10 January 2021 by Jennifer Sensiba
Zero-emission vehicles are ideal for the environment, and Tesla makes a lot of them. Elon Musk is also the owner of SpaceX, so people are obviously going to pull them together in their minds. Of course, if someone launches a rocket, it’s not a zero-emission event. As Jerry Lee Lewis says, “Goodness gracious, big balls fire!”
Unfortunately, this leads to the conclusion that some people conclude that all the emissions from a rocket should eliminate all the emissions from a Tesla. I wanted to deal with it for a while and dispel the myth *, but waited for a more solid word about what SpaceX’s plans really were for this. With one of Elon Musk’s recent tweets, we now know that rockets without release are definitely coming.
Indirectly, an electric rocket is possible by converting CO2 + H2O -> CH4 + O2. It is needed even on early missions and also on Earth on Mars.
– Elon Musk (@elonmusk) 7 January 2021
Let’s first unpack what SpaceX’s emissions currently look like. Existing and mature SpaceX rocket designs use their Merlin engines. Like many other start-ups and government entities, Merlin engines use RP-1 fuel, which is basically a more refined version of the fuel used by most aircraft engines and oil lamps (kerosene). They mix it with liquid oxygen and burn it, and it gets not only CO2 and H2O, but many pollutants like hydrocarbons, carbon monoxide and nitrogen oxides.
For newer rockets, such as the Starship and Super Heavy, SpaceX uses its newer Raptor engines. Although there are many ways birds of prey are better than Merlins, one of the biggest differences is that they burn methane (CH4) instead of RP-1. Methane can be burned like RP-1, but its molecules are much simpler than kerosene. If you burn a methane molecule (CH4) with two oxygen molecules (O2), you only get carbon dioxide and water in the exhaust gases, with none of the other pollutants.
This alone is a huge benefit to methane use, but as Elon Musk notes in his tweet, it is possible to make methane rockets even cleaner. Emitting water vapor does not cause much damage with climate change, but all the carbon dioxide is still a problem.
By capturing carbon dioxide (CO2) from the atmosphere where the rocket left it, you can compensate for what the rocket did. You then take the carbon dioxide, add water and use the Sabatier reaction to put the methane back together. You can then use the methane to power the next rocket.
The result? Zero net emissions.
However, there is a catch: it requires electricity. You need a metal like nickel to act as a catalyst, and you need a lot of electricity to make the carbon dioxide and water into methane. The good news is that it does not matter where the electricity comes from, so it is possible to use solar power, hydropower, wind power or another clean source. If you play it right, then you have no release yet!
It’s likely that the first place you’re going to see SpaceX will be on Mars. On earth, it is easy to get methane from natural gas. After all, it is the main ingredient. Using Sabatier to produce methane is an expensive process compared to purchasing natural gas, so it does not make much sense yet. The current goal is to get the company to Mars and set up a colony, which is going to be an expensive venture.
However, there are no natural gas pipelines on Mars. If you want fuel for Starships, you have to take a lot of the stuff to Mars or find a way to make it there. It’s a long, long journey to Mars. Even light, the fastest thing we know, takes about 4 to 20 minutes to get there. The long drive and extra launches would make it excessively expensive to get natural gas there.
On the other hand, the atmosphere of Mars is mostly carbon dioxide, and there is a lot of water in the ice sheets. It is also possible to use solar panels or other electricity sources on Mars to drive the Sabatier reaction, so it is a very good way to create fuel for return trips to Earth or even to other places in the solar system.
The biggest news with Elon Musk’s tweet is that SpaceX is finally planning to produce fuel this way. We also have a lot of carbon dioxide and water here, but we can not afford to put more carbon into our atmosphere in the long run. Fortunately, this is not part of the future plan.
* Editor’s note: SpaceX rocket emissions are actually surprisingly low. Read these two articles for more information on this:
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About the author
Jennifer Sensiba Jennifer Sensiba is a tall enthusiastic vehicle, writer and photographer. She grew up in a transmission shop and has been experimenting with vehicle efficiency and driving a Pontiac Fiero since the age of 16. She enjoys exploring the Southwestern United States with her partner, children, and animals. Follow her on Twitter for her latest articles and other random stuff: https://twitter.com/JenniferSensiba Do you think I was helpful with your understanding of Tesla, clean energy, etc? Feel free to use my Tesla reference code to get you (and me) small benefits and discounts on their cars and solar products. https://www.tesla.com/referral/jennifer90562