I think you're off by a factor of 1000. I get 980 terawatt-hours of energy. If, as you say, 971 GWh is equivalent to 6% of total energy usage, then 980 TWh is

I think you're off by a factor of 1000. I get 980 terawatt-hours of energy. If, as you say, 971 GWh is equivalent to 6% of total energy usage, then 980 TWh is 6000% total energy usage. Of course, you don't get 100% efficiency in incineration, but an oversupply of 60x leaves a lot of room for inefficiency. Here's my calculation. I've used scientific notation to reduce the possibility of order-of-magnitude errors: > 230 million tons Avoirdupois = 2.3e8 tons > 2.3e8 tons * 2e3 pounds/ton = 4.6e11 pounds > 4.6e11 pounds * 0.45 kg/pound = 2.07e11 kg > 2.07e11 kg * 1000 g/kg = 2.07e14 g > 2.07e14 g * 17 kJ/g for carbohydrates = 3.52e15 kJ > 3.52e15 kJ * 2.78e-4 kWh/kJ = 9.8e11 kWh That's 980 billion kWh, or 980 million MWh, or 980 thousand GWh, or 980 TWh. I wonder if maybe you're getting nutrition Calories (uppercase) confused with gram calories (lowercase). Nutrition Calories are actually kilocalories!!! If you forgot to multiply by 1000 to account for this, then that would explain your result. In Europe, nutrition labels are listed in kilojoules. This eliminates the confusion over calories.