Algal Biodiesel: Fact or Fiction?

The following is a guest post by John Benemann. John has many years of expertise in biomass conversion, and previously co-wrote a guest piece on cellulosic ethanol. On the subject of biodiesel from algae, he literally wrote the book.

I originally wrote an article over a year ago in which I mentioned the potential of algal biodiesel. I still believe, as I did then, that biodiesel (or more broadly, renewable diesel) is a far superior fuel to ethanol for reasons I outlined in that essay. However, over the past year, the more I learned about the prospects of biodiesel from algae, the more it started to look to me like cellulosic ethanol: Technically feasible? Yes. Commercially feasible? Nowhere close, and the prospects don’t look good any time soon. (However, as in the case of cellulosic ethanol, I believe the technology has some potential, so the government should fund the research).

This was a bit disheartening for me, because I had high hopes that we had an option for replacing a large amount of our fossil fuel usage with this renewable option. I no longer believe that, and recent work by Krassen Dimitrov (PDF warning) had reinforced my doubts. When I read the guest post at The Oil Drum by fireangel, “Has the Algae Cavalry Arrived“, my first thought was “Nice work.” My second thought was, “I should have jumped on this and investigated thoroughly eight months ago when those nagging doubts started to creep in.” One nagging question I have had since I first read about biodiesel from algae is “Why would NREL terminate the project if the prospects really were good?”

But should there be any further doubts, here is a guest post from a man who knows as much about this subject as anyone else in the world. And he bears bad news for those who had visions of driving around in algae-fueled transportation.


I saw with some interest the guest post on “Has the Algae Cavalry Arrived” posted by Heading Out and written by fireangel about the claims being made by GreenFuel Technologies (GFT) Corporation. I have some standing in this matter, both as Manager of the International Network on Biofixation of Carbon Dioxide and Greenhouse Gas Abatement with Microalgae (operated by the Int. Energy Agency, Greenhouse Gas R&D Programme) and also as a researcher in this field for over 30 year. My comments here are my own, of course, and don’t necessarily reflect those of the GhG R&D Programme or others involved in the Biofixation Network. In brief:

1. The post by fireangel, based on the analysis by Dr. Krassen Dimitrov’s, is generally correct, although some details regarding algae physiology and mass culture are arguable. However, those would not change the general conclusions of this posting. Well done!

2. The claims for biodiesel production rates being made by GFT, among many others in this field, exceed anything based on biological or physical theory, as also pointed out in this posting. They are truly bizarre.

3. The use of closed photobioreactors (>$100+/m2) for such applications is totally absurd.

4. I am on the record as stating that this is “It’s bizarre; it’s totally absurd.” (see below article from the American Scientist last year, which quotes me to that effect. This was a correct quote, and in context).

5. Open ponds, at

37 thoughts on “Algal Biodiesel: Fact or Fiction?”

  1. The report was published by NREL with their own introduction that paints a perhaps somewhat too-positive picture in light of the actual data and results. Thus it should be used with some caution. and
    I am not aware of any work in this field done by Prof. Briggs at U. New Hampshire, outside from an old website that quotes the Aquatic Species Program Close Out Report. There is no basis for the projections he makes for very high biodiesel production rates.
    I believe Prof. Briggs took the
    somewhat too-positive picture
    from the Close Out Report, and used those to do his calculations. As I see it, the guy was mislead as opposed to misleading.

    It is interesting to note that even with these somewhat too-positive numbers, algal biodiesel is hardly a slam-dunk. In an open pond system, located in the desert as proposed by prof. Briggs, evaporation will play a huge role: there simply isn’t enough water to keep the pond from drying out.

    Wonder if algal production in the open ocean will work?

  2. I concur. I had a bit more high hopes for algal biodiesel.

    I’m beginning to think that for all bio-fuel processes the discussion should start from a theoretical thermodynamic optimum.

    If that is very promising, we can start thinking about tweaking the process, funding, research and major investments.

    Not that algae is useless, but the thermodynamic limits should be kept in the rear view mirror all the time, esp. when looking on past successes like “X0% increase in algae productivity, Y% y-2-y increase in fuel production, etc.”

    We would at least know, where the practical improvements will hit a ceiling, even if we couldn’t forecast when it happens.

