.61897984150370134820445384 kWh which is greater than Jim Hoffman's estimated 135,000 kWh needed to pulverize the concrete.
Okay, so why the big difference from the FEMA estimated 4 x 10^11 joules and Kausel's 10^12 J?
My guess, the FEMA estimate deals with the potential energy stored during construction of the towers and does not necessarily include all the stuff inside the towers. Whereas, Kausel is using Fowler's estimate of 500,000 tons of gravity load produced by the towers.
ETA: Site I used for the conversion formulas
http://bioenergy.ornl.gov/papers/misc/energy_conv.html
ETA^2: Formatting
If this conversation ever progresses to some actual evidence, or that "science and math" that TruthSeeker feigned interest in, I'll toddle on back. Until then, no need for me to add anything.
