> converting petrol into sugar-based biofuel to burn instead of burning the petrol directly

The obvious question here seems to me to be, what if they just burned their own biofuel? How much would that increase the cost/price?

At least some of these operations have to be running at some kind of net gain. It's really about price in the end. I've heard breaking down switchgrass in giant vats with microbes is going pretty well.

Eventually at some future point, we will need large scale biofuels at least for jet fuel. Because however long we might draw it out, we will run out of oil (better yet, we choose to stop using it, but, you know). The market will pay whatever it takes. The problem right now is that this seems so far off in the future and so impossible to 'time' that markets don't care yet.