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Emerging enthusiasm for biodiesel

  1. Jun 21, 2008 #1
    The emerging enthusiasm for biodiesel prompts me to consider the praticallity of capturing enough sunlight by photosynthesis in order to power the average car in central europe.

    Can any one tell be:-

    The average sunlight energy falling per metre of ground in Britain.
    How efficient the proposed plants are in producing usable oil content.

    The final crunch question - how many hectares/acres of crop would be needed to provide enough biodiesel to power the average family car for say 500 kms - averaged over a year to allow for overcast weather and seasonal growth.

    Any ideas ?

  2. jcsd
  3. Jun 23, 2008 #2
    Arizona example from Greenfuel online

    This is from the Greenfuel faq (greenfuel is one of the most successful at growing algae)(but keep in mind that no other form of "plant" is as photosynthetically efficient, some species of algae double their biomass in less than 24 hours, others, under ideal conditions can double every 6 hours, which is 2 to the 5th power in just 24 hours)

    Based on actual meteorological data from the ‘Typical Meteorological Year’ data (TMY) for Phoenix, Arizona, the average hour by hour Global Horizontal Direct and Diffuse solar radiation is 242 W/m2 (across 24 hours, 365 days), which converts to 5.81 kWh/m2-day (242 * 24 hours * 1000 kW/W). From the NREL solar database the average is 5.7 kWh/m2-day.

    Using the lower value of 5.7 kWh/m2-day, the total energy on a yearly basis is 2080.5 kWh/m2-yr. At 1 kWh = 3.6 million Joules, and 1 Joule = 0.002388 kCal, this is equivalent to 2080.5 * 3.6 * 10^6 * 0.0002388 = 1.79 * 10^6 kCal/m2-yr

    At 11% maximum theoretical photosynthetic efficiency, 1.97 * 10^5 kCal/m2-yr is available for photosynthesis, which is sufficient to create 51.6 kg/m2 glucose.

    The energy required to fix 1 mole of CO2 via photosynthesis is 114 kCal, or 686 kCal per mole of glucose created. 1 mole of glucose is 180 grams, so 1 Kg of glucose (as biomass) requires 3811 kCal of solar energy. Our proven productivity of 98 g/m2-day dry biomass at our Arizona facility in 2007 is equivalent to 36 kg/m2-yr productivity, which is 70% of the theoretical maximum, or a photosynthetic efficiency of approximately 7.7%. Since these results were achieved during the summer, when peak solar radiation is experienced, we would expect the annual average productivity to be somewhat lower. In fact, using the average monthly solar radiation of 8.0 for June and July in Phoenix, compared to the annual average of 5.7, leads to an expected annual average productivity of 70 g/m2-day based on our experimental data which is 25.5 kg/m2-yr, about 50% of the maximum photosynthetic efficiency.


    I do not know for sure, but I assume that their "proven productivity" factor is using the Vertigro system as they did at the Red Hawk power plant in Phoenix Arizona. They closed this demonstration facility because the algae grew so rapidly they were unable to harvest it as fast as it was growing. They called it a "successful failure", I seem to recall.

    Stafford "Doc" Williamson
    The Energy Circus
  4. Jun 23, 2008 #3

    Ivan Seeking

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    Welcome to PF winfotech. Note the avatar - I too am a huge fan of the algae option. You will find a number of discussions about this option.

    Here are a couple of the latest:

    Frankly, I think some designs [edit: bioreactor designs] miss the point as they would only be viable when fuel reaches $15 or $20 a gallon. But after studying this for a couple of years, it seems to me that the biodiesel-from-algae option is doable at scale, and for a reasonable price. And of course the DOE's Aquatic Species Program suggested that algae could be competitive as a fuel source when diesel passes [passed] about $2 a gallon. So at almost $5, it seems the time for algae is now.

    Could you fill us in on the latest on dewatering, oil extraction, and growth techniques, perhaps in the first thread linked? Of course I realize that much information is proprietary, but an overview of the latest would be nice.