  3. I agree with others. Algal biodiesel won’t work for a number of reasons:

    1) Bioreactor costs too high. To replace the feedstock from even a small conventional refinery you would need hundreds of square miles of bioreactors. At $60/barrel the costs would need to be on the order of $20/sq meter. About the cost of carpet.

    2) Open ponds don’t work. High evaporation loss, invasive species and difficulty in feeding CO2 rich atmosphere are just a few of the problems.

    3) Permitting. What might work in a research lab or in the minds of a venture capitalist will have a hard time making it through the NEPA analysis. One of my projects proposed a technology in use in over 60% of the existing plants in the world, proven safe with very minimal environmental impact. The permitting agency spent over 18 months and several million dollars on computer modeling, showing de minimus impacts. Still wasn’t good enough, an organized coalition of environmentalists and sportsmen killed it. Essentially we were told we had to “prove it doesn’t cause harm”.

    Imagine the problem with a non-native, algal species. At a minimum the enviros will make you study it for years before approving. I can see the comparisons to kudzu and zebra mussels.

  4. How about collecting algae in the ocean, that way we dont have the very high cost of alga productaion. Only a few percent of the ocean net primary production would be enough to replace oil needs.

  5. The problem with that is that those high-oil yielding algaes don’t do very well in the wild. They get outcompeted by native species. So, you would end up burning far more energy to collect and process the algae than you would produce.

    Cheers, Robert

  6. How about collecting algae in the ocean, that way we dont have the very high cost of alga productaion. Only a few percent of the ocean net primary production would be enough to replace oil needs.
    My idea would be to start by harvesting the dead zone in the Gulf of Mexico. That way you get renewable energy, clean up the environment (free of charge) and get renewable fertilizer. Now we just need financing…

  7. The most common species of algae don’t produce much lipid. The biodiesel species are called “micro algae” like the species Botryococcus braunii which produces slightly over 50% lipids by weight. Even 20% is considered good. Most common algaes produce 1-2%.

    Seperating the fat algae from the lean algae is a difficult task. In fact seperating the algae from the water is not easy. It requires either a chemical or biological flocculant or some kind of mechanical seperation. It is expensive and energy intensive, or both. Adding low yielding algae to the mix just makes the problem worse.

    Suppose you could come up with a strain of algae that was hardy enough to survive in open ponds or the ocean without being taken over by more hardy strains – what would the environmentalists think of letting it loose in the ocean?

    The Union of Concerned Scientists (remember them? they are all about consensus science – except when it comes to the safety of genetically modified foods.) would likely have something to say about it. I can imagine the environmental rallies now. Algal Biodiesel = FrankenFuel

  8. I don’t think growing high oil algae is feasible: you have to assume that you are going to get whatever grows fatest today (may be different tomorrow). So algal biodiesel is a bit of an oxymoron. Algal renewable diesel – produced by gasification/Fischer-Tropsch – might work, because you do not depend on high lipid levels.

    As I understand it dissolved air flotation (DAF)is the best technology for separating algae from water, though it would qualify for “energy intensive”. The trick would be to get as high a concentration of algal biomass as possible before separation.

  9. I thought about FT, but then you give up 40% of the energy just in the syngas step. You would be better off thermodynamically with fast pyrolisis, and then burning the syngas in a CCGT and the coke byproduct in a conventional boiler.

    It doesn’t yield transportation fuel, but it is renewable power generation. Likely the same technology with coal and carbon sequestration is a cheaper route.

    I am coming around to believe there are NO feasible bio alternatives on any large scale.

    For transportation I keep coming back to electric and off-peak recharge with nuclear or clean coal technology.

  10. fireangel,
    What is it you like about Aquaflow, other than their modesty? Seems like they have much to be modest about: their technology for using algal ponds to treat wastewater is as old as the mountains. And it does not sounds as if they have even identified the process they are going to use to convert the algal biomass to fuel. So, what’s to like?

  11. Hi Optimist,
    They are already using wastewater to produce biodiesels. The amount is a piddly 3 barrels per day in their pilot project I think. My reasons for liking them are because what they are doing on however small scale is sustainable and probably not capital intensive. I believe that replacing any significant portion of your energy usage with biodiesels is going to be difficult, that said I think post peak we will appreciate all solutions regardless how small.

  12. Open pond algae culture is frequently cited as the key controlling costs and making algae biofuel economical. It is always immediately dismissed based on concerns about evaporation and culture contamination.

