Two-stage process for producing oil from microalgae
A process for production of biofuels from algae can include cultivating an oil-producing algae by promoting sequential photoautotrophic and heterotrophic growth. The method can further include producing oil by heterotrophic growth of algae wherein the heterotrophic algae growth is achieved by introducing a sugar feed to the oil-producing algae. An algal oil can be extracted from the oil-producing algae, and can be converted to form biodiesel.
1. A process for production of biofuels from algae, comprising:
a) cultivating an oil-producing algae by promoting sequential photoautotrophic and heterotrophic growth,
b) producing oil by heterotrophic growth of algae wherein the heterotrophic algae growth is achieved by introducing a sugar feed to the oil-producing algae; and
c) extracting an algal oil from the oil-producing algae.
2. The method of claim 1 , further comprising converting the oil to biodiesel.
3. The process of claim 1 , wherein the oil-producing algae includes a member selected from the group consisting of diatoms (bacillariophytes), green algae (chlorophytes), blue-green algae (cyanophytes), golden-brown algae (chrysophytes), haptophytes, and combinations thereof.
4. The process of claim 3 , wherein the oil-producing algae includes Amphipleura, Amphora, Chaetoceros, Cyclotella, Cymbella, Fragilaria, Hantzschia, Navicula, Nitzschia, Phaeodactylum, Thalassiosira, Ankistrodesmus, Botryococcus, Chlorella, Chlorococcum, Dunaliella, Monoraphidium, Oocystis, Scenedesmus, Tetraselmis, Oscillatoria, Synechococcus, Boekelovia , or combinations thereof.
5. The process of claim 4 , wherein the oil-producing algae includes Chlorella, Dunaliella , or combinations thereof.
6. The process of claim 1 , further comprising introducing a nitrogen-fixing algae to the oil-producing algae to provide nitrogen as a nutrient, or using the nitrogen-fixing algae as the oil-producing algae.
7. The process of claim 6 , wherein the nitrogen-fixing algae consists of blue-green algae or cyanobacteria.
8. The process of claim 1 , wherein the sugar feed is the primary source of both carbon and energy in the heterotrophic growth stage.
9. The process of claim 1 , wherein the autotrophic growth includes enriched carbon dioxide.
10. The process of claim 1 , wherein the sugar feed is provided by cultivating algae and extracting the sugar feed therefrom.
11. The process of claim 1 , wherein the heterotrophic growth stage is initiated using a stress induction mechanism.
12. The process of claim 11 , wherein the stress induction mechanism includes at least one of light deprivation, nutrient deprivation, injection of a reactive oxygen source, and chemical additives.
13. The process of claim 2 , wherein the converting the algal oil to form biodiesel is by direct hydrogenation or transesterification of the algal oil.