Argument: Producing algae biofuel requires too much energy

Issue Report: Algae biofuel


“Leave the algae alone”. Low-tech Magazine. 4 Apr. 2008 – Again, are algae producers considering the extra use of energy that arises by the capture of the CO2 when they claim that algae can deliver 100 times more energy than first generation biofuels?

This seems very doubtful. All these claims have one thing in common: they focus only on a small part of the total energy conversion chain.

A very good example is the story of Solazyme, a company that cultivates (genetically modified) algae in non-transparent steel containers, similar to those of breweries. In this case the algae do not get their energy from the sun, but from sugar that is fed to them. This method, says the company, makes them produce 1,000 times more oil than they do in sunlight, because sugar is a much more concentrated form of energy than sunlight.

But, where does the sugar come from? The researchers simply leave that part of the process out of their calculation, and nobody seems to care. Growing sugar cane of course requires significant amounts of energy, land and water. In fact, by turning off photosynthesis, the researchers eliminate the only advantage of algae compared to other plants: their higher energetic efficiency. The photosynthetic efficiency of sugar cane is not even half that of algae, which means that if the whole energy chain would be considered, this process can only be worse than that of algae produced in transparent bioreactors.

“Three Big Problems with Algae”. Oilgae. 23 Oct. 2006 – “1. Harvesting algae is much more difficult and energy intensive than most people realize.”