    But does the nutritional algae industry not grow their product in this sort of open raceway system? They must confront these issues, particularly the contamination issue, which is probably more critical for them than for biofuel producers. How do they solve these problems?

  13. They must confront these issues, particularly the contamination issue, which is probably more critical for them than for biofuel producers. How do they solve these problems?

    I don’t know about contamination issues in the nutritional algae industry, but the high-oil algaes are not too good at competing. It is difficult to maintain high oil production, and when they go native the oil production tends to plumment. From what I have read, the way to get oil production up is to starve the algae. That may be difficult to do in a large open system.

    As an analogy, think of turning loose a group of poodles and a group of German Shepherds in the wild. The poodles probably would not survive. The German Shepherds might. The high-oil algaes are more like the poodles.

    Cheers, Robert

  14. King,
    Here’s an idea:
    1. Grow algae in an open pond.
    2. Put the biomass thru TDP Stage 1 only (aka Dilute Acid Hydrolysis).
    3. Put the monomers in an anerobic digester to convert much of it to biogas. (It might even be profitable to recover certain amino acids such as lysine.)
    4. The gas can be converted to electricity (you can even use a Fuel Cell for that) or liquid fuels via F-T.

    Well, you have to keep trying, don’t you?

  15. Check out this story.
    This outfit, Xl Dairy, is spending $400 million (and they are not seeking investors) to build an algae-milk- biofuel plant in Phoenix. They plan it to be off-grid. It is puzzling to me that this story was ignored in favor of the flaky algae promoter story. I am beginning to wonder if Oil Drum and other Peak Oil blogs have an agenda. Is the financing behind the PO blogs, and the people who edit them, transparent, verifiable and public record?

  16. Is the financing behind the PO blogs, and the people who edit them, transparent, verifiable and public record?

    LOL! What financing? I have no financing. Neither do I consider my blog a PO blog. It is a blog on energy issues, and often discusses resource depletion. But who I am is easily verifiable. I do not get paid to do this.

    Also note in your story that algae is going to be a future phase. Time will tell if they proceed. But did you read the essay here and understand it? If you did you should know that they won’t. On the other hand, an integrated approach does have a better shot at success than a stand-alone algal biodiesel operation.

  17. I think you are all missing the point with greenfuel. they are not building a algae production system, they are building a co2 absorbtion system. don’t compare it with open ponds, compare it with amine absorbtion. At $200/m2 and a$20/ton carbon tax they could take the lot of their production and chuck it in with the coal and come close to even

  18. Sorry to hear that algae biodiesel out as substitute fuel. But one blogger at least is thinking outside the box, while everyone else seems determined to
    perpetuate an very inefficient
    fuel system : forget the diesel dengine ready goal and produce what can yield a thermal fuel and make electricity. All cars and eventually trucks, will be electric before long. You’re trying to hit a future target that won’t even exist.

  19. “None are based on data, experience, reality or even a correct reading of the literature.”

    Perhaps, but they DO have something quite more valuable. Faith that it is possible and a willingness to try. A trait that seems somewhat lacking by the posters to this blog

  20. “forget the diesel dengine ready goal and produce what can yield a thermal fuel and make electricity. All cars and eventually trucks, will be electric before long. You’re trying to hit a future target that won’t even exist”.

    Yeah, but we can’t build nuclear reators in our garages.

  21. open ocean biomass production:

    international waters, where environmental laws virtually don’t exist. or some 3rd world country coast with lower cost permitting

    a continuous harvesting process, perhaps cables drawn between piers

    use wild kelp

    focus on biomass production for conversion to electricit

  22. There are a number of as yet untapped and poorly understood potential benifits that await a properly costed sytem. Consider the analogy of compound extraction.
    Water is a neccesary component of both algae farming, reticulated water supply, sanitation , sewage treatment and conventional coal powered power stations among others.
    So can be expected to exist in some form around areas of population as these are prerequisettes for same.
    A model algae plant will look at this and try (There is no technical obsacle) to touch base at all these points.
    Pre treated sewage with solids removed (put that in a barge) is now a transport medium, transporting recyclable high nutrient water to the algae ponds .The ponds may be a series of “billabongs” on route to the nearby coalpower station.
    Coalpower and others require a large body of water for heating, algaes require depending on species, a stabilized temp for maximum growth.
    Nutrients dep on variety.
    CO2 depending on variety
    sunlight ” ” “

    The very worst outcomes from any half baked version will supply clean water to the outflow.
    Once upon a world we would have dreamed of such a good outcome.
    In the pollution stressed greenhouse finite world we find ourselves in now, people seem to have fogotten that there are a lot of peripheral issues re proper stewardship and minimising other enviromental damage.

