Ethanol in Far Cry New Dawn is used to upgrade your home base Prosperity. These upgrades will then make it possible to craft better weapons, vehicles, get more health and other abilities. Fully upgrading Prosperity also gives you the My Little Fortress trophy or achievement.

Here's a breakdown of the 3 ways to get Ethanol

You get Ethanol by capturing Outposts
You get Ethanol from Supply Drops
You get Ethanol by delivering Tanker Trucks to Outposts

Below we'll go through each method in more depth.

Ethanol from Outposts

Reward: 100-450 Ethanol

This is by far the fastest way to get Ethanol. In total there are 10 Outposts. On the map you can see black smoke coming from them, which makes them easy to locate. If you capture Outposts in Stealth you earn Ethanol bonuses. After capturing an Outpost you can scavenge (reset) it. Resetting it gives you some extra Ethanol. Then higher level enemies will take it back and it becomes harder to capture again but you also get more Ethanol the next time you do it. Rank III is the maximum per Outpost and gives 300 Ethanol on capture (+150 for Stealth). You can keep resetting it as often as you like. In the early game it can be somewhat challenging. The best strategy is to capture every outpost once when they are Rank I. This will give you more than enough Ethanol to upgrade the weapons workbench at Prosperity and then you can tackle higher difficulty Outposts.

Ethanol from Supply Drops

Reward: 35-40 Ethanol

Supply Drops are randomly dropped from Airplanes. They have a red marker in the game world and yellow smoke coming from them. The supply drops are guarded by a small group of enemies. They are random, but you can simply travel to an animal hunting spot and stand around for 1-2 minutes and a Supply Drop will appear.

Ethanol from Tanker Trucks

Reward: 75 Ethanol

First you'll want to liberate an Outpost, then stand on a street near that Outpost until an Ethanol Tanker Truck drives by. Shoot the driver, steal the truck and drive it to the Outpost. The spawns are random but they should spawn within a few minutes. Keep in mind they are highly explosive so defeat any remaining enemies before you get in the truck.