for the simple extraction, make floculation ( NaSO4).

Solvent-Free Microwave Assisted Extraction (SFAME) technology looks promising. Although i'm not sure if it is currently being used to extract oil from algae.

ultrasonics look to be the most promising. not the best for small extractins.

what is the secret behind the quantum fracturing if it is a huge invention why is it not dependable revolution tool in the algal market.

compare to ultrasonic system and to the solvent system the enzymatic systems are not cheaper, better we research the mixing ratio of used solvents in order to recover a better fuel from algal cells.

What is wrong with hexane extraction
(other than it can go boom)?

Yes, it is a toxic solvent. But it has been safely used in soybean milling for 80 years. Any traces of hexane are easily removed by washing the oil and drying the meal. The oil and meal have been used in edible and feed products for 80 years. The salad and cooking oils we eat, the soymeal that goes into the chicken and pork on our tables, even the soyflour in our soymilk all come from via hexane extraction (except organic - a small fraction).

If it calculates, use it.

I must admit that ultrasonicification sounds cooler.

Greatest of energy consumptions comes from dewatering and drying process as a part of oil extraction. Wet extraction bypasses the drying step and hence could be cost effective and energy efficient. Processes such as filtration and pre-grinding to achieve even partial breakage of clusters typically takes dozens of hours of processing. Ultrasonication would be a better alternative. As ultrasound breaks the cell wall mechanically by the cavitations shear forces, it facilitates easy transfer of lipids from the cell into the solvent used for extraction. Use of ultrasonicators which create alternative high and low pressure would solve the problem of improper homogenization. The ultrasonicator also improves mixing and increases the chemical reactivity of the reactants. This would inturn reduce the time needed for the chemical conversion. Homogenization, combined with Solvent extraction gives better quality oil, making it easy for transesterification.

As a previous blog pointed out, liquified dimethyl ether looks like a good alternative - certainly better than neurotoxins, as Lucygreen pointed out. It would require high pressure for the normally gaseous dimethy ether to be a liquid, but when the extraction has been done, returning the pressure to normal would turn the solvent back to a gas, allowing it to almost entirely be reused continually. The high pressure required seems to be the only potential problem, but it's not like it hasn't been solved for many other situations

I think the use of hexane must be banned especially if the meal is used as feed. I would rather go for expellers which can extract 70% oil rather than take chances with a neurotoxin.

No Anna, supercritical fluid extraction will be the future of algal oil extraction. It is very efficient and the oil diffuses out rapidly.

I think enzymatic extraction is safer and more effective. But efforts must be made to make the process more economical.