    A second stage in this compound algae factory bio remediation project will see the selected standard algae forms providing @20% by weight of oil (given high yeild extraction methods)with a large residual stream of high quality paper making material (more than a guess) or high protein feedstock for animals @20%+ .
    These nubers are a guide only and depending on the level of extraction and the area of focus, will trend more to one by product or another. – nb Valuble byproduct.
    Stage three sees further selection of spp with a view to extraction of toxic and later usefull compounds from the waste stream – now a valuable resource. – Phytomining .
    This resource will be carrying in a prcentage of all the minerals, nutrients and manufactured compounds including some very toxic that are now almost without exception finding their way to ocean outfalls here in Aus and much more commonly on a world stage into the next downstram populations water supply.
    This third stage would be sited at the various “billabong sited along the canal.
    Each of these little labs charged with assurring the suitability for next use. Packing and marketing of their component and even the sale or further product development
    This would leave a high quality water ready for reintroduction for downstream use or further treatment as necessary for
    general consumption or possibly a reverse osmosis membrane or other technology applied able high quality supply.
    This model demonstrates multiple testing steps wich should assure consistant quality assurance.

    The seuestration of CO2 is not to be measured as such bu any study in that context will reveal a 50% saving if CO2 is removed from flue gas( we dont know how much can be absorbed without further vstudy and spp. analysis)
    This 50% figure is derived from the fact that the CO2 gets to go around again.

    Students from the local high scools, colleges, prisons, universities or regular council employees would all be capable of understanding the system and the particlar aspect they are resposible for.
    Much like the local sanitation boards are now.

  23. In light of the above comments, I have just read where Solazyme and Imperium Renewables entered into an agreement for which Solazyme will provide algal oil to Imperium.

    Of course the $60/barrel question is how much quantity will they provide (they did not say).

  24. The Vertigro system of vertically hanging bladders is far more efficient than ponds for propagation of algae and has already established a 4000 gallon per acre of ethanol per year which is up to 20 times more efficient than corn and requires only barren land in well-lit areas, like deserts. I dare say this is better than the produce of a pond.

    Spokesmen for Valcent Products, said if only 10 percent of Arizona were utilized for this purpose, it could produce enough energy for the entire US.

  25. There’s been a lot of buzz lately about the Solazyme algal biodiesel process because they were featured in a new film premiering at Sundance. The information about their process is still kinda vague. Clayton Cornell over at the Gas 2.0 blog was able to get some info which makes me kind of skeptical of their process. Solazyme’s intention is to use sugar derived from a cellulosic ethanol process to feed their algae in indoor bioreactors. They would then extract oil from that algae and supply it to others to make their biodiesel. So, if the starting point is cellulosic material and the end point is diesel, why not just use a BTL process?

  26. Anyone looked at Ever Cat Fuels and their new procedure to produce biodiesel in a fixed bed flow-through reactor. The Mcgyan Process recycles the catalyst and alcohol necessary to make biodiesel, it reduces the reaction time from hours to seconds, and it doesn’t use water or dangerous chemicals.

    The process benefits seem too good to be true:

    1) Current waste products can be turned into fuel.
    2) No use of strong acids or bases in the process.
    3) Fast reaction times (seconds).
    4) Cheap feedstocks such as waste grease and animal tallow as well as a variety of plant oils can be converted to biodiesel.
    5) The metal oxide based catalyst is a contained in a fixed bed reactor thereby eliminating the current need to continuously add catalyst to the reaction mixture thereby reducing the amount of waste produced.
    6) Unwanted side reactions with free fatty acids producing soaps are eliminated, thereby reducing the amount of waste that must be disposed of properly.
    7) Insensitive to free fatty acid and water content of the feedstocks.
    8) Flexible feedstock; animal or plant sources of lipids can be used.
    9) The catalyst does not “poison” over time.