    I have tried to start my own algae fuel company, and I can say that one of the biggest concerns about growing algae is that one must have the equipment to process large quantities, right from start-up. I was amazed at how quickly and easily it grew. When one does the calculations for the dry mass of algae produced by acres, it becomes clear that mass management is an issue.

    Also, are you using hybridized or engineered algae?
    Last edited: Jun 23, 2008
  5. Jun 24, 2008 #4
    Re: Biodiesel

    Ivan has some good points, that bioreactor designs often create elaborate geometries and difficult, if not impossible, construction challenges that make them impractical. However AlgaeLink ® has a couple of bioreactor designs that they claim are producing prodigious amounts of algae on a reliable basis. http://www.youtube.com/watch?v=eSBZa88fy64&NR=1 (this video has audio in Dutch but the visuals give a pretty good idea of some of what they are doing) We looked at those (the raceway ones even have a price list on the algaelink website) but decided that the area required meant huge amounts of land, so we set about designing a concentration system that was economical to build and manitain, like the raceway systems but had the advantages of the Vertigro vertical exposure to sunlight. (Vertigro's system is a sort of transparent "air matress" where algae and water flow downward snaking back and forth in narrow polythene bags, while nutrient nitrogen and carbon dioxide are bubbled upward through the same channels.)

    ASCII picture follows:
    ------------<--------- -<---------;
    etc., etc.

    As far as I am able to determine this is the Valcent/Vertigro system ( http://www.youtube.com/watch?v=_ToojK_MJd0&feature=related )that Greenfuels has been using. I should be clear that I have no connection to Greenfuels, except as an observer of the publicity about their accomplishments. My company has a division called DaoChi Energy of Arizona, which does the energy development work. We have some grand plans to establish waste-to-energy facilities all over the planet using algae grown on sewage for a biodiesel type product, plus recycled process heat for electric generation, and sewage sludge as a main feedstock for carbon based liquid fuels. However, as stated we do "development" work, and are still seeking to "package" ourselves into an alliance that has all the engineering, construction, and financial and political clout to make this all happen.

    We just received acknowledgment of receipt of our submission of an "Apparatus for the Cultivation of Phytoplankton and Other Autotrophic Aquatic Species" to the USPTO, so it is officially "patent pending" now. Our press release on this is at http://energy.psyrk.us/press/
    (that's pronounced "[The] Energy Circus")

    The design is a little crude, but inexpensive to build. (On the other hand, we haven't "designed" heating/cooling, cleaning & sterilization, or some of the other "niceties" into them yet either.) But we do achieve something equal to the spatial concentration of the Vertigro system, (Glen Kurtz claims he can grow 100,000 gallons worth of biodiesel per acre http://www.youtube.com/watch?v=8hioZ7C6HLs&feature=related so, although that may be optimistic and not entirely taking into account maintenance and other "challenges" that crop up, we should similarly be able to easily get 30,000 to 50,000 per acre per year, and possibly as much as Valcent/Vertigro) and we solve the "harvesting" problem (we think). Our design calls for hard permanent materials so we have operational cost savings in not having to repair/replace thin polythene bags, and no elaborate piping and valve systems like the Vertigro.

    Sorry, I don't mean to sound negative about the "competition", they have done some really good work, and I have been impressed with their results. see also: http://www.youtube.com/watch?v=8hioZ7C6HLs&feature=related

    Dewatering is a separate centrifuging process for us, (in multiple steps) but the most practical systems I have seen for "least energy input" are simple flotation methods using air bubbling up from below, (very fine bubbles) lifting the algae to the surface of the water/growth medium to be skimmed (manually or via weirs). We rely on the "stickiness" of the algae for initial separation, (like taking honey from man-made honeycomb frames in a bee hive) then have to centrifuge it (although we don't centrifuge the "honeycomb" equivalent pieces). We also have an non-patented, non-proprietary "trick" that helps speed things up in between those steps, but we're keeping that secret for now.

