Question

Using the data on gross (higher) heating values (HHV), estimate the mass of CO2 emitted per: 1) 1000 SCF of methane; 2) lb of gasoline; 3) ethanol; and, 4) No. 2 heating oil. Also express your answers in mass of CO2 per million Btu of each fuel.

Answer 1

1 ) CH4 + 2O2 -------------------> CO2 + 2H2O

      16g                                         44g

1g = 3.5 x 10^-5 SCF

16 g CH4 = 16 x 3.5 x 10^-5 SCF = 5.6 x 10^-4 SCF

44 g CO2 = 44 x 3.5 x 10^-5 SCF = 1.54 x 10^-3 SCF

5.6 x 10^-4 SCF   CH4 gives -------------------------> 1.54 x 10^-3 SCF CO2

1000 SCF CH4 gives -----------------------> x SCF CO2

x = 1.54 x 10^-3 x 1000 / 5.6 x 10^-4

CO2 = 2750 SCF mass

1 SCF = 1000 Btu

2750 SCF mass = 2750 x 1000 = 2750000 = 2.75 million Btu

CO2 mass = 2.75 million Btu

2)

Gasoline can be represented by octane C8H18. Its combustion, in the most straight-forward sense is to carbon dioxide and water.

2C8H18 + 25O2 --------------------> 16CO2 + 18H2O

228 g                                               704g

1 lb = 453.59 g                               1.55lb

228 g = 0.5026 lb

0.5026 lb gasoline gives -----------------------> 1.55 lb CO2

1 lb gasoline gives ---------------> 1.55 / 0.5026 = 3.1 lb CO2

3.1 lb = 3.1 x 453.59 = 1406 g

1g = 3.5 x 10^-5 SCF

1406 g = 1406 x 3.5 x 10^-5 SCF = 0.049 SCF = 49 Btu = 4.9 x 10^-5 million Btu

note : regarding C and D problems :ethanol mass is not given . and i do not understand what is 2 heating oil