Tad Patzek says biofuels are simply incapable of supplying current energy usage.
Krassen Dimitrov says algae is simply not commericially viable, and won’t be until oil is over $800 a barrell. I’m not sure how much credibility to give him though – he only talks about Greenfuel, and aside from a few very specific remarks about the Greenfuel patent, his criticisms are economic, not thermodynamic. He is also extremely light on with further sources and references.
A nice overview of research on the issue in the states is A Look Back at the US Department of Energy’s Aquatic Species Program: Biodiesel from Algae by J Sheehan, T Dunahay, J Benemann, P Roessler – Aqua KE Aquaculture Documents Library – Island Press. It’s publicly available via Google Scholar. Their estimate of the best possible price for algae derived fuel was double that of petroleum.
I’m still not convinced algae is not viable, particularly when there are solutions that accomplish multiple goals. See for example this New Zealand example of producing fuel from algae in sewage. We already need to process sewage – is viable to extract fuel, and perhaps sequester the leftover unusable carbon, from shit? How far will my piece of shit car run on a piece of shit anyway?
What if I bring my dogs into the picture – they produce roughly a kilogram or two of faecal matter a day. How awesome would it be if this incredibly nasty urban pollutant became a fuel source. The company doing this is Aquaflow Bionomic.
Andrew Leonard at Salon writes about this topic frequently.
And lastly, the title of this one says it all An in depth look at biofuels from algae.