There are significant biological, chemical, and mechanical engineering challenges to the commercialization of algae energy. Some of the key challenges include strain selection, maximizing photosynthetic efficiency, increasing lipid production, devising efficient fermentation processes, reducing the costs of harvesting, drying, and extracting oil from algae, and scaling up cultivation, harvesting, and processing systems in a cost-effective manner. Overcoming these challenges will be necessary for algae energy to become economically viable.