  27. I just landed up in your blog while browsing on algae related posts. And though this post has been posted last year, I couldn’t move on without commenting.
    You have clearly pointed out the key factors that shows algae biodiesel in a poor light. There are a lot of people who are waiting for that wonder cure. One can’t say for sure that algae would be the solution we hoped for, nor can one dismiss it as fiction.
    Before the world dug its way deep into the earth and found fossil reserves and then produced petroleum did we believe that it could be possible?
    I wouldn’t undermine the infinite possibilities that science is capable of.
    One just has to wait and watch.

    Vanessa@ Future of Engineering Blog

  28. I have several comments. I throughly enjoyed the read. I do not see how the enviromentalists can object to the introduction of a “Weaker species” of algea into a closed system like a wate treatment plant. It was even stated that when the algea goes native it is less useful. So if it ” Goes Native” Then what would be the problem. Not to mention the closed system. As for the Electric suggestion that some made. I would like to know how they intend to power an aircraft with Electricity. However there was a man that flew an old Soviet jet on Bio-Diesel this year. Ethanol OH Ethanol. I have nothing good to say about Ethanol. You get worse fuel mileage, your engine suffers more wear and tear and you wind up planting crops that are good for nothing else. Never mind the fact that it takes more energy to plant, Grow, Harvest, Transport, and Refine Ethanol than it produces. And all of the equipment used to perform those functions run on diesel. On the other hand I do not think anyone in the world would argue that every country is full of CRAP So if I can grow and algea that will help get rid of the physical crap/ not necessarily the other Crap that we are all full of, and produce a net gain in energy in the process…. I am all for it. I will even get investors to back the idea. I drive a 3/4 ton diesel truch and when I run it on BioWillie 80/20 or B20 I get 24 miles to the gallon Highway. And I assure you that if the cost of fuel continues to rise I will be more serious about seeking out Bio-Diesel options. Now I did not understand some of the Science sited in the early part of these comments, and I appreciate hearing a Pesimistic view on the subject but I think that this is a good start. It might not be the whole answer offered up with a tidy bow but Fossil fuels were not the magic answer either as we learned some 100 years later. I think that we should take every plant product that produse’s oil and see which one we can engineer to produce the most oil. Then that is the one that we should figure out how to grow in the most efficient manner possible. And then all of the otherones that are not used for anything else should still be accumulated and used. Here is were I have to go a little religous. God gave us this great bounty and if we do not use it effeciently that is our fault.

    Cameorn McSpadden

  29. McSpadden is wrong about ethanol. I am the only person I know in my locality that is actually using E85 in my car, and I have found it to be cheaper, cleaner, and hotter than gasoline, not to mention that is not imported. As far as engine wear is concern, study of a car run unmodified for 105,000 miles on E85 show much LESS wear than expected. Not surprising, since ethanol burns cooler than gasoline.

  30. Those who said Valcent got it right but they can produce much much more than 4,000 gallons of bio fuel per acre.

    NO CORN – 60 gal an acre
    NO SOY – 100 gal an acre?
    What-ever! Equals higher food prices and starvation.

    The only great source of bio fuel is through Valcent Products in Texas. They grow algae in a vertical, plastic, closed system that can attain 100,000 gallons of bio fuel per acre and uses only 5% of the water of other open systems. Also, who eats algae as a staple food? Go here and check out the Vertigro video.

    Using food sources to make fuel is insane when there is an alternative that can create enough fuel to power America’s auto needs using only 1/10th of the state of New Mexico’s arid, empty land.

  31. i agree with “the1pope”. the vertigro system looks very promising. even if there numbers are twice or 3x the systems real production numbers, it still seems economically feasable. did anybody happen to catch the cost (inital setup/operating) of this system? let me know, leave a comment on my site

  32. Hi, I arrived at this article and comments as it was linked from – where there was discussion of Botryococcus braunii (Bb). I have done a fair amount of research (for an amateur) on this microalgae and have written the majority of the Wikipedia entry on it. I disagree with the opinions expressed that algae-derived fuel is impractical. GreenFuels and all the rest, looking for a magic-bullet invention are what is impractical. I also disagree with the dismissal of PBRs (Photo Bio-Reactors) as too expensive — they can be made inexpensively, even at small scale, but there is little to 'invent' and less to patent. Because of the nature of the technology, it is stepwise refinement, rather than revolution, that will produce results. The only money I'll be able to make is, perhaps, a bit paid for an article on how to make an inexpensive PBR at home. And then, of course, the small amount of savings I will accrue in my purchase of hydrocarbons.

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