Calculate Falcon 9 CO2 emissions

Falcon 9 uses Merlin 1 Kerosene based engines. Are there 4 Merlin 1 engines? This seems simple to calculate: Number of Merlin Engines x Merlin 1 fuel capacity(gallons) x Kerosene to CO2 Production.

https://en.wikipedia.org/wiki/Falcon_9

eia.gov says: 19.64 pounds of carbon dioxide (CO2) are produced from burning a gallon of gasoline that does not contain ethanol. About 22.38 pounds of CO2 are produced by burning a gallon of diesel fuel.

• First stage: nine engines(Merlin 1D) burn about 540 gallons of propellant per second Dec 19, 2015 at 7:56
• Burn time v1.1: Stage 1: 180 seconds Stage 2: 375 seconds Dec 19, 2015 at 8:00
• Second stage: 1 Merlin 1D engine modified for vacuum operation Dec 19, 2015 at 8:05
• Are you interested in global warming potential or straight CO2 emissions? Rocket launches influence global warming in more ways than simple CO2 buildup (disruption to the ozone layer, fine particulates etc.) Dec 19, 2015 at 13:19
• A gallon of Kerosene weighs 6.75 LBS and a gallon of LOX at boiling temp/sea level weighs 9.524 LBS. Thus the figure of 22.38lbs/gallon of LOX-RP1 is difficult to understand and likely incorrect. Mar 22, 2017 at 9:20

2 Answers

The mass of the RP-1 fuel of the first stage of Falcon 9 is 119,100 kg. That is around 100,000 kg of carbon, corresponding to 360,000 kg of carbon dioxide. However, according to This pdf, only a little less than half the carbon is completely burnt in hydrocarbon based rocket propellants, the rest becoming carbon monoxide or mono atomic carbon. The figure is then closer to 170,000 kg. The RP-1 fuel of the second stage is 27,850 kg, adding another 40,000 kg of carbon dioxide.

The total is then somewhere around 210,000 kg of carbon dioxide.

The CO will eventually oxidise further to carbon dioxide, so the final amount of CO2 added to the atmosphere is roughly 440,000 kg.

• where did you find RP-1 fuel mass for first and second stage? Dec 19, 2015 at 8:37
• Dec 19, 2015 at 8:43
• @Hohmannfan Interesting reference, though seems heavy going. Does your estimate refer to the prompt production of CO2 or the ultimate end state? I had understood that C0, left in the atmosphere, will collect an extra oxygen atom to become CO2 in time. I will see if I can find a reference. Dec 20, 2015 at 0:01
• Dec 20, 2015 at 14:38

This is what I came up with:

Stage 1:

9 Merlin1D Engines 540gps x 180 secs = 97200 gallons of LOX/RP-1

Stage 2:

1 Merlin1D Engine burns 60 gps 60gps x 375secs = 22500 gallons of LOX/RP-1

119,700 gallons of LOX / RP-1 (Kerosene) 119,700gals x 22.38lbs/gallon = 2,678,900lbs

• I guess this doesn't account for actual burned fuel as @Hohmannfan points out but SpaceX.com states Stage 1 Merlin1D configuration will "burn about 540 gallons of propellant per second" Dec 19, 2015 at 8:36
• The fuel is actually burned, but not completely, instead producing CO. In a LH2/LOX rocket, only about half the hydrogen is burned at all. This is not due to inefficient design, it actually helps to make the performance better. Dec 19, 2015 at 8:49
• I fixed the direct error with your second stage propellant volume missing a zero, thereby derailing your calculation. Be aware that this calculation consider all the 119,700gals to turn into 22.38lbs/gallon, which is the number for burning kerosene, not including oxygen. Dec 19, 2015 at 9:10
• Could you do that in metric units? Dec 19, 2015 at 17:54