    On the other hand, I have heard discussed (though not seen, myself) projects that use ultrasonics for practically every stage of cultivation, separation, lysing, and oil extraction, and again in the "biodiesel" process for speeding up reaction times, reducing settling times by huge factors and in separation of diesel and glycerol. It sounds like a case of "when your only tool is a hammer, everything looks like a nail", but the guys at OriginOil (new company in Los Angeles) have several patents pending on these applications, and another company/group I talk to have other, similar patents pending on others (all using ultrasonics).

    One of the "cool" things that we were just "contemplating" as part of our designs but didn't include as part of our patent submission is using solar collecting concentration mirrors. I haven't looked into patents in the area, but we might use parabolic collectors that track the sun, reflecting onto a similarly gimbaled planar surface that redirects the gathered energy into a linear progression of mirrors to deliver the concentrated sunlight to the algae tanks. This came up because we were discussing with a client whether it might be possible to do algae cultivation indoors in Alaska, and we'd have to be redirecting light into the interior of the buildings. We later found a patent which proposes parabolic troughs of mirrors that reflect into what appears to be some kind of fiber optic tube (??), and is carried by the fiber optics to the growth medium. Very clever, but again, pretty expensive for capital costs.

    I don't know how much, if any of that is "new" to readers of these forums, but that's a quick thumbnail of state-of-the-art.

    Stafford "Doc" Williamson

    "I'm not a professional schizophrenic but I play one and his doctor on TV."
    Last edited: Jun 24, 2008
  6. Jun 25, 2008 #5
    Re: Biodiesel

    Thank you for the very comprehensive replies to my thread concerning Biodiesel. The main question in my mind concerns how much of britains energy requirements can be fulfilled by biodiesel - versus - how much of our production resources would be occupied in manufacturing it.

    Despite there only being a micro amount of biodiesel being manufactured at present it has generated a food shortage as more land is being used to grow the bio crop. There would seem little point in going down the road of manufacturing bio fuel if it means starvation on a grand scale.

    Except maybe for nucleur we must rely on the energy provided daily from the sun and this is finite. Doing a quick non-scientific "back of a cigarette packet" calculation - to rely on bio diesel or other non fossil resources would mean that we must use more than our existing land resources to harvest enough energy from the sun just to provide only our present needs without taking into account any future growth in population and requirements.

  7. Jun 25, 2008 #6
    Re: Biodiesel

    The food versus fuel debate is a public relations nightmare but it is just that; mostly just a scary imaginary problem. I don't know whose interest is served by perpetuating this myth, although it is a factor worth considering as we plan for the future.

    THERE IS NO SHORTAGE OF FOOD.** Less than 1/6 of the US corn crop went to ethanol in 2007 and even that also provides significant nutritional supplements to livestock diets after the distillers are finished with it in the form of what is called "dried distiller grains" (also known as DDG). Food prices have risen due largely to (1) systemic growth in food demand, especially previously non-industrialized countries improving economic situation which leads to more demand for better food, including imported exotic [foreign, to them] foods like wheat flour and corn sweetener. Add to this (2) the weak US dollar and (3) the huge price spike in oil (it now costs almost US$10 per US gallon of gasoline in Germany, Netherlands, and Britain). Some speculators are also driving up select prices as well. (and some panic buyers who absolutely "have to have" supplies). In the US, Oriental restaurants have been hoarding rice against any possible shortage -- Americans would stop eating at their establishments if rice was suddenly no longer on the menu, and they would be out of business.

    Corn is a poor choice for biofuels if it is just ethanol you are looking to obtain from the common starches and sugars, however, cellulosic ethanol from corn would be a huge improvement, and cellulosic ethanol in general uses the "whole" plant. So as long as you are leaving enough in the field/ground to grow subsequent crops it is far more efficient.

