Open raceway ponds or closed photobioreactors and harvesting by the use of centrifuges or membranes. Additionally, oil extraction is possible either in a mechanical way (e.g. press) or by the use of solvents. For the stage of product recovery there are numerous technologies such as countercurrent chromatography, membrane processes, distillation columns and supercritical extraction. The challenge is to select the most suitable and efficient technology to apply depending on the microalgae and the selected products. The open raceway pond is a closed-loop recirculation channel with a depth of 30 cm. It includes a paddle wheel, which mixes and circulates the stream, as illustrated in Fig. 14.3. Open raceways are more economical than closed systems in microalgae tillage (Huntley et al., 2015) and have been used since the 1950s (Borowitzka, 1999). However, configurations must be very carefully controlled for these systems. Controlling the temperature, evaporation rate, and lighting within a diurnal cycle is very difficult in open ponds, and this would affect the cooling process (Chisti, 2007). Generally, open ponds have low yields and are not usually satisfactory, due to some problems such as losing water by evaporation, more energy requirement, unstable microalgal populations, and the difficulty of distributing nutrients