Production of cheap CO and CO2 and free H2, CH4, CH2 and carbon.
Production of cheap CO and CO2 and free H2, CH4, CH2 and carbon.
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Direct extraction of CO2 by diffusion from the air into water ponds by Ca(OH)2 solution needs 1144 kwh/ ton CO2 heat for the said solution restoring [1]. Solar thermal can give high temperature heat and wind can do electricity, both of which are about USD 0.004 / kwh or so, by Opex. [2].
a) 0.5 CO2 + 0.5 C = CO – 86.5 kj. If carbon is USD 120/ton, CO = (0.5 * 12 * 120 + 0.5 * 44 * 1144 * 0.004 ) / 28 = < USD 29 /ton CO, consuming heat of (86500 /3.6/28) kwh * 0.004 = USD 3.4 – negligible, and totally about USD 30/ton CO
b) CO + H2O = CO2 + H2, so H2 is free by Opex, if CO2 > USD 19 /ton. Really, H2 = (28 * 30 – 44 * CO2)/2 =< 0, so CO2 = 28 * 30 / 44 = USD 19 or more.
c) CO2 + 4 H2 = CH4 + 2 H2O + 254 kj, and H2 is free here, CH4 = 1144 kwh/ton * USD 0.004/kwh * 44 / 16 = USD 12.6 / ton minus sold electricity from heat of 254 kj/mol at 0.25 energy efficiency and USD 0.05 as local tariff. So CH4 = (254 * 10^6 * 0.25 * 0.05 /(3600 sec * 16) = USD 55/ ton CH4, and totally net profit is 55 -12.6 = USD 42.4 per each CH4 ton produced free [3], as CH2 and carbon produced from CH4 by dehydrogenization are free too.
Here C / CH4 = 2 * 12 /16 = 1.5 ton C/1 ton CH4, and CO2 / CH4 = (4 * 0.5 - 1 - 254/16/64 = 0.75 mol CO2/mol CH4, while
C/CH2 = 1.5 * 12 / 14 = 1.2 ton C / ton CH2 and CO2/CH2 = 0.25 mol /1 mol.
Reference
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