Pulsed Electric Fields is an innovative treatment based in the concept of electroporation (or electropermeabilitzation). This, despite not being fully understood, can be briefly described as the permeabilization of a cell membrane, result of the application of an electric field to the cell. This effect is used to break the cell walls that contain the lipids used in biodiesel production. The application of the electric fields in short pulses avoids undesired overheating problems as well as saves energy. Further understanding in the electroporation process will probably lead to better optimization of the PEF treatment.
PEF units basically consist of three units: High Voltage Pulse Generator, Treatment Chamber and Control System. The characteristics of the pulse generator and the treatment chamber such as pulse shape, resistivity and chamber geometry are determinant factors in the process. The system can be directly applied to the algae medium (wet biomass), without a typical drying step, this advantage dramatically reduces costs and energy consumption.
The process starts with the product (wet biomass) pumped to the treatment chamber there, it is under the effects of the pulsed electric fields generated with the pulse generator. This step, which only requires a few milliseconds to have effect is where the electroporation occurs. Hence the microalgae membranes are opened and the lipids released. Finally, a solvent such as chloroform, ethanol or hexane is used to recover the lipids from the medium.
This process permits an enhanced extraction of lipids and, at the same time, has many benefits for the overall process. Is easily scalable for industrial production, it can treat the full algae medium without a drying step, does not harm other valuable co-products derived from microalgae and reduces the use of solvents (usually hazardous and expensive).
