Fuel is needed to construct some items and to propel ships through Warp points. You don't need it to travel within a system. Improved and Advanced Fuel are used to construct items but are not used in fuel tanks (think of them as advanced lubricant rather than actual fuel).
There are three sources of fuel:
A fleet with built in Fuel Shuttles can perform a Skim order when in orbit around any planet. The best worlds are Gas Giants which will add 200 fuel per Shuttle to the fleet’s fuel tanks. Other worlds will give less than this (see below). A common practice is to set up a population group on a gas giant and set up a convoy route:
SKIM 999
OC 999 (group number) Fuel 99999
You can then move skimmer ships to the gas giant and assign them to the convoy route where they will use all their action points each turn skimming for fuel. You then set up a tanker to convoy the fuel to somewhere useful (a colony or a fleet on resupply duty at a Warp point).
If the world is a Gas Giant, skimming efficiency is 100% (IE -- 200 fuel). Otherwise, the atmosphere and ocean type are checked as follows:
| Atmosphere | Skimming Efficiency |
|---|---|
| Hydrogen | +50% |
| Methane | +50% |
| Hot Gases | +40% |
| Ammonia | +30% |
| Nitrogen | +20% |
| Chlorine | +10% |
| Carbon Dioxide | +10% |
| Oxygen | +10% |
| Ocean | Skimming Efficiency |
|---|---|
| Any Semi-Liquid | +40% |
| Any Liquid Gases | +20% |
So for example, a world with Ammonia atmosphere and Semi-Liquid Nitrogen Oceans would generate 30% + 40% = 70% on the fuel, or 140 fuel per skim.
So, you do not need a Gas Giant. Hydrogen or Methane worlds with Semi-Liquid oceans get you 180 per turn, which is still pretty good.
You can convert 1 Gaseous Element into 1 Fuel, just like converting any other resource. This is not very efficient and is really only worth doing if you have a lot of gaseous elements and are waiting for more advanced installations to be researched.
You start with the Fuel Refinery which turns 2 Gaseous Elements into 10 Fuel and costs 500 CM. Once you build a refinery, it will run each turn as long as you have the Gaseous Elements. When you research Improved CMs, you gain access to the Fuel Distillation Complex. It costs 500 Improved CMs and turns 2 Petroleum into 250 Fuel.
Next is the Fuel Purification Refinery. For that you need Improved Fuel, Improved Petroleum and Advanced CMs. It costs 500 Advanced CMs and turns 1 Improved Petroleum into 500 Fuel.
You can fuel your ships by doing a LC order over a population group with fuel in its stockpile or via the Resupply order. If a fleet is given a resupply order, it will transfer as much fuel as it can to any fleet that arrives at the same location or any ship that is built at that location. You should build a surface installation at your home world with a large number of fuel tanks, assign it to resupply duty and set up a standing order to transfer fuel from your home population group each turn to keep it topped up.
Content contributed by Raven Zachary from the SuperNova: Rise of the Empire materials by Rolling Thunder Games and Scott Vandersee's Draco Advice document.