It really doesn't require math as sophisticated as the napkin kind. Thermodynamics tell the whole story and it's so unfavorable that the actual range of achiev

It really doesn't require math as sophisticated as the napkin kind. Thermodynamics tell the whole story and it's so unfavorable that the actual range of achievable costs for energy input to DAC can vary wildly, and in relation to the prevailing market value of energy in general which is subject to major variation itself. And still none of the actual dollar amounts really matter and can be effectively canceled so the moving target component can be conveniently overlooked numerically. It simply requires the cost of the energy input to be a small fraction of the actual market value of that energy. Whether or not fossil fuels are the primary factor which sets the market value at the time. DAC only really works with remarkable effectiveness when the cost of the energy input approaches zero relative to its market value. And once you've got that low cost supply of energy, then the "sustainability" of the process depends on your continued inability to directly sell your unmatched low-cost energy wholesale, and your commitment to forego dramatic multiples which dwarf the expectations of most shareholders of the oil companies themselves.