Task 4 (Extension).
You have been provided with a variety of data, including chemical formula, balanced equations, heats of combustion/heat values, and densities for common fuels. Likewise, the efficiencies of typical power plants for each type of fuel are also provided. Based on this information create your own model in Excel for calculating a carbon footprint.
a)First you will need to determine a formula for each variable. For instance, wood is composed of carbon, hydrogen and oxygen, primarily polymers of sugar (C6H12O6). When burned C6H12O6 + 6 O2 6CO2 + 6H2O. With a molecular weight of 180g/mole, or just over 5 moles per Kg, and considering a cord of wood is approximately 1500 to 2000kg,
1 cord x 1750 kg x 5.6 mole sugar x 6 moles CO2 x 0.044kg = 2587 kg CO2
1 cord 1 kg sugar 1 mole sugar 1 mole CO2 1 cord
Also, the wood produces 15MJ/kg so 1750 kg x 15MJ/kg x 1000 KJ/MJ = 2.625 x 107KJ
So, my Spreadsheet would have column A (cords of wood burned) and B (CO2 from wood). In B, the formula B3=A3*2587 would convert whatever cords were put in A2 into kg of CO2 in B3.
ABCDE …Z (total CO2)
1 cordsCO2
2 3 =A2*2587= B2+D2+...
3
b)if no formula is available, then try to look for an appropriate approximation. For instance, in the above example, if the best information you can find is that 10,000,000 cords of wood was burned last year/300,000,000 people in the USA, gives an average of 86 kg of CO2 per person in the U.S. from firewood. You could do these averages on a statewide or countrywide basis.
Carbon Foot-Print equations
Burning a gallon of gasoline:
2C8H18 + 25O2 16CO2 +18H20
From one gallon of gasoline, 8.21 kg of CO2 is produced:
0.003785 m3 / 702.5 kg of C8H18 / 1 mol C8H18 / 16 mols CO2 / 0.044 kg CO2 / 8.21 kg1 gallon / 1 m3 / 0.114 kg C8H18 / 2 mole C8H18 / 1 mol CO2 / CO2
One gallon of gasoline releases 1.25 x 105 kJ of energy when it is combusted:
0.003785 m3 x / 702.5 kg of C8H18 x / 47 MJ x / 1000 kJ = / 1.25 x 105 kJ1 gallon / 1 m3 / 1 kg C8H18 / 1 MJ
Burning a gallon of diesel
4C12H23* + 71O2 46CO2 + 48H2O
In one gallon of diesel, 9.75 kg of CO2 is produced:
3.785 L / 0.85 kg of C12H23* / 1 mol C12H23* / 46 mols CO2 / 0.044 kg CO2 / 9.75 kg1 gallon / 1 L / 0.167 kg C12H23* / 4 mol C12H23* / 1 mol CO2 / CO2
*Most common diesel fuel formula according to Wikipedia.org
One gallon of diesel releases 1.42 x 105 kJ of energy when it is combusted:
3.785 L x / 0.83 kg of C8H18 x / 45 MJ x / 1000 kJ = / 1.42 x 105 kJ1 gallon / 1 L / 1 kg C8H18 / 1 MJ
Burning a gallon of propane
C3H8 + 5O2 3CO2 + 4H2O
In one gallon of propane,5.79 kg of CO2 is produced:
0.003785 m3 / 510.0 kg of C3H8 / 1 mol C8H18 / 3 mols CO2 / 0.044 kg CO2 / 5.79 kg1 gallon / 1 m3 / 0.044 kg C3H8 / 1 mol C3H8 / 1 mol CO2 / CO2
One gallon of propane releases 9.63 x 104 kJ of energy when it is combusted:
0.003785 m3 x / 510.0 kg of C8H18 x / 49.9 MJ x / 1000 kJ = / 9.63 x 104 kJ1 gallon / 1 m3 / 1 kg C8H18 / 1 MJ
Burning a gallon of fuel oil
C13H28 + 20O2 13CO2 + 14H2O
In one gallon of fuel oil, 8.895 kg of CO2 isproduced:
3.785 L / 0.756 kg C13H28 / 1 mol C13H28 / 13 mols CO2 / 0.044 kg CO2 / 8.895 kg CO21 gallon / 1 L / 0.184 kg C13H28 / 1 mol C13H28 / 1 mol CO2
One gallon of fuel oil releases 1.26 x 105 kJ of energy when it is combusted:
3.785 L x / 0.756 kg of C13H28 x / 44 MJ x / 1000 kJ = / 1.26 x 105 kJ1 gallon / 1 L / 1 kg C13H28 / 1 MJ
Burning a gallon of natural gas (Methane)
CH4 + 2O2 CO2 + 2H2O
In one therm of natural gas, 3.14 kg of CO2 is produced:
1 Therm / 1gallon / 0.003785 m3 / 422.4 kg of CH4 / 1 mole CH4 / 1 mol CO2 / 0.044 kg CO2 / 3.14 kg1.4 Therm* / 1 gallon / 1 m3 / .016 kg of CH4 / 1 mol CH4 / 1 mol CO2 / CO2
* According to the website.
One therm of natural gas releases 5.71 x104 kJ of energy when it is combusted:
1 Therm / 1gallon / 0.003785 m3 / 422.4 kg of CH4 / 50.009 MJ / 1000 kJ / 5.71 x104 kJ1.4 Therm* / 1 gallon / 1 m3 / 1 kg CH4 / 1 MJ
Burning a gallon of ethanol
3.785 L / 0.789 kg C2H6O / 1 mol C2H6O / 2 mols CO2 / 0.044 kg CO2 / 5.713 kg1 gallon / 1 L / 0.046 kg C2H6O / 1 mol C2H6O / 1 mol CO2 / CO2
3.785 L x / 0.789 kg of C2H6O x / 29.8 MJ x / 1000 kJ = / 8.9 x 104 kJ
1 gallon / 1 L / 1 kg C2H6O / 1 MJ
Burning a kg of coal
1 kg = 1.5 x 104 – 2.7 x 104 kJ (depending on quality, lignite (ND coal) on the low end, anthracite on the high end).
1kg of coal releases 3.4 kg of CO2.
Burning a kg of hydrogen gas gives off 1.419 x 106 kJ of energy and no CO2, but you have to make it… And a kg of hydrogen would fill about 1 million 2 liter bottles…
Wind, nuclear, solar, most geothermal, hydroelectric, hydrogen, produce no CO2 pollution.
How much CO2 is produced in mining, refining, shipping, growing the fuel?
Is it fair to count the CO2 that the corn takes out of the air as it grows as a benefit? What would grow in the field if you didn’t grow corn for fuel, or do you think it would be a bare dirt field? What would eventually happen to the plant matter that grew?
A steam power plant, whether the heat comes from coal, nuclear, etc. is about 33% efficient.
With a gas turbine and co-generator, natural gas can be 45% efficient.
A couple more links to think about for this week.
Finally. Go back to
Compare the nations with the most CO2 per capita to the various forms of getting electricity.
here is an example graphing CO2 per capita and coal per capita…