January 10, 2021 in Jennifer Sensiba
Zero-emission vehicles are great for the environment, and Tesla manufactures many of them. Elon Musk also owns SpaceX, so people will naturally group them together in their minds. When someone sees a rocket launch, it’s obviously not a zero-emission event. As Jerry Lee Lewis says, “My God, big balls of fire!”
Unfortunately, this leads some to conclude that all emissions from a rocket launch must cancel all saved emissions from a Tesla. I wanted to cover this up for some time and dispel this myth *, but I was hoping for some more solid word on what SpaceX’s plans were for that. With one of Elon Musk’s recent tweets, we now know that zero-emission rockets are definitely coming.
Indirectly, an electric rocket is possible using electricity to convert CO2 + H2O -> CH4 + O2. This will be necessary on Mars even for the first missions and on Earth also over time.
– Elon Musk (@elonmusk) January 7, 2021
First, let’s find out how SpaceX’s emissions are at the moment. Existing and mature SpaceX rocket designs use their Merlin engines. Like many other launch companies and government entities, Merlin engines use RP-1 fuel, which is basically a more refined version of the fuel that most jet engines and oil lamps use (kerosene). They mix it with liquid oxygen and burn it, resulting not only in CO2 and H2O, but also in many pollutants such as hydrocarbons, carbon monoxide and nitrogen oxides.
For newer rockets, like the Starship and the Super Heavy, SpaceX is using its newest Raptor engines. While there are many ways that Raptors 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. When you burn a molecule of methane (CH4) with two molecules of oxygen (O2), you get only carbon dioxide and water in the exhaust, without any of the other contaminants.
That alone is a big advantage of using methane, but, as Elon Musk points out in his tweet, it is possible to make methane rockets even cleaner. The elimination of water vapor does not cause much damage to climate change, but all that carbon dioxide is still a problem.
By capturing carbon dioxide (CO2) from the atmosphere where the rocket left it, you can make up for what the rocket did. You then take the carbon dioxide, add a little water and use the Sabatier Reaction to add the methane again. You can then use methane to power the next rocket.
The result? Zero net emissions.
There is a catch, though: electricity is needed. You need a metal like nickel to act as a catalyst and a lot of electricity to convert carbon dioxide and water into methane. The good news is that it doesn’t matter where the electricity comes from, so you can use solar, hydro, wind or other clean energy. So, if you play it right, you’re still on zero emissions!
It is likely that the first place you will see SpaceX use will be on Mars. On Earth, it is easy to obtain methane from natural gas. After all, it is the main ingredient. Using Sabatier to produce methane is an expensive process compared to buying natural gas, so it still doesn’t make much sense. The current goal is to take the company to Mars and form a colony, which will be an expensive undertaking.
However, there are no natural gas pipelines on Mars. If you want fuel for starships, you’ll need to take a lot of the material to Mars or find a way to get there. It is a long journey to Mars. Even light, the fastest thing we know, takes about 4 to 20 minutes to get there. The long journey and the extra launches would make it prohibitively expensive to bring natural gas there.
On the other hand, the atmosphere of Mars is composed mainly of carbon dioxide and there is a lot of water in the polar caps. It is also possible to use solar panels or other sources of electricity on Mars to power Sabatier’s reaction, so it’s a great way to get fuel for return trips to Earth or even trips elsewhere in the solar system.
The biggest news with Elon Musk’s tweet is that SpaceX eventually plans to produce fuel that way on Earth. We also have a lot of carbon dioxide and water here, but we cannot continue to put more carbon in our atmosphere in the long run. Fortunately, not doing so is part of the future plan.
* Editor’s note: emissions from SpaceX rocket launches are surprisingly low. See these two articles for more information:
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About the author
Jennifer Sensiba Jennifer Sensiba has been an enthusiast, writer and photographer for efficient vehicles for a long time. She grew up around a transmission workshop and has been experiencing vehicle efficiency since she was 16 and was driving a Pontiac Fiero. She enjoys exploring the southwestern United States with her partner, children and animals. Follow her on Twitter to see her latest articles and other random stuff: https://twitter.com/JenniferSensiba Do you think I was helpful in your understanding of Tesla, clean energy, etc.? Feel free to use my Tesla reference code to get (and for me) some small benefits and discounts on your cars and solar products. https://www.tesla.com/referral/jennifer90562