Fire Analogue on Hydrogen Methane atmosphere Planet

Question

Okay to summarize I have a planet with an approximate atmosphere of 44% nitrogen gas, 30% hydrogen gas, 23% methane and 3% other trace gases. I am working on an intelligent alien race on this planet that needs fire to advance but oxygen is not present in the atmosphere so traditional aerobic fires wont be possible.

My question is basically what are some anaerobic alternatives that can serve the same function as aerobic fire on this planet? A traditional visual "flame" is not necessary. So long as the chemical reaction produces enough heat for cooking, metallurgy and is "relatively" easy to produce. Be it compounds found in mines, in the air or on the ground. No need to be conservative go crazy with possible anaerobic fires and assume the compounds needed exist on the planet.

Writing down the chemical formula would be greatly appreciated.

Answer 1

Monopropellants are fuels that do not require an oxidizer for combustion because the oxidizer is bound to the molecule of the fuel itself. For instance, consider a system of hydrogen and oxygen in which the hydrogen acts as the fuel and the oxygen functions as an oxidizer. Such a system would be called a bipropellant system, as the reaction would require a separate chemical species as an oxidizing agent, as opposed to a monopropellant system, which does not require any external oxygen (or any oxidizer, for that matter) for combustion. Hydrazine is the most commonly used monopropellant.

Hypergolics are combinations of two materials that ignite spontaneously without the need for an ignition source, and therefore do not require any oxygen. As they do not depend upon external ignition sources, they can be readily controlled, which makes them ideal rocket propellants.

Aerozine 50 + Nitrogen tetroxide (NTO) have been used in many American rockets, including The Titan II and Apollo Lunar Module. (Source)

Using solutions such as those mentioned above, the remaining issue is reducing the reactions so they don't burn explosively, which they're kinda wont to do. A fire retardant can be added to slow the burn. But I'll leave the specifics as an excersize for the reader.

Answer 2

A flame is entirely possible, if you have a tank of oxygen (or other oxidizer, like nitrous oxide) or a material that releases enough oxygen when heated.

However, while there's many organic fuel materials that break down into hydrogen, light hydrocarbons, carbon monoxide, and other volatile combustible substances when heated, most strong solid oxidizers consist of salts that release a few of their oxygen atoms when they thermally decompose, leaving a large amount of ash or slag behind. And even with those that don't leave ash, like ammonium nitrate or nitric acid, much of their mass is still substances like nitrogen that don't contribute to combustion.

So, fires will be things that consume relatively large amounts of oxidizing "fuels". In a methane/hydrogen rich atmosophere, they'll be very hot, and consume the oxidizers quite quickly. Also, quite a few of the suitable oxidizers are unstable or even explosive in themselves.

Alternative reactions that might be of interest:

• Formation of metal hydrides. This can be fairly exothermic.
• More reactive fuels like alkali metals or alkali metal hydrides (which would be stable under that reducing atmosphere) with water as an oxidizer. These reactions could also be used in emergency devices to generate hydrogen for breathing, analogously to "oxygen candles".