algal biofuels DOH!

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Interesting piece of research from Cambridge suggests that the energy required to circulate algal cultures through the tubes of bioreactors will consume far more power than the cultures will yield. I'm a big fan of the concept of algal bioreactors and I think its disingenuous for New Scientist to have published this without considering the contribution to filling that power void that renewable technology could supply. Wind turbines are fairly inefficient things for converting wind to electricity but they are much better at converting wind to mechanical power, which could be harnessed to supply the necessary pumping. Obviously wind isn't reliable and so you could have a mix of backup technology such as photovoltaics and particularly biogas produced from the anaerobic fermentation of the organic mulch left over from biodiesel extraction.

The obvious problem is that all this adds greatly to the capital costs of the whole plant. However, as algal bioreactors will need to be situated near a source of CO2 to feed the cultures and preferably a source of grey water as well then locating water treatment works, conventional power stations and bioreactors together on the same site seems a "no-brainer" and this would lead to economies of scale and reduction in system duplication. This sort of integrated treatment/power generation site is clearly the way forward in sustainable technology. Combined with CHP technology and rubbish incineration a well-designed system could offer a complete sustainable technology hub for small to medium sized towns.

algal biofuels

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I had dinner tonight with a researcher visiting our lab, who works in the field of algal biofuels. He told me that they are far from commercial reality. The numbers you see in the press are extrapolations from lab studies and attempts to scale them up to commercial scales suffer huge losses in efficiency, producing ~20% of the frequently quoted figures, probably due to the need to keep the cultures on a knife edge balance between lethal stress and rapidly reproducing.

Eg.

"diatom algae needs silicon in the water to grow, whereas green algae requires nitrogen to grow^. Under nutrient deficiency the algae produced more oils per weight of algae, however the algae growths also were significantly less."

From here.

I can't help but be disappointed as I had fallen under the spell of the PR and was poising myself to spring into this line of research and save the world. I haven't abandoned that idea, I'm just going to have to work a bit harder for it. But then a slightly demented man once said "nothing that's worth having in this world comes easy".