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One of the possible ways trying to solve the present global temperature rising problem would be, as proposed by the Musk Foundation XPrize, a CO2 removal at an increasing rate up to attain one Gigaton/year scale by 2050, and to achieve this, to stock wood for at least hundred years into closed green concrete silos (Fig.1), seems to be a simpler, cheaper, and more reliable solution than many other currently being considered.

A 15% humid Eucalyptus and Pinus wood contains about 37% of cellulose (C6H205), 21% of linin (C9H10)3), and 27% of hemicell (C5H2O4), and so from the equation:
it can be shown by stoichiometry (Fig.2), that to stock one Ton of them, is to stock 150 kg of water together with 850 kg of the wood solid material that was formed by the sun driven photosynthesis reaction of additional 482 kg of water with 1.500 kg (764 m3) of CO2 removed from the atmosphere, with the release back to it of 1,132 kg (792 m3) of oxygen.

To plant in savannah soils rapid growing trees such as Eucalyptus or Pinus, following the procedures used by wood paper and pellets industries. To cut the trees in a rotating scheme, leaving branches and leaves for soil fertilization, and let their trunks dry in open air up to attain natural equilibrium humidity level (~15%). To slice, and store the trunks in the green (for CO2 compensation) concrete prefabricated closed silos.

Numerical Example:
Considering a typically 7 years grown eucalyptus the production of 1000 T CO2/year will require about 20 hectares of savannah land being cut each 7th year.

Saw logs slices could then be stored into 300 m3 green concrete pre-fabricated silos, installed in each forested area center to minimize transport costs.
All necessary equipment for soil management, tree planting, cutting and transportation, shall be electric driven, with solar panels used for their battery charging.

The 1 Gigaton/year CO2 removal scale could then be attained in 2050 (Fig 3) by stocking the wood obtained from the forestation of ~419.430 km2 of savannah land (a fraction of the ~30.000.000 km2 of estimated earth savannah land, (~267.000 km2 of it within amazon territory!) if done at an increasing 100%/year rate from the 20 hectare start.

Rough cost estimate for 1 Megaton/year CO2 removal:
Not taking into account the cost reductions that could be obtained from carbon credits, and by selling part of the wood for uses where it could be demonstrated that it will not deteriorate though a 100 years lifespan (biochar, wood buildings, etc.) we have:

Assuming for Eucalyptus: density ~0.7 Ton/m3, price ~15 US$/m3, and a silo initial cost of ~35.000 US$ with a fabrication learning cost reduction function: Cn = C1.n-0.322 / (1-0.322), with C1=first unity cost, and n=number of unities built, we have: the cost of 3275 silos 22,7 million US$, and a maximum cost for the 982547 m3 of stocked eucalyptus wood 14,7 million US$, a total cost estimate of 37,4 million US$.


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  • Name:
    Francisco Leme Galvao
  • Type of entry:
    Team members:
    • Roberto Stickel
  • Software used for this entry:
    Microsoft Office: Word and Excell and Photosuite SE.
  • Patent status: