Creating a sustainable future for space

This century will see an explosion in space travel and access to space.

It is important that this is done in a sustainable way that minimises the impact on our environment. The fuel we use is a big part of this and we are ensuring that the Hypersonix scramjet will use a very clean fuel.

Scramjets generate thrust by combustion, but what makes scramjets special is they burn their propellant (fuel) at supersonic speed!

Also, as an airbreathing engine, they don't need to carry oxidiser like a rocket does. Very few fuels have been shown to burn fast enough to be used in a scramjet, which limits the available options.

Fortunately, there's an environmentally friendly fuel which UQ researchers have demonstrated can be combusted at supersonic speeds!

Figure 1 - The typical combustion process (NASA)

Common rocket propellants, such as liquid methane and RP-1, combust hydrocarbons to produce thrust.

Unfortunately some of the by-products of this combustion process are carbon dioxide and other pollutants. The impact has been relatively minor up to now because rocket launches have been rare, however this century will see launches to space become more and more commonplace.  The negative impacts of using pollution producing fuels will continue to accumulate unless alternatives are found.

At Hypersonix, the fuel carried by our scramjet is liquid hydrogen.

Hydrogen burns extremely quickly, so it's a very good fuel for a scramjet. What is also great is that the waste product after hydrogen is burned with oxygen is simply water (in the form of superheated steam)!

The very simplified equation below shows how during combustion in the engine, for every two hydrogen atoms (H), one oxygen atom (O) binds with them and also releases energy.

 

H + H + O = H 2 O + Energy!

Figure 2 - The by-product of hydrogen fuel combustion = H2O!

So the Hypersonix scramjet will use a very sustainable method of propulsion. Even the hydrogen fuel can be produced in an environmentally sustainable way.