One thing to think about: If you get something from a culture collection that produces 90% lipids, but is impossible to grow to useable biomass, does this help you produce algae fuel?
If you grow a native species that that produces 20% but grows like a weed you will end up with at least more than with the previous scenerio.
So the best thing is a local fast growing decent oil producer. High oil producers do exist in nature, or this whole venture would not be worth thinking about. They may take time and effort to find, but they are there (see the Aquatic Species Reports).
Some species grow fast, some do not. Some species produce lots of lipids, some do not. Finding a combination that of these two variables, and a species that likes your growing system will ultumately determine your oil production.
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Better a cruel truth than a comfortable delusion.-Ed Abbey