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Question for Blake on post Oct. 1 early a.m. 28

Blake where did you get the number of $150 per square meter for a cost for a modern PBR?

A square meter is not a good way to compare ditches with a PBR.  A more accurate way of comparsion would be to use gallon capicity and production per gallon per day.

If you compare a square meter of ditch surface to a square meter of PBR surface, yes, the PBR will cost more per meter of surface area.

Lets say the ditch has an effective production debth of  four inches and of coarse only works less than fifty percent of the time.  The modern PBR could be 40 feet deep and be lighted all the way from the top to the bottom.  And it will work 24 hours a day with flashing, color specific LEDs that are only on 10% of the time in micro bursts of photons.

Now take 40' X 3 = 120 square meters of reactor producing algae under perfectly controlled conditions.

Oh yes, did we forget that this operates 24/7/365.

So we gain another 12 hours per day on the ditch.

So now we are up to 240 effective square meters 4" deep and we are compareing that 1 meter of PBR surface to 1 meter of ditch surface.  Hardly seems fair.




Fri October 01 2010 10:13:48 PM by SAMDevelopment 3315 views

Comments - 19

  • Shankar wrote:
    Sat October 02 2010 12:02:05 AM


    I am impressed with your observation that it is better to look at per gallon for a pbr than per sq meter.

    Blake's statement was
    " The capital cost for photobioreactors is at least $150 per square meter, approximately ten times the cost of open pond systems . The actual current best yields as reported are under 0.5 gallons per sq meter. The problem is the capital cost of $150 to produce at best 2 gallons of fuel a year."

    I am not sure what is objective of his statement is !

    However, it appears that he is looking more at the algae industry as a whole and is talking about its unviablility as of now than as you assume.

    In my opinion he is not comparing a pbr to a open raceway pond.

    Anyway let us hear from him.

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  • Sat October 02 2010 04:42:57 AM

    Shankar, thanks for your comment.

    If my reply is read carefully one will see that a square meter of surface area, as Blake defines it,is going to produce .5 gal. of oil per year in either the ditch system or the PBR system.

    I am saying that a Modern PBR system will easily produce 240 times that amount (.5 gpy) if the PBR is 40 feet deep. So 240 X .5 = 120 gpy/1 square meter of a modern PBR. If as Blake says, a ditch system can be built for $15 per square meter it's going to be hard to pay for a system that has a life of only 5 to 10 years with only .5 gpy.

    A modern PBR has an expected life of 30 years.
    With a conservative 120 gpy yield per square meter of surface area, ROI is attractive.

    Alan Schaefer

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  • Sat October 02 2010 07:11:36 AM

    Very interesting and quick observation Alan.

    You are right in saying that the PBR has now reached pretty high efficiency and much longer life than before.

    I am not sure Alan, if Blake has said that he can build a ditch at $ 15 per sq meter. He has not said that.
    Anyway let us await Blake's reaction.

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  • Monterio wrote:
    Sat October 02 2010 07:13:25 AM

    U mean a PBR is 240 times more productive, besides giving light at nights and during winter days and protecting against contamination ?

    That is saying a lot !

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  • Sat October 02 2010 10:39:30 AM

    Mia and Monterio,

    Mia, Blake does say that it costs about $150/m2 for a PBR. Blake does say that a ditch costs about 1/10 of $150. That guess is $15 for the ditch system.
    I think he may be a bit low on both numbers on a commercial scale, but he said the numbers were just a good guess.

    To make his point his numbers are fine.

    As they say, 'don't compare apples and watermellons'.

    Where Blake and many others run off the track is
    when they use surface area instead of volume when trying to compare the production of ditches and PBRs.

    Another way to look at my answer of 240 times productivity PBR vs. ditch on surface area is to say it would take 240 square meters of ditch surface area to equal the production of 1 square meter of PBR.

    Now you people do the math and tell me which system is expensive.

    We haven't even factored in the land requirement and piping and etc. An emitter of 25,000 cfm of CO2 would require ~14,000 acres for a ditch system. That is 21.875 square miles!

    (14,000 acres divided by 640 acres per square mile = 21.875 square miles.) Think of the pipeing
    the water loss, the roads, the land cost, and how are you going to find level land close to a power generator? What about the power for the pumps to move the water/algae mix to the processing point and then the recyled water back out to the right ditch. All of this for an idea that only works 50% of the time???? What are you thinking of?

    Algae has to be done on a really big scale for two obvious reasons.

    1. The emitters are big! If your system can't handle the big emitters, and make a big profit, without govt. help, you are not in the game.

    2. Farming algae is loaded with pitfalls. Murphy is alive and well. "If something can go wrong, it probably will".
    So that means one must build a system that can eliminate as many high risk production foul-up
    points as possible. That is very hard to do in a ditch system.

    What do you think?

    Alan Schaefer

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  • Sat October 02 2010 09:40:27 PM

    Alan Schaefer

    I correct myself. Blake says that a ditch costs approx $ 15. You are right.

    Isnt it obvious that one must use volume and not area to measure, be it a open raceway pond or a pbr ?

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  • Sat October 02 2010 09:43:41 PM

    "ROI is attractive" is very un Alan Schafer like statement.
    One needs to work that out to the last penny, for different conditions.

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  • Manohar wrote:
    Sat October 02 2010 09:49:55 PM


    YOur arguement is well founded and well understood.

