The algae have been researched for a long time already. The problem is that the most productive species are also the easiest to get a disease. It's a trade-off in a sense. Use energy for oil production or use it for defense and fight your enemies. So either the efficiency is not there, or it doesn't scale up well. In the end, it's just too costly.
Also I'm not sure about a sandwich built from weed ;)
But who knows, maybe there will be a breakthrough enabling commercial production. Using bio-ethanol is very compatible to current gasoline so it's very attractive from that point of view.