I've heard a number of people assert that sweet potatoes are more energy dense per acre, but it looks like that may only be true if you consider complex carbs, and even then there are contenders. They may also be talking about one particular strain whereas calorie per acre lists like to say "sweet potato".
Sugar beets appear to be higher than sugarcane, but they're under substantial threat and they don't like the tropics. Then there's palm oil, which is such an environmental disaster that it practically ranks as a humanitarian disaster. Then something called chufa (a nutsedge), something called sacha inchi (Inca nut, a kind of spurge), and cassava/manioch bringing up the rear barely ahead of corn.
But some of these have a lot of calories in the form of oil, which means two paths are required to convert it to fuel. From a health standpoint, flooding the market with a cheap 'waste' product from a particular food process has kind of been our downfall.
I used calories because it’s comparatively easy to find lists of staple crops ranked by calories per hectare, and it gets discussed among homesteaders, smallholders and permaculture people at regular intervals.
Conversion efficiency is going to give you proportional results. If you’re trying to determine how many miles your car or jet can go it’s not accurate enough. But if you’re comparing crops to each other it should be fine.
Doesn’t change the fact that you are either double processing or separating and processing. That lowers the efficiency and means you have two production lines you’re managing, with separate processes on each one. More kinds of inventory, more experts on staff.
Sugar beets appear to be higher than sugarcane, but they're under substantial threat and they don't like the tropics. Then there's palm oil, which is such an environmental disaster that it practically ranks as a humanitarian disaster. Then something called chufa (a nutsedge), something called sacha inchi (Inca nut, a kind of spurge), and cassava/manioch bringing up the rear barely ahead of corn.
But some of these have a lot of calories in the form of oil, which means two paths are required to convert it to fuel. From a health standpoint, flooding the market with a cheap 'waste' product from a particular food process has kind of been our downfall.