    Can u help me understand the math for a 100 T per day cement plant.
    How much CO2 and other pollutants does it bellow in a day.
    How many PBRs are needed to absorb them.
    How much of land is required for this?
    Approximately how much of land is required if we were to go by open raceway pond method ?

    What will be cost of PBRs ? ie capital cost ?
    Wha twill be the cost of open raceway ponds?

    What will be the operating costs ?
    Let us do all this for a 100 ton per day cement plant?

    And all can be done approximatations.

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  • Anna wrote:
    Sat October 02 2010 09:52:06 PM

    Alan Schafer

    I notice that you are building a 9500 gallon PBR.
    So for the above suggestion let us assume that we make a 10,000 gallon PBR. It will be easy to do the math :-)

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  • Larsyn wrote:
    Sun October 03 2010 02:08:46 AM

    Was the contamination factor taken into the open raceway cost. Besides its production figures fluctuation due to temperature variatition summer to winter.

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  • Manohar wrote:
    Mon October 04 2010 05:42:26 AM

    240 times more efficient
    x 2 because it works in the nights too
    = 480

    150 as it works in winter too.

    ? how much to add for contamination protection ?

    We need some math here.

    I have sent some messages to Blake in vain.

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  • Wed October 06 2010 05:10:47 AM

    Blake, thanks for continuing this discussion.

    Do youi understand where Mr. Rapier makes two big mistakes in his statement as you quoted in the above post?

    1. He asumes that a PBR is lighted by the sun.
    This is wrong. Algae only can use 2.5% of the
    full sunlight spectrum. Why stress the algae
    with all those extra photons. Give the algae
    only the right wave lengths, which are well

    2. A PBR can be, must be,many feet deep, and be
    lighted with LEDs all the way to the bottom.

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  • Shankar wrote:
    Wed October 06 2010 09:25:02 AM


    Rapier and his Rsquared are well known blogs in the internet and are a great source of information for all energy and particularly renewable energy enthusiasts.

    Everyone, including me who is not a techie and a pure investor knows that a PBR doesnt get sunlight directly and that all PBRs or atleast most advanced PBRs are lit manually.

    I would put it well within Rapier to know this.

    @ Blake
    can u give the url of this Rapiers article ??

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  • Wed October 06 2010 10:26:13 AM

    Shankar, My answer to Blake was based on Blakes quote of Mr. Rapier. I had nothing else to work on. Please go back and read the words of Mr. Rapier as quoted by Blake.

    "Optimistically, the very best yield you are ever going to getfrom that square meter, based on the amount of sunlight that algae can convert into biomass, amounts to less than 2 gallons. (per year??) The actual current best yields as reported in the literature are under 0.5 gallons per square meter."

    From this quote it is quite clear to me that Mr. Rapier is saying that he expects the PBR to be light by sunlight, and many are, and he is measuring production per square miter of surface for both systems.

    I can only comment on what he wrote and if you carefully read his quote you may come to the same conclusion.


    Alan Schaefer

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  • Manohar wrote:
    Wed October 06 2010 02:28:44 PM

    Alan, Blake, shankar, mia, luis, et al

    the actual url of Blakes article is


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  • Wed October 06 2010 08:36:13 PM

    Alan is right. Whether the author is well known or well read, in this instance by stating and comparing the open system with a pbr at per sq meter, the author is at fault.

    Rapier has given the reference of one
    " Abayomi, A., Tampier, M., Bibeau, E. (2009). Microalgae Technologies and Processes for Biofuels/Bioenergy Production in British Columbia. Retrieved May 2, 2010 from http://www.bcic.ca/images/stor?..report.pdf."

    But in their article there is no mention of
    " $ 15o per sq meter "

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  • Shankar wrote:
    Thu October 07 2010 12:14:47 AM

    I too agree with Alan.

    We need to point this to out to Rapier and seek an explanation.
    May be we should refer the url of this discussion of ours as
    to Rapier so that he can see the interest his article has generated and clarify as to from where did he take from Abayomi.A 's paper " $ 150 per sq meter .. "

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  • Mon October 11 2010 03:59:12 AM

    Dear FOA,

    I read the press release that Blake quoted. He did an accurate job of quoting the PR.

    I think that the error comes from possibly two sources. First it is a press release and they are seldom 100% accurate. Second, they are using very small amounts of dry algae. They started with a sample of 6.65g and that contained 91% water. From this sample they extracted 4.12g of water and 0.24g of "Green Crude Oil" this(corresponds to 40.1% of dry weight) with their DME technology.

    Then they tried, presumably a very small sample, some type of "traditional" method and only removed 0.60% of the dry algae weight as oil.

    Then they take a giant leap...."In other words, the method using DME was capable of extracting more than 60 times the 'Green Crude Oil' compared to traditional methods and demonstrated a far superior extraction performance as an extracting agent."

    The only rational conclusion that can be made is that they did a p--- poor job of applying "traditional" oil extraction methods.

    Alan Schaefer

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  • Shankar wrote:
    Tue October 12 2010 01:45:50 PM

    Alan and others
    I wrote to Robert Rapier and got a reply from him.
    here is his reply.
    Robert Rapier to me
    show details 11:55 AM (7 hours ago)
    Hi Shankar,

    The reference for that claim of $150/square meter is:

    Abayomi, A., Tampier, M., Bibeau, E. (2009). Microalgae Technologies and Processes for Biofuels/Bioenergy Production in British Columbia. Retrieved May 2, 2010 from http://www.bcic.ca/images/stories/publications/lifesciences/microalgae_report.pdf

    Cheers, Robert
    - Show quoted text -

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