system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why hasn't Algae Fuel caught on yet?

For those of you don't know, Algae Fuel is just that: Oil made from algae. It works just like gas or diesel when refined, meaning it doesn't require engine modifications, unlike ethanol. Natural gas, propane and ethanol all seem to very popular, so why isn't Algae fuel?
gpt
Interesting bit from the wiki:

> The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (39,000 km2), which is only 0.42% of the U.S. map, or about half of the land area of Maine. This is less than 1⁄7 the area of corn harvested in the United States in 2000.


Essentially, it seems it's coming down to commercial viability. Looks like operating costs are still too high for widespread adoption.