| Green oil from algae |
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A team from the Central Research Institute of Electric Power Industry (CRIEPI), in collaboration with the Organization for the Development of New Energy and Industrial Technology (NEDO), has developed a new method for making the “oil raw green "from microscopic algae. The use of dimethyl ether (DME) in the process of extracting oils allows substantial energy savings compared to a conventional method. The resulting oil has a calorific value of 10,950 cal / g (45 792.9 J / g - of the order of calorific value of petrol and diesel).
The algae naturally contain heavy oil and light they synthesize during
photosynthesis. It is from what they produced the "green crude". The
extraction of oil is complicated by the fact that algae evolved in an
aquatic environment, and they therefore have high water content. Until
now, the algae were centrifuged and then pressed or dried sun or in an
oven to obtain a powder these processes do not destroy the cell wall,
hence the need to use organic solvents to "break" these walls and thus
extract the oils. The set to these processes, complex, carries with it a
large consumer of energy
CRIEPI's new process is based on the use of DME chemical formula
CH3OCH3. It has the property to bind readily with oil, while mixing
partially with water. It can cross the cell wall (mainly consisting of
water) to bind with the oils extracted.
In their experiments, researchers have used 6.65 g of algae previously
dewatered by centrifugation to remove 9% of the water. They were then
circulated for 11 minutes DME liquid at a temperature of 20 ° C a
pressure 0.5 MPa, and a stream of 10 cm 3. They extracted 0.24 g of
"green crude" (40.1% of the mass of the material dry). The previous
process is capable of extracting only 0.6%. DME and oils are separated
by expansion which causes the evaporation of the solvent (its point to
boil is at -23 ° C) which is recovered and reused. It is also possible
to evaporate under high pressure at a temperature of 50 ° C.
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