What a fascinating view back into the history of this subject.
Now we know what happened to the money appropriated for those weird little R&D projects that Congress worked into bills to appease the environmentalists.
It looks to be a very thin little ribbon of research winding its way from the 70's and through the 80's
Their concept of a PBR is fairly constrained--sounding like something designed for a spacecraft, on a long spaceflight. It's a neat idea, like a terrarium for algae, but with nutrient input and harvesting. ....Very high-tech.
But that is your point, I suppose.
Even the most low-tech options require a lot of high-tech materials and controls.
I'm surprised (but shouldn't be) that the algae is so sensitive and temperamental; ...and both to daily fluctuations and to seasonal variations.
Grazers feasting on the algae at various times was another factor that, while I've known about them, I'd never connected with algae as a problem--but of course, it is a problem.
...And all that optimizing of the productivity within the lifecycle and conditions....
...and the Harvesting problems!
Lots of hurdles and a few dead-ends....
No wonder this wasn't easily ramped up, way-back-when.
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I still can't help but think that at just about every step along the difficult path, they could have explored many other possibilities, options, or techniques. Every time they find results which they don't understand -is an opportunity for much more research (given enough funding and inspiration).
I know as a government project, they were probably limited in both funding and inspiration; and this story certainly sounds like a good example of how government can drive something into the ground.
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...some random thoughts:
It sounds to me like they need to create a simple ecosystem supporting various algal species, rather than maximizing a monoculture of algal crops.
I also think that they need to focus less on oil content and more on productivity.
Oil content rises in response to various stresses.
When they isolate a high-lipid species, it's already living in stressed conditions (for its normal preference).
Probably be pretty hard to cultivate under our "normal" conditions.
Get high productivity first, and then stress the algae to drive up the oil content.
At so many points they reach a "dead-end" and go off in another direction, without even rethinking the original problem so as to avoid the dead-end.
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Quotes
(& some thoughts) along the way:
Bioenergy pact between Europe and Africa
"the yield is limited by the amount of energy (sunlight) available – so improving the cultivating conditions follows the law of diminishing returns, as every percentage of yield that one can wrestle out becomes harder and harder as one approaches the theoretical limit."
But isn't this true of terrestrial plants too?
"while it may be theoretically possible to achieve growth rates that are up to ten times higher than the best terrestrial growth rates (in the tropics), the expenses associated with PBRs are hundreds of times larger than terrestrial cultivation, making PBRs economically illogical:"
"photosynthetic capture through PBRs, which are the most expensive extreme in the algae sector. Going down the expense curve, there are approaches - such as open ponds - that are less expensive; potentially there may be some optimum where microalgae cultivation becomes cheap enough yet with sufficient control over external conditions to secure reasonable yields. Open ponds, are still iffy in my opinion, however, they are not as absurd as PBRs."
"There is no question that microalgae have the potential for high productivity per area, albeit with all associated high cultivation costs."
...and nothing can be done about these "high cultivation costs." 
"This CO2 from emerging liquid fuels is in addition to the new cohort of coal-fired power plants that is coming online."
"When the world gets to actually doing something concrete and meaningful in regard to global warming, I strongly believe that the only option left would be to scrub CO2 from the air, I will be writing on that in the near future."
Yes, ...like with algae (but not focusing on high lipid content necessarily).
"
Concentrated Solar Power. It is a viable solar conversion approach and we will likely see CSP grow in significance.
CSP generates electricity, however that does not address the transportation sector, as the problem with electric cars is still their range. We believe that nanotechnology can play significant role in designing batteries with higher and higher energy densities so that electric cars charged on
CSP electricity can become reality. At AIBN we have several projects on using nanotechnology for improved battery performance."
"Realistically, I don’t expect that energy densities will ever approach these of liquid hydrocarbons, however, electric cars, in addition to lowering emissions have other benefits...."
"So, if you are to ask me today, what 'sustainable future' I believe has the best chance of succeeding in the long run, it will be electricity generation via CSP tied to electric cars for transportation. That’s something that could take 25-30 years to materialize in scale, but it has a shot."
0-0-0
http://www.nanostring.net/Algae/CaseStudy.pdf
"Liquid fuels or biogas can potentially be generated from biomass by pyrolytic, non-fermentative processes. Research on such technologies has been going on for more than 80 years, as it would allow the use of much cheaper feedstocks (grassy and woody residues, municipal solid waste, etc.), however, so far no significant commercial installations have been established. A major disadvantage of pyrolysis, when compared to transesterification and fermentation, is the high energy needs of the process. It requires external heating to 300-800oC, making it obvious that the energy ratios would be much worse than for fermentation or transesterification (we have not been able to find a study on pyrolysis with a credible energy balance in it)."
CSP??? How about using Concentrated Solar Power.
Well, I'm still reading. I read a bit and then go think for a while, imagining the past and wondering about all the potential futures that were not realized back then--so much potential.
But I'm still glad all this basic research was done. Even the failures are very instructive.
More later:
...and thanks again for the links!
~
Re: Algae.