    But ultimately none of this comes close to being able to grow algae, which grows at rates that are so astoundingly high they sound like fantasies when you actually quote them. We are just not used to a crop "maturing" in one day, and certainly not doubling in mass in a matter of hours. Algae also grow in salt water (some species). They are the green slimy stuff that clings to rocks that you see as the tide goes out on almost every rocky shore in the world. Not all of them are "oily" but all of them have lots of lipids, even if only in their cell membranes, it is still a fairly good portion of their cellular mass, but some have 30 - 40%, possibly even 50% or more in lipid forms, and some even secrete oily substances that clump them together with their neighbors in addition to what is contained within the cells themselves.

    When you can take 5,000, 10,000, possibly even 50,000 gallons of oil from an acre (almost double that per hectare of course) it doesn't take a lot of land to achieve "energy independence" from fossil carbon sources, and since a great many algae species grow in salt water, you can even move a good deal of it off the land and into the ocean if you happen to be a tiny island nation. (I didn't say that any of this is "cheap", but again, with thousands of gallons per year per acre, the returns can justify the expense.)

    Now, none of this is to deny that solar, wind, tidal, hydro, and other sources can and will be important, but let's not let this MYTH of food vs. fuel already creating shortages dampen our enthusiasm for biofuels.

    ** Did I mention how Canada, Britain, Australia and the USA governments ALL have farm subsidy programs to pay farmers NOT TO GROW certain crops in order to maintain artificially high prices on those crops so that these countries don't become "farmless" and therefore dependent on foreign sources of essential foods? And then there are the trade barriers on importation of certain foods (e.g. try importing beef into Japan. It can be done, but the red tape, delays, and conditions make it NEAR to impossible.) If we have this kind of economic foresight with respect to food crops, it was a gross oversight to allow this to happen with energy resources.

    We need to get out of the deep dependence on any single energy type. That means we also need to be careful about becoming TOO dependent on electric energy, since all or at least almost all of solar, wind, tidal, geothermal sources get turned into electric energy to make it "portable" to the places where power is needed.

    Stafford "Doc" Williamson
    The Energy Circus
  8. Apr 2, 2009 #7
    Re: Biodiesel

    Typically algae doe not require exposure to sun light 100% of the time. One can use the sun light more efficiencly by pumping the algae with water through a glas reactor. 20 to 40 percent exposure should be enough. For a better understanding look at this design of photo-bioreactors for algae growth of what I mean.
    I think, this uses the incoming sunlight much more efficiently.


  9. Apr 2, 2009 #8
    Re: Arizona example from Greenfuel online

    Doc Williamson-
    Thank you for your very informative posts. Your value of 11% for maximum aquaculture photosynthetic efficiency is higher than the 5% to 7% number I have seen for agriculture (soil-based plants). Could the difference be in the lack of dark and photorespiration in aquaculture? Is your cycle based on anerobic bacteria, and does it evolve oxygen during photosynthesis (like Calvin and C4 cycle photosynthesis)? I agree with your value of 30 eV (calculated) heat energy content per molecule of C6H12C6 (monosaccharide or glucose). Your value of 36kg biofuel per m2 yr (360 metric tonnes/hectare-yr) is very impressive. What fraction of this is monosaccharide?
    Thanks Bob S.
  10. Apr 2, 2009 #9


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    Re: Biodiesel

    Could be winfotech numbers are already out of date, as he posted them over nine months ago :uhh:
  11. Apr 2, 2009 #10


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    Re: Biodiesel

    The energy efficiency of fixing carbon process aside for the moment is 25%:
    CO2 + 10 photons + H2O = CH2O + 1/2O2
    Only a portion of the received solar radiation is usable by photosynthesis, reducing the limit to 11%. Then other factors including respiration and other unavoidable issues block the usable PAR from reaching cells, reducing the maximum efficiency again to 3-6%. This last drop in efficiency might be addressed theoretically; practically it seems insurmountable.
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