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Monday, April 25, 2022

Fossil energy cost analysis puzzles

 Santos proposes making hydrogen for $2 per kilogram from methane. 

With 48 kgs of methane Santos might make 84 kgs of carbon monoxide and 12 kgs of hydrogen. 

methane + oxygen → hydrogen+ carbon monoxide

3CH4(g) + 3/2O2(g)6H2(g) + 3CO(g)

 

The 84 kgs of carbon monoxide then could be used in two different processes: 

Reaction with 54 kgs of steam to produce another 6 kgs of hydrogen and 132 kgs of carbon dioxide, 

steam + carbon monoxide → hydrogen+ carbon dioxide

3H2O(g) + 3CO(g) → 3H2(g) + 3CO2(g)

or 

Reaction with 160 kgs of iron ore to produce 112 kgs of iron and 132 kgs of carbon dioxide.

iron(III) oxide + carbon monoxide → iron + carbon dioxide

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

With the first option, the 6 kgs of hydrogen produced at a value of $2 per kilogram would be worth $12. 

With the second option, the 160 kgs of iron ore would cost about $16 (at $100 per tonne for iron ore) and the 112 kgs of iron produced, at a value of $3 per kilogram would be worth $336. 

See Redox reactions are involved in the extraction of metals from their ores

Blast furnace reducing iron ore to iron

 

QUESTION/PUZZLE

Why would Santos propose making hydrogen worth $12 from carbon monoxide made from methane when it could produce iron worth $336 from the same amount of carbon monoxide?