Mass production of CO2 at attractive cost from the air

CO2 production in huge amount at attractive cost from air

Author: David Judbarovski, systems engineering, principle inventor

judbarovski@gmail.com

Introduction  

Being twice/triple more energy effective, and much more convenient and save in usage vs. fuels, electricity can be practically only energy source for human live and global economics, if being cheap and inexhaustible and made from renewable primary energy and by recyclable cheap materials and tools for them.

Carbon dioxide is one of the said materials, and can be produced from atmospheric air, then to produce carbon based chemicals to store such energy in compact and easy transportable form, and for other applications.

It can save our planet against global warming.

Here I will show a method of such CO2 production at attractive cost by cheap energy

Note: Referring to my archive of some decades of work, being constantly upgraded and updated, I can declare that solar and wind energy can be cheaper USD 0.01/kWh (as heat as electricity), even several times cheaper, even if at engineering level of past ages.

Abstract

Ca(OH)2 solution produced from CaO and water in separate small tanks, gradually intakes in corresponding ponds opened to the air, and capturing its diffused carbon dioxide by the said Ca(OH)2 in form of CaCO3 sediment, gradually extracted from the said pond and thermally decomposed in CaO  recycled and in CO2 as a product by about USD 15.0/ton or cheaper, in quantity about 320 ton annually per each m2 of the ponds’ area.

Detailed disclosure for experts:

(1) CaO (s) + H2O (l) = Ca(OH)2 (aq)  (diluted aqueous solution at separate tank, up to 1.6 kg/m3, if at 25 C)

(1a) Ca(OH)2 (aq) = Ca(2+) + 2 (OH) (-)

(2) Ca(OH)2 (aq) + CO2 (aq) = H2O + CaCO3 (sediment on the pond bottom).

CO2 concentration is constant of 0.6 gram/m3 at the solution surface and diffused through the water at D (diffusion coefficient) = 0.185 m2/s)

More detailed it is:

(a) CO2(g) = CO2 (aq)

(b) CO2 (aq) + H2O = H2CO3(aq)

(c) H2CO3 (aq) = H (+) + HCO3 (-)

(d) HCO3 (-) = H(+) + CO3 (2-)

(e) Ca (2+) + CO3(2-) = CaCO3

The system productivity is determined by Ca(OH)2 intake in the pond =  Q2(g/s),

and by CO2(aq) diffusion through the pond being

Q1(g/s) = 0.185 m2/s * (0.6 g/m3 /H m) * S m2 = (0.11 / H) * S

Here H (m) is depth below which CO2 is completely captured, and S (m2) is its surface area.

Q2 (g/s) fully react with Q1 = (M=44/M=74) * Q2 = (0.11/ H) * S, so

Q2 = 0.11 * 74/44 * V / (H^2) = 0.187 * V / H^2, or

Q2 / V = 0.187 / H^2.

Here V (m3) = S * H

Q2 / V = Ca(OH)2 intake to the pond (g/s) per m3 of V, and can be less or equal to saturated concentration of Ca(OH)2 can be unchanging. Let it be equal 1600 g/m3/s, saturated.

So H^2 = (0.187/1600), so H = 0.01075 m.

The pond depth must be bigger than 2 * H, e.g. to be 1 m or less.  

Q1 = 0.11 / H = 10.2 g/s / m2.  CO2 is diffused from the air to the pond almost instantly, because diffusivity of CO2 in air is great D = 16.0 mm2/s, and practically instantly captured in thin layer by much more concentrated Ca(OH)2 especially, if pH >=10.0)

Now we are ready to evaluate CO2 production:

Q1 = 10.0 g/s CO2/m2 of the pond, or 320 ton/m2/year. It is tremendously bigger, than any other rational alternatives from atmospheric air, and total worldwide 100.0 km2 ponds would be enough to provide the artificial oil production in quantity of all mankind demand.

Further we must extract the said carbon dioxide by thermal decomposition CaCO3 sediment in quantity 1.0 mol. CO2 per 1.0 mol. CaCO3, and energy for it being 180.0 kJ/mol., is a lion share of expenditures, while the others are relatively negligible.  

Really,

CaCO3 = CaO + CO2 – 1207 kJ + 635 + 393 = - 180 kJ

1.0 mol. CO2 needs 180 kJ/3600 sec = 0.05 kWh, or 1140.0 kWh/ton CO2, so in a force of my Note above, it is less than USD 12.0/ton + 20% for others ~= USD 15.0/ton CO2

References:

[1] “Carbon Dioxide Capture Using Calcium Hydroxide as the Absorbent”, Energy and Fuels, 25(8) July 2011, 3825-3824. DOI: 10.1021/e/200415p , PhD Sang-Jun Han, Catholic University of Korea, et al

[2] “Kinetics of the CaO / Ca(OH)2 Hydration/Dehydration Reaction for thermochemical Energy Storage Applications”, Ind. Eng. Chem. Res., 2014, 53, 32, 12594-12601, Yolanda A. Criado, Instituto National del Carbon, at al., https://pubs.acs.org/doi/10.1021/ie404246p

[3] “Kinetics of the Reaction of Ca(OH}2 with CO2 at low temperature”, Eng. Chem.Res., 1999, 38 (4) 1316-1322,  https://doi.org/10.1021/ie980508z, Shin-Min Shin, et al

[4] “Mass Diffusivity”, Wikipedia