Solid fuel
Solid Fuel is the third kind of Fuel besides wood and coal and is processed in a Chemical plant.
Besides being useful as fuel in all Burner devices, Solid Fuel is also used to produce Rocket fuel, which is a component of Rocket parts built in the Rocket Silo.
Recipes
Solid Fuel can be created from Heavy Oil, Light Oil or Petroleum Gas.
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When to use Solid Fuel as fuel
Coal and Solid Fuel production can both be automated, but each has advantages and disadvantages. Solid Fuel is made from oil, and oil supplies are theoretically infinite, since oil spots never run completely dry. However, coal is almost always used first, and if coal is plentiful on the map, it may not be worth it to switch systems over to an oil infrastructure just for fuel.
One unit of Solid Fuel has 25MJ of energy, over three times the energy value of coal.
Which Solid Fuel recipe to use
- Light Oil has the best oil to Solid Fuel ratio (1:1), and has little other in-game use, making it the best choice.
- Heavy Oil has a much worse ratio (2:1) and should be cracked into Light Oil first instead. The cracking process changes the ratio for Heavy Oil to 1.3:1, which is much better.
- Petroleum Gas also has a bad 2:1 ratio and should not be used to create solid fuel in most cases.
However, full tanks of Heavy Oil, Light Oil, or Petroleum Gas can back up and block the Oil Refinery from refining more Crude Oil. This can create a situation where, for example, you can't create Petroleum Gas because your Heavy Oil tanks are full. It's advisable to set up some Solid Fuel factories to relieve the pressure in cases like this, particularly once Circuit networks have been researched and the factories can be switched on automatically once liquid levels reach a certain amount.