Fueling Musk’s Ambitions
- Sean Wessels
- Feb 10
- 5 min read
Building a city on Mars will be a massive infrastructure project here on Earth. It will involve the combined efforts from multiple nations using all our available skill and resources. Using Green hydrogen to support both the Methane and Oxygen production will be a key technology to ensure Elon Musk is provided a reliable fuel for his dream to Mars City.
Elon Musk has his eyes set on building an entirely self-sustaining city on Mars and in contrast to his views on hydrogen for cars, hydrogen and fuel cells will play a huge part in any Mars project, Just as they have done in any space mission since the Gemini programme. It is not a new goal. The conversation started in 2001 at the Mars Society and as early as 2007 he began voicing his personal goal publicly. In 2017 he announced the BFR rocket, which eventually became what we know to be “Starship”. Back then, people laughed. Today, Musk is sitting next to the President of the United States and this ambitious goal has some bite. [1]
“When something is important enough, you do it even if the odds are not in your favor.” Elon Musk
This Martian task, Elon Musk has estimated, will require a minimum mammoth 1 million tons of payload launched from Earth to Mars. That’s an easy 5, packed to capacity, cargo ships.
A simple and practical question to ask is: How do we fuel this mission?
Starship, the largest rocket ever engineered, requires the most amount of propellant of any other rocket in existence. On the launch pad and fully fuelled; Starship with its first stage booster needs approximately 4 600 tons of cryogenic propellant. But that wont get you to Mars. This will only get about 150 tons of cargo and a rocket with zero propellant in the tank in low earth orbit (LEO). To get to Mars, you need to refuel that starship in LEO before it can depart with enough energy. SpaceX designed the Starship system for the purpose of refuelling in orbit and to top-up a departing starship. That means launching additional starships to fill up a depot in orbit, about 150 tons at a time. Under a time crunch. While in LEO, a depot will receive radiation from the sun and earth, warming the cryogenic propellant above its liquid phase causing it to vaporise and dissipate.
In theory, to get a starship with about 100 tons of cargo to Mars, you will need about 52 000 tons of propellant. Comparatively, using our cargo ship analogy again, a very large cargo ship moving about 150 000 to 200 000 tons of cargo needs approximately 75 000 tons of propellant a year. That’s 30% more propellant to deliver ONLY 100 tons to Mars! Both the Starship travelling to Mars and the cargo ship will need an equal amount of time to use the same amount of propellant. In other words, Starship will travel about 1 km per kg of propellant, vs a container ship only traveling 0.0044 km per kg of fuel.
So we will need 52 000 tons of propellant per 100 tons landed on Mars, meaning to build this city, we will need a full 10 000 times this in terms of propellant. A killer 520 000 000 tons of propellant, this is approximately 2,5 times more fuel than the total global annual shipping industry uses in weight. Where are we going to find another entire 2.5 additional shipping industries-worth of fuel, especially in a time when reducing our CO2 emissions is written into our social construct? [2]
The good news is that fueling rockets of Starships’ magnitude does not require the entire coal industry of Africa.
You need two components: a fuel, which is liquid methane (CH₄), and an oxidizer, which is liquid oxygen (LOX). Together, these are referred to as the rocket's propellant. Methane serves as the energy source, while oxygen enables it to combust efficiently within the engine. For Starship, the propellant mix is roughly 1 part methane to 3.6 parts oxygen by mass. This means that what we often refer to as “fuel”, oxygen actually makes up the vast majority of the total propellant weight.
We need about 110 million tons of Methane and 410 million tons of Oxygen. 110 million tons of Methane is an attainable quantity, comprising about 3.8% of current global methane production. If we had to build this city over 20 years, we would have10, 4 - 6 month long launch windows, every 26 months. This means we would need 0.38% of global production of Methane every year.
The carbon neutral method of methane production, while at the same time-consuming large quantities of waste, is through pyrolysis. A process of heating hydrocarbons, like plastics, and plant matter into a high temperature vessel, devoid of oxygen. The output is a variety of compounds such as Methane, carbon monoxide, carbon dioxide, inert biochar and small amounts of other hydrocarbons, often usable in other industries. Some of the Methane can be used to keep the process running as long as you keep feeding it. If you add hydrogen into this process, you massively boost the Methane production while completely reducing the carbon dioxide and carbon monoxide levels. Of course, the additional supply of lots of Green hydrogen will be required, as this will be a critical component in fuelling Starship.
Oxygen is the largest component of rocket propellant. Fortunately, oxygen is relatively easy to extract. There are a number of ways to produce pure oxygen, but one of the cheapest comes from capturing the waste oxygen from Green hydrogen production.When green hydrogen is made, water electrolysis splits hydrogen from oxygen molecules. The Hydrogen is used and shipped to where in needs to go, possibly to help create more methane. But the oxygen is generally discarded, it’s a waste gas and has very little value. And for every kilogram of hydrogen is produced, about 8kg of Oxygen is produced.
There are a few regions that have funding and approval for Green hydrogen projects. Some of them, such as the proposed 60 GW hydrogen production facility in Mozambique by Jearrard Energy Resources Ltd will produce about 170 000 tons of oxygen per day, as a waste gas. If captured and piped to one of NEXUS SPACE PORT nearby launch sites, you would have enough near free oxygen for 3 Starships to launch to Mars daily.
Building a city on Mars will be a massive infrastructure project here on Earth. It will involve the combined efforts from multiple nations using all our available skill and resources. Using Green hydrogen to support both the Methane and Oxygen production will be a key technology to ensure Elon Musk is provided a reliable fuel for his dream to Mars City.
References:
Comments