After $100 Million, Exxon Backs Off Algae as Fuel

[Scootaloo]

7. It's not magic

The algae is the waste. it's harvested and processed to create a sort of crude oil scum that is then further processed to produce biodiesel. It's another biomass scheme that uses water pools instead of fields. It's more efficient than fields because you're filling a volume rather than a plane with the biomass, but it's still inefficient; each step of processing consumes energy, which detracts fro mthe energy budget of the fuel being produced.

As for the carbon... The algae do consume carbon as a part of photosynthesis - but as with all aerobic organisms, they also release carbon through respiration. What carbon is left is incorporated into the body of the algae; this body is the biomass used to produce the fuel; and that carbon is then released through the methods of refining and then burning the fuel. it is carbon neutral in and of itself... but then you ask yourself, what about the energy used to refine, process, and ship the stuff, is that carbon-neutral? And the answer is no. Biofuels are less carbon-positive than "traditional" fossil fuels, but the atmosphere still collects a net gain of carbon through their production and use.