January 10, 2021 by Jennifer Sensiba
Zero-emission vehicles are great for the environment, and Tesla makes a lot of them. Elon Musk also owns SpaceX, so people will naturally cluster them in their minds. When someone sees a rocket launch, it’s obviously not a zero emission event. As Jerry Lee Lewis says, “Gracious goodness, great balls of fire!” ”
Unfortunately, this leads some people to conclude that all emissions from a rocket launch must cancel all emissions saved from a Tesla. I’ve wanted to cover this for a while and dispel this myth *, but I was waiting for a more solid word on SpaceX’s plans in this regard. With one of Elon Musk’s recent tweets, we now know that zero-emission rockets are sure to come.
Indirectly, an electric rocket is possible by using electricity to convert CO2 + H2O -> CH4 + O2. This will be necessary on Mars even for the first missions and Earth as well over time.
– Elon Musk (@elonmusk) January 7, 2021
First, let’s take a look at what SpaceX shows look like right now. Both 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 essentially 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, and it comes out not only CO2 and H2O, but also a lot of pollutants like hydrocarbons, carbon monoxide and nitrogen oxides.
For new rockets, like the Starship and the Super Heavy, SpaceX uses its new Raptor engines. While Raptors are better than Merlins in many ways, 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 one molecule of methane (CH4) with two molecules of oxygen (O2), you only get carbon dioxide and water in the exhaust, without any of the other contaminants.
That alone is a big plus to using methane, but as Elon Musk points out in his tweet, it is possible to make methane rockets even cleaner. Turning off water vapor doesn’t cause much harm with 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 compensate for what the rocket did. You then take the carbon dioxide, add water, and use the Sabatier reaction to reconstitute the methane. You can then use the methane to fuel the next rocket.
The result? Zero net emissions.
There is a catch, however: it requires electricity. You need a metal like nickel to act as a catalyst, and you need a lot of electricity to turn carbon dioxide and water into methane. The good news is that no matter where the electricity comes from, it is therefore possible to use solar power, hydropower, wind power or some other clean source. So if you play it right you are still zero emissions!
It’s likely that the first place you’ll see SpaceX using it will be on Mars. On Earth, it’s easy to get methane from natural gas. After all, it is the main ingredient. Using Sabatier to make methane is an expensive process compared to buying natural gas, so it doesn’t make much sense yet. The current goal is to bring the company to Mars and create a colony, which will be an expensive endeavor.
However, there is no gas pipeline on Mars. If you want fuel for the spaceships, you’ll either have to take a lot of stuff to Mars or find a way to get there. It’s a long, long journey to Mars. Even light, the fastest thing we know, takes between 4-20 minutes to get there. The long trip and the extra launches would make natural gas prohibitive.
On the other hand, the atmosphere of Mars is mostly carbon dioxide and there is a lot of water in the polar ice caps. It is also possible to use solar panels or other sources of electricity on Mars to power the Sabatier reaction, so this is a very good way to find fuel for trips back to Earth or even trips. to other places in the solar system.
The biggest news with Elon Musk’s tweet is that SpaceX ultimately plans to produce fuel this way on Earth. We also have a lot of carbon dioxide and water here, but we can’t afford to keep putting more carbon into our atmosphere in the long run. Fortunately, not doing this is part of the future plan.
* Editor’s Note: SpaceX rocket launch emissions are actually surprisingly low. Check out these two articles to learn more:
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Sell Teslas in 2012 compared to 2021