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 Mojo,

I believe that some people have extracted a little algae oil, but have not reported their results, so we do not have definitive answers.

With one exception, there is not need to dry the algae.  I assume it will save energy to not dry it.  The exception is to dry a small sample from time to time to have a valid test of oil percentage.

Another possibility is to use a centrifuge. 

I am hoping that we will be able extract the oil by reversing the osmotic pressure. 

Mojord, welcome,

For a number of reasons I don't think you will get to many responses to this question on this forum. Those who have extracted oil from algae are, at this point, mostly engineers or doctorate students who have commercial conciderations to work under and their results are not being published.

I have, as yet, not got aroung to extraction but will get there soon enough. You have missed a couple off your list - osmotic shock and sonochemistry or ultrasound.

With the three you have listed, Expeller will mix oil and water and you will have an emulsion that will need to be seperated. However being that algae are microscopic, you may have issues getting dry algae powder to flow smoothly through a press and the extraction percentages are not high.

Hexane - not sure of reaction with water but research leads me to believe this method needs dry algae.

Supercritical probably does not need to be absolutely dry as by varying the pressure and temperature you can fractionate the sample being extracted.

 In regard to osmotic shock, if you use a high saline solution to grow the algae, harvesting to a sludge and then dumping the sludge into distilled water will burst  nearly all the cells and you then skim oil off the surface.

Sonochemistry can be done wet or dry. If wet you will need to extract water from the mash before extraction of oils with a solvent.

I and others here have explained the processes in reasonable detail numerous times on these forums and I go into  detail in my" how to grow algae manual"

 go back in these forums and READ our previous posts or get the manual and READ or attend the Ecogenics algae production seminar and LEARN.and see it all firsthand.

there are too many  "open sourcers "that want to get into this field but there is a rule in life that is irrerfutable" you dont get something for nothing in this world.."  yet despite of this, I have offered answers to these questions in many of my posts here since 2004 and there are others here also who have  done the same by offering valuable information. yet despite of this, I see the same questions being asked over and over again.you want to do research to find things out,? go back through the archives on this forum.... seek and you shall find..its all in here somewhere.

marc

Thanks for the replies!

Very usefull stuff. I will post my results.

 I'm in the process of doing solvent extractions.  I'm growing neochloris and scenedesmus and have been extracting oil from those.  At first I was only getting 10-12% oil by mass, but stressed my algae a little and the oil content shot up to an average of  24.8%.  I have been comparing methods of preparation to lyse the cells before extraction and have found that extraction varies considerably depending on method used.  So far, the best extractions have been from algae that I crushed in a mortar & pestle.  (I averaged an extraction of 26% with the m&p compared to around only 9% from algae that was not lysed prior to extraction).  To make the cells shatter a little better I added dry ice.  I am not the biggest fan of this method since it takes so much work.  It takes at least 5-10 minutes of mashing and grinding to get the algae to look like a fine dust (finer than the raw algae itself).

The solvents I have used are hexane, butanol and ethanol.  Lately I have been focusing on butanol and ethanol since they are safer and easier for the average person to get, but have found some difficulties in using these solvents.  Both solvents extract chlorophyll so the oil goes from a green color to a dark brown color once concentrated.  There are methods of removing the chlorophyll using phosphoric and sulphuric acid but honestly, I feel like expanding the use of chemicals for processing is very much a dead-end, at least at the small-scale level.  I am not looking to produce oil for an "earth friendly" biofuel that requires several chemicals along the way for processing.  I should add that after each trial using butanol, I recovered 98% of the solvent for reuse because of its low volatility.

I have tried using a sonicator and it has been a little more difficult than I had expected.  The sonicator I have used is at least 15 or 20 years old so it is a little tricky.  I have to sonicate small volumes(10-20ml vials) and under the microscope, it appears that a large number of cells are not even broken after a full minute of high power sonication(about 100-125watts).  I sonicated some algae that I stressed by changing into a PBR with plain distilled H20 and extracted 35%.  Despite this promising number, I could only do one extraction that way because of the small volume that can be sonicated at a time.  Don't take that 35% too seriously because it was not replicated and could have been a fluke.  I will sonicate some more when I get a chance. 

To the extent of my knowledge, you definately need the algae to be in liquid form for sonication.  The way it works is by sending soundwaves through liquid to create tiny bubbles that violently implode.  The sonicator has no effect on dry algae whatsoever in my experience. 

I have always been most interested in figuring out ways to mechanically press the oil out of algae. The only problem I see so far is that algae is not quite the same as oilseeds.  The algae cells contain the oil, but it is a tiny amount of oil in comparison to the large amount of cellular matter.  Even when the cells are broken, there is enough algae powder that the oil is just soaked into the powder and can't be easily separated.  A french pressure cell is one way that algae can be broken by a press, and algae can be wet for this.  The french press creates a shear pressure that tears the algae apart as it is forced through a tiny opening.  There are other inherent problems with this such as the fact that these can get clogged up, and they may not be very good for high volumes.  Nevertheless, I don't think many people have looked into this and it is probably something worth checking out.  

Also, after grinding algae in a mortar and pestle, it doesn't appear that oil just comes out of the broken algae cells.  There is something else necessary to get that oil separated from the algae, which seems at this time to be solvents.  Even when wet algae is broken up, in my experience the oil didn't just float to the top of the water.  When sonicating samples, there was no oil observed at all.

 it may be obvious from my previous post but there are many solvents that can be used other than hexane.  although the ones I am looking at have extracted some unwanted impurities, there are many different types that can be investigated.  The expeller/press technique hasn't been shown to anyone's knowledge; that is just listed on many sites, including oilgae.  Those three you mentioned are listed on that oilgae site but there are much better resources for looking up ways of oil extraction.  Alot of organic chemistry-geared guides give a good overview of the options for lipid extraction.  One good site that gives a little bit of an overview is cyberlipid.org  The site isn't specific for algae, but that does not matter.  Any method of oil extraction can be investigated for its use with algae.  

