Question

Let's say an average cow emits 100kg of methane per annum.

If coal consists of 80% carbon and 20% moisture and ash, how much coal would I have to burn per annum to have the same global warming potential as one cow.

Assume that the carbon in the coal burns completely.

Answer 1

Global warming potential is the potential of a greenhouse gas to trap heat or absorb heat

For reference CO₂ GWP(global warming potential )= 1

and GWP of other gases is measured with

CO2 as reference

For methane GWP = 86(GWP) _CO2 commonly (approximately)

Cow emits 100 Kg methane /annum

Coal produces CO2 undergoing combustion

To have have same GWP as 100 Kg Methane

Amount of CO2 needed = 86(100) = 8600 Kg

CO₂ needed = 8600 Kg/year

M. W of CO2 = 44 Kg/kmol

Moles of CO2 needed = 8600/44 = 195.454 Kmol

Coal reaction

According to stiochiometry amount of C needed to produce 195.454 kmol CO2 = 195.454(1) = 195.454 Kmol

M. W of C = 12 Kg/kmol

Kg of C needed = 12(195.454) = 2345.448 Kg

Coal contains 80% C

All C is burned

Coal needed = 2345.448/(0.8) = 2931.81 Kg

Coal burned = 2931.81 Kg/annum

Coal burned = 2.931 tons/annum

So 2931.81 Kg of Coal is burned to have same gllbal warming effect as 100 Kg methane

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