Scale of the problem -- Nature Preserve Earth

In the original calculations I left out the cost of turning atmospheric CO2 into carbon nanotubes for EdenCrete because my intuition was that I could neglect it to first order. That intuition is borne out by the following:

Production of carbon nanotubes from CO2 and H2O with AVE electricity for structural material (EdenCrete) might involve electrolytic H2 for the Sabatier reaction to produce methane, which is the feedstock for producing carbon nanotubes used by EdenCrete.

The cost of extracting carbon in the form of CO2 from the atmosphere with electricity:

1200kWh/(ton co2);12ton carbon/(44ton co2)?MJ/(kg carbon)
= 17.4606 MJ/(kg carbon)

The electrical energy to convert H2O+CO2 to methane thence to carbon via the Sabatier reaction is the cost of converting H2O to H2 for that reaction via CH4 minus its 4 hydrogens:

42kWh/(kg hydrogen);8kg hydrogen/(16kg carbon-4kg carbon)?MJ/(kg carbon)
= 100.8 MJ/(kg carbon)

For a total electrical energy cost of carbon nanotube mass of:

17.4606 MJ/(kg carbon)+ 100.8 MJ/(kg carbon)?MJ/(kg carbon)
= 118.261 MJ/(kg carbon)

So the EdenCrete electrical cost of carbon nanotubes, at 100oz/yd^3 (the high end requirement to be conservative):

118MJ/(kg carbon);100oz carbon/(yd^3 EdenCrete);2.7tonne EdenCrete/(m^3 EdenCrete)?MJ/(tonne EdenCrete)
= 162.052 MJ/(tonne EdenCrete)

The Calera process requires 3.3GJ of electricity to produce one tonne of concrete as input to the production of EdenCrete, so the total energy cost remains essentially unchanged at 3.5GJ electricity to produce one tonne of EdenCrete – which is what I intuited hence did not include in the original post back in 2014.

The electrolytic hydrogen system for the above calculation:

This is yet another of the companies out of Australia – Australia that I predicted could play a leading role along with the “strange bedfellow” CCP in transferring technological civilization to these artificial atolls.