Finally, someone who has gotten his hands dirty has made a post. For the most part, academic clean hands post here. Lots of book learned advice but little hands on experience is put out. I am growing botryococcus braun ii and it is slow going. My first objective is to keep the cells alive and thriving. Your posts are what I have anticipated. Thanks for the open comments regarding the difficulties in oil extraction. I believe your patience  wil pay off. If it was easy, it would already be done.

Finally, someone who has gotten his hands dirty has made a post. For the most part, academic clean hands post here. Lots of book learned advice but little hands on experience is put out. I am growing botryococcus braun ii and it is slow going. My first objective is to keep the cells alive and thriving. Your posts are what I have anticipated. Thanks for the open comments regarding the difficulties in oil extraction. I believe your patience  wil pay off. If it was easy, it would already be done. Have you considered a pressure device? My thoughts are that the pressure and heat might hold the answer. My reading on biomass and the breaking down of cellulose cell membrane point in that direction.

 That was my thought on the french pressure cell.  Look it up if you can; it is used in cell disruption and involves pressure and I am sure you can apply heat. The high pressure may create enough heat by itself, actually.  It is very much like a piston in a combustion engine, only there is a tiny outlet where the algae is forced out and torn by the sudden drop in pressure.  The problem is they are expensive and I don't think they are very widely used anymore.  I have met a few times with a cell biologist who worked as an intern at SERI during the ASP who can get his hands on one for me.

One of the main things I have learned so far is that the process IS slow going.  Even though the algae grow extremely fast once in the logarithmic growth stage, it takes alot of work to get to that point. I spent 2 months just trying to get enough algae to perform extractions and even then I  had to extract using less than a gram at a time to be able to replicate the extractions.  I don't want to sound negative though because I was able to grow algae, stress it to increase its lipid content, and extract a small amount of oil in the timespan of about 4 months.  Imagine what you can figure out in a year or two of this...  

Grtfulbuster  - thanks for the real world info!!! This is exactly what I was looking for. Real world problems.

Excellent work - I will keep you informed of my trials. 

Article

^*Correspondence to C. Largeau, Laboratoire de Chimie Bioorganique et Organique Physique - UA CNRS 456, Ecole Nationale Supérieure de Chimie de Paris 11, rue P. et M. Curie, 75231 Paris Cedex 05, France

Various water-immiscible solvents were tested for biocompatibility and hydrocarbon recovery under different contact conditions with the hydrocarbon-rich microalga Botryococcus braunii. Eighteen solvents were first selected from a database of 1500 compounds (compiled for solvent selection for ethanol recovery from Saccharomyces cerevisiae fermentation). Nine of these candidate solvents were shown to be biocompatible with B. braunii following short contact times. This biocompatibility tends to be associated with high molecular weights and high boiling points but strongly depends on solvent chemical structure. A low polarity is essential to biocompatibility and calculated octanol-water partition coefficients, or capacity factors determined by reversed-phase high-performance liquid chromatography (HPLC), are suitable predictors of biocompatibility with B. braunii. High recoveries of hydrocarbons directly from the algal culture require relatively polar solvents and are, therefore, inimical with maintenance of cell viability. The inaccessibility of weakly polar solvents to the cell surface appears to protect the algae but also prevents substantial recovery of the hydrocarbons stored in B. braunii outer walls. In order to achieve a high recovery, contact with the solvent must be carried out on algae concentrated by filtration. Then, a large fraction of B. braunii hydrocarbons can be recovered, after a short contact time, without impairing cell viability. Under these conditions, the pertinent solvent property is affinity for the nonpolar hydrocarbons, and the highest recovery yield, 70% after contact for 30 min, is achieved with hexane.

Hi Everyone!

I'm the new kid on the blog, I mean forum

Lately I've become more interested in bio fuels, especially from algae.  I've done a bit of research and tried some stuff, but I'm not getting any oil?!  I think all my procedures are right, but I end up with very yellow hexan, when I try to boil the hexane off (at about 80'C), I end up with yellow powder!

I suspect that my boiling temperature is way too high, and it should probably try 30'C.  Can any one confirm this?  Does any one know what the boiling point of algae oil is because I think that I'm boiling it off as well?!

Thanks everyone, looking forward to hearing from you.  I'll answer any questions I see as well, but I think everyone knows a lot more than I do:-)

All the best!

Plankton

Now distill the condenced combined fluids into hexene and the algae oil. Look up hexene for the boiling point of that fluid. The remainder is algae oil. The yellow powder has other uses from fertilizer to edible protien, depending on which algae oil was derived from. Some may even be used for ethenol. Lots of resources on internet search engines on all of this.

Boiling point of hexane is 69c. Yellow powder will most likely be carotene but that depends on the species of algae.

I hope you are using an enclosed and properly ducted cabinet when dealing with hexane. If not put your affairs in order and say goodbye to your loved ones.

Look into using a soxhlet unit to  extract the oil and distill off the hexane.

Centrifuge the balance to get rid of water. You should now have a clean sample of algoil.

Hi everyone!

Thanks a lot for the advice, busy working on it, will let you know what happens.  I have access to a rotary evaporator, through a friend, I'll try that out!

Thanks again!

 Hi everyone,

   Just joined this forum today so please excuse my ignorance, but i was wondering if anyone has tried extracting the oil by freezing the water and oil together.
 

 Ide,

As a production practice, that will probably be too expensive - cooling and then reheating.  As a lab exercise, it might work -  the freezing may rupture the cell walls - so, go for it.