Chemical energy of the combustible office contents

The following is a first draft. I have not yet looked up the numbers in the NIST report, I only googled some numbers, and provide ballpark figures for others.

Each of the office buildings was packed with combustibles: paper, wooden furniture, plastics from computers, cables, carpets, etc. Even the bodies of the humans that died in the towers provided combustible material. There were basically two phases when a portion of all these combustibles burned:

1. Open flames in office fire, after plane crash and before building collapse
2. Smoldering underground fires after the collapse

The relevance of the first is to show how much heat was potentially available to heat up and thus damage the steel structure near the impact floors. The relevance of the second is to show why the debris could have burned for so long, created pockets of heat, even melt metals (other than steel, of course), etc. None of this will lead to exact conclusions. My goal is more to give 9/11 truthers a feel for the sheer (potential) magnitude of the fires. Because we again and again find the assertion that fires could not do much damage, and that explosives could do so much more.

First some links:

And some numbers (assumptions), gathered from the links

• Combustibles per quare meter: 20kg/m² (4 pounds per square foot, diveded by (0.3m/ft)², multiplied with 0.45kg/lb. That is a very low value, compared to most office buildings, where a range from 45 to 20 lb/sft is often assumed, due to materials in partition walls and more furniture)
• Office space total in twin towers (both combined): 400,000m²
• Average energy density of office combustibles: 10MJ/kg (this is my own, very conservative, estimate; almost all organic materials rate higher; household waste rates around 8MJ/kg, but it contains a great deal of non-combustibles. The number for paper is about 15, plastics range from 20 to 40)

With these numbers as assumptions, we can derive the following through easy calculation:

• Total mass of combustibles: 8,000,000kg (20kg/m² * 400,000m²)
• Mass of combustibles per floor: 37,000kg (8,000,000kg / 214 office floors; maybe there were some less, or slightly more. I rounded to the nearest 1000)
• Total energy of combustibles: 80,000,000MJ (8,000,000kg * 10MJ/kg)
• Energy per floor: 370,000MJ

The total energy (80,000GW, or 80TW) is roughly that of

• 500,000 gallons of fuel, enough for my car to drive around the earth 700 times
• 20 kilotons of TNT, pretty much equal to the release of the atomic bomb ("Fat Man") that destroyed Nagasaki to end WW2
• the output of a large (1,000MW) block of a modern nuclear reactor in one day

I recall that the debris on Ground Zero burned for 99 day. That's 8.5 million seconds. So the average power was close to 10MW - 1% of a nuclear power plant, or just under the average for a large on-shore wind turbine. Enough to provide a town of 8,000 with electricity for housholds, industry and public infrastructure (in Germany; other countries may use more or less electricity per inhabitant).