Lipid-Extracted Microalgal Biomass Waste for Biogas
(WIREs Authors/Advanced Science News) To confront global warming, climate changes and a potential energy shortage, biodiesel received increasing interest as a substitute for diesel fuels in efforts towards sustainable development. Microalgae-derived biodiesel is a promising energy source.
The advantages of microalgae as a biodiesel feedstock are many, for example, efficient photosynthesis, high lipid content, efficient CO2 mitigation, noncompetition for farmland, toleration to wastewaters during the growth, less water footprint and more cost-effective farming than energy crops.
Microalgae contain substantial amounts of lipids (2–46%), carbohydrates (8–64%) including cellulose and starch, proteins (6–71%), fats and many other valuable compounds. The current obstacle for microalgal biodiesel development lies in its economics, because until now there has been no commercial large scale production.
It is reported that microalgal waste after lipid extraction occupy around 65% of the microalgal biomass.
Biogas production from microalgal residues is thought of as an environmentally sound way to achieve sustainable and profitable microalgal biodiesel generation.
(O)ther types of lipids (e.g., chlorophyll, phospholipid, glycolipid, etc.) together with carbohydrates (starch and cellulose), proteins and fats can be used to produce biomethane via anaerobic digestion.
The digestate rich in mineralized organic N and P can be either recirculated into microalgal production system as the nutrient source or sold as fertilizers. CO2 emitted during the biomethane production can also be supplied for microalgal production. Thus, the integrated production of biodiesel and biomethane, and the recirculation of nutrients and CO2, may result in an improvement to the energy balance and economic viability of the process. READ MORE Abstract (WIREs Energy and Environment)