I don’t know why, but each time a biofuel solution rises up from the masses of alternative energy sources, later there are news saying biofuel is still more polluting than fossil fuel. Now it’s time for algae biofuels to pass through the test of actual “alga-to-wheel” pollution.
Anna Stephenson, from the University of Cambridge, has modeled the carbon footprint of producing, refining and burning algae biodiesel. The computer model reveals that algae-derived fuels have four times the carbon footprint of diesel, which is something actually unbelievable, at first sight.
She links to the process of cultivating the algae in perspex tubes, where energy is needed to pump the algae around, in order to properly expose them to sunilght. This process, for a start, emits 320 grams per megajoule equivalent of fuel. Regular diesel takes only 86 g/MJ overall in all the processes: extraction, refining and burning.
“If you use tubular bioreactors, frictional losses mean the energy required to pump the culture around is so high that the biodiesel would have a much greater greenhouse gas emission than fossil diesel,” she says.
What Anna is saying, though, is that the biofuel in itself is not so harmful as it is the technology used to produce it. For example, a saving situation would be that where the algae would be cropped in open ponds, but the water evaporates too quickly in this case, otherwise the methods only accounts for a tiny 19 g/MJ of CO2. Also, the efficiency of this type of cultivation is far lower than that of perspex tubes.
A colleague from Cambridge has the solution (in fact, that’s why I think these figures had been released): growing the algae in a specially-designed system of tubes that contain baffles restraining the water and algae flow so as to create a swirling motion, and use only 4 percent of the energy classic perspex technology uses, while ensuring the algae is constantly mixed.
There are always better solutions to everything, and I still think our pyromaniac obsession has to stop sometime, and this includes producing and burning fuels from algae, crops or petroleum. Still, they’re a good solution for now, until we better develop our electricity infrastructure.