Photobiostimulation of green microalga Chlorella sorokiniana using He–Ne red laser radiation for increasing biodiesel production

Microalga would be the paramount resource of biodiesel able of satisfying the world requirements for transportation fuels, which could fully replace the petrodiesel. Therefore, the research studies focus on developing novel biodiesel production methods. The present study investigates the effect of monochromatic light such as red light-emitting diodes (LEDs) and He–Ne red laser radiation on the accumulated lipid and the growth of the green microalgae Chlorella sorokiniana. The irradiation of microalgal cells with He–Ne red laser source which has a wavelength of 632.8 nm was hypothesized to enhance the accumulation of lipid inside the algal cells, which ultimately increases the biodiesel production. The photobiostimulating effects of laser irradiation on biodiesel was investigated by irradiating the microalga for a duration of 2 h with 632.8 nm He–Ne red laser source compared with 2 h irradiation with red LEDs and 2 h irradiation with white light (the control). The results showed that the oil content inside the algal cells irradiated with He–Ne red laser was 3.1 times the algal cells irradiated with white light (the control). Similarly, the biodiesel yielded from the algal cells irradiated with He–Ne red laser was 3.1 times the biodiesel yielded from the algal cells irradiated with white light (the control). However, the oil content and the biodiesel yield from algal cells irradiated with red LEDs were only 0.82 times those of the control. Therefore, it was concluded that the irradiation of microalga with red laser increases the biodiesel yield.