I feel the need to point out this doesn't sequester much carbon, as the resulting fuel gets burnt and the carbon ends up in the atmosphere.

The remaining algae pulp gets sequestered in the soil. So it depends on how much oil gets extracted from the algae. This depends on the commercial viability of the algae species and the extraction processes used. I won't bother going into the details (since, as you imply, they depend on a thin web of assumptions and guesses), but if you are getting carbon credits for sequestering and getting paid for the carbon ash as a soil improver, then the commercials tend to favor a fast-growing algae that is only 40% oil, rather than a slow-growing algae at 75% oil.

So, actually, it is quite possible that in a commercial process quite a bit of carbon ends up sequestered (about 50-60%).

David C.