To replace the sequestration of CO2 emissions from burning coal, the algae would have to remain isolated from the biosphere for the next 100 million years or so. Burning algae products to generate energy releases the CO2 back into the atmosphere.

If the algae can really keep up with the coal industry's emissions, then there is absolutely no reason whatsoever to mine coal and burn it. Simply grow algae to power the world economy.

Even then, biodiesel is the wrong product to make from the algae. We can't afford the new investment.

Botryococcus braunii is a pelagic algae that grows in the Indian Ocean. Its various strains make isoprene oligomers with different average molecular weights, mostly centered around n=6. What matters most is that the dry weight of the most prolific strain is OVER 70% HYDROCARBON. This is algae truly is a fuel plant.

Oil companies could feed these hydrocarbons directly into existing refineries. Electricity generators could directly replace coal with them. Because the hydrocarbons contain no sulfur, nitrogen, metals or ash, most existing pollution abatement and catalyst guard investment could be shut down as unnecessary. This is a really sweet feedstock.

For more details and some economic background see the website:

http://alum.mit.edu/news/WhatMatters/Archive/200111/

Thank you