I can't leave this alone

Ok, just two points.

1) Of course using foam cups incurs variable energy costs. Every time you throw one away, it has to be carried to the dump. I don't know anything about MJs. And maybe the energy cost of taking one foam cup on a garbage truck is so tiny that it doesn't matter. But look what happens when you assume that the energy cost is 1/10,000th of an MJ.



See the way that line starts to grow? At 1,500 uses, you're almost at twice the Average Total Cost than one use. That's the power of big numbers.

2) You could cut the energy use in the foam option significantly by simply reusing foam cups. If you use the same cup twice before throwing it out, you cut the already low energy use in half, making it a much more attractive option.