It's proven (or may as well be - they're basically just growing...

It's proven (or may as well be - they're basically just growing algae and refining its constituents, nothing uncertain about the basic principle of that), it's repeatable, it's probably/hopefully reasonably reliable, but the cost is a big question. AEB's method of cost and technology intensive production with higher output may or may not prove to be more cost effective than simply growing algae in a pond. We know it'll take less land, we know it'll produce more, we know there's a greater financial input to start it.

If they can produce oil at a comparable price to crude, they're laughing, they can scale up and make a zillion dollars. If it costs a heap more than crude they'll only be able to sell to a very small, keen market, and they'll be competing heavily with other almost novelty category 'green' energy.