A long time ago, human beings began to look up at the stars. With the development of science and technology, human beings have rushed out of the blue planet where they survived and began to explore the vast universe. In order to go further in the universe, rocket fuel is naturally important.
A US start-up, Green Hydrogen International (GHI), recently announced a 60GW renewable hydrogen project in Texas that will be powered by wind and solar energy and stored in salt caverns.
▲Salt cave storage, picture from: Green Hydrogen International
This "Hydrogen City" in Duval, South Texas, will be the world's largest green hydrogen production and storage center. After completion, it will produce more than 2.5 million tons of green hydrogen (hydrogen produced from renewable energy sources such as photovoltaic power generation, wind power and solar energy) per year. ), which is equivalent to about 3.5% of today’s global production of grey hydrogen (the hydrogen produced by burning fossil fuels).
The project is centered on the hydrogen storage facility at Piedras Pintas salt dome in Duval, which will pipe green hydrogen to Corpus Christi and Brownsville, where it will be converted into green ammonia, sustainable aviation fuel and other products, or Pipelines directly to hydrogen power plants and other users across the state.
▲ Hydrogen City project planning, picture from: Green Hydrogen International
One of the uses for green hydrogen is sustainable rocket fuel in plans announced by Green Hydrogen International, which is considering combining hydrogen with carbon dioxide in Brownsville to create a type of fuel for launch operations in South Texas. Green methane rocket fuel.
▲ Picture from: Green Hydrogen International
Brownsville is home to SpaceX's South Texas launch site, which SpaceX announced in 2018 would be dedicated to SpaceX's Starship launch vehicle.
▲ Picture from: VISIT Brownsville
SpaceX is currently developing a new rocket engine, the SpaceX Raptor, for the SpaceX Starship in development. The Raptor engine will use cryogenic liquid methane and liquid oxygen as fuel instead of the kerosene-based fuel the company has used so far .
When he founded SpaceX, Musk expressed his own space exploration destination-Mars. In order to complete the exploration of Mars, how to go and how to return are problems that need to be solved.
▲ Picture from: SpaceX
After rushing out of the earth and reaching Mars, the engine must generate enough specific impulse, and the upper limit of the specific impulse is determined by the fuel. After the exploration, returning from Mars to Earth, bringing the fuel for the return journey when starting, increases the load of the rocket, which is obviously unrealistic. Therefore, it is necessary to replenish fuel in the universe so that the rocket can return to Earth.
At present, the ideal rocket fuels should be liquid hydrogen and liquid oxygen, but the preparation and storage of liquid hydrogen are difficult. The freezing point of methane (about -182°) is equivalent to the boiling point of liquid oxygen (-183°). Compared with liquid oxygen and kerosene, the temperature difference between liquid hydrogen and liquid oxygen is less demanding on the fuel storage tank. , can also reduce the structural weight.
▲ Picture from: VISIT Brownsville
In addition, the specific impulse of the methane liquid oxygen engine is between the liquid hydrogen oxygen engine and the liquid oxygen kerosene engine, which can rush to Mars. What's more, there is carbon dioxide and ice in the Martian environment, which can be made into methane and oxygen, which means that, using SpaceX Raptor rockets, it is possible to refuel on Mars.
Renewable energy is undoubtedly the future development direction, and the hydrogen obtained by Green Hydrogen International using renewable energy has various uses. With GHI's hydrogen powering it, hopefully SpaceX's rocket will be a little quicker the day it touches down on Mars.
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