As a renewable energy source, the generation of biofuels is of great interest. Biofuels can be categorized according to their feedstock. The feedstock for first generation biofuels includes sugar, starch, vegetable oils, and animal fats. The feedstock for second generation biofuels includes non-food crops.
For second generation biofuels, non-food crops are converted into biofuels. Both the source of the biomass and the conversion processes for second generation biofuels are numerous. One example of a conversion process is anaerobic digestion. One by-product of the anaerobic digestion processes is carbon dioxide (CO2), a greenhouse gas. Concerns over emissions of carbon dioxide are well known.
One example of a source of biomass for second generation biofuels is algae. Algae contain oil that can be converted into a biofuel. Algae require the following three components to grow: light, carbon dioxide, and water. In order to generate algae to be used as a biofuels feedstock, the algae could be grown in multiple different types of environments as long as the above components are present. Algae can be grown in an open environment such as a tank or pond. Alternatively, algae can be grown in a closed environment such as a photobioreactor.
Due to the interest in the production of biofuels and due to the need to reduce greenhouse gas emissions, a way to integrate the above two biofuels processes would be useful. The present invention discloses processes for integrating photobioreactors with anaerobic digestion for the purpose of generating biofuels.