"If you can get usable oils from crops that can grow in unimproved soil that isn't good for much else, with little in the way of irrigation or fertilizer, you can come up in the positive numbers a lot easier than you can with high-maintenance crops like corn. "

Even better if you use the ocean instead of land. Better than that if you use an area of the ocean that normally makes hurricane, but because of the way you using the ocean it prevent hurricane from starting- or reduces it power. Two ways to do this, someway prevent evaporation or prevent evaporation by cooling the surface water.
Another more mechanical but related aspect is trying fiqure out how to harvest the top inch of ocean water which quite bit warmer the deeper surface water. This might resemble solar energy production similar to leaving black garbage in the sun. In your ocean energy production you would add stuff to ocean water that reduces evaporation and the water's surface tension. And you want cheap and quick way of grab square miles of ocean water which is about 1" deep- each cycle may be a couple hours in length allowing 4 or 5 cycles per day.