Please Explain How Algae Biodiesel at $9 to $40 per Gallon is Economically Viable?

Currently regular diesel is going for around $2.50 per gallon. A new study, Algae 2020, reports:

Based on the examination of several algae business and economic models, the Algae 2020 study finds the estimated costs to produce algae oils and algae biodiesel today range from $9 to $25 per gallon in ponds, and from $15 to $40 in photobioreactors (PBRs) today. Reducing these costs are critical for commercial success.

Like many "green fuels" algae biodiesel appears to be a long way from economic viability. Not to worry - the Department of Energy is allocating $50 million in R&D funding to algae fuels.