Algae is the new crude. It converts CO2 into triacylglycerol and can break down into a sludgy form of organic crude material (biomass), that can then be further broken down, chemically converted into ethanol and biofuel.
The question of whether algae will replace fossil fuels is the wrong question; the question is how much of earth's "oil producing" capabilities can be sped up by using algae?
"Well, it is a basically simple process that uses temperature, pressure, and time to accomplish the chemical conversions ... A lot of people think of fossil fuels as, you know, dinosaurs and giant ferns and things. There is some of that, but the bulk of the organic matter was algae. Gradually the organic matter converts into slightly different forms, which make up the material that comes out as crude oil or natural gas.”
"The US is the world's leading consumer of oil. We use over 350,000,000 gallons of gasoline every day.
It's very important that the number of fossil BTUs that go into a gallon of fuel be significantly less than the number of renewable BTUs that come out of that gallon. If it's not -- let's not do it.
We have about 133,000 BTUs worth of energy in every gallon of biodiesel. When you add up all our inputs we need to end up being less than 133,000 BTUs, or we probably shouldn't be making that gallon. (1 BTU ~ the amount of energy in one wooden matchstick)."