Algae fuel is a type of biofuel that can be made in many different ways. It is possible to use algae in the creation of everything from biodiesel to jet fuel using a number of interrelated techniques. The creation of algae fuel typically begins with the extraction of oils and other substances, or the gasification of the entire biomass. Gasified algae can be used to run a power plant, while algae oils are usually further modified to create various other biofuels. It is also possible to ferment the biomass and create algae fuels such as biobutanol and ethanol.
Biofuels represent a large class of substances that can be used to replace fossil fuels. These organic fuels emit carbon dioxide when burned just like fossil fuels, but they also sequester carbon dioxide while growing. This can result in no net increase of carbon dioxide in the atmosphere. Biofuels are also renewable, since they are typically made from plant biomass that can be quickly replaced. Algae is an energy-dense type of biomass that can be grown in far less space than other biofuel crops, such as corn, sugarcane and switchgrass.
Algae fuel typically begins with bioreactors that are essentially large tanks filled with a liquid solution. These tanks can be used to grow algae in the presence of sunlight, or in the dark depending on the specific process. It is also possible to feed algae with a wide variety of substances. Some processes use sugar, while others can make use of byproducts from nearby coal-fired power plants. The algae turns these various food sources into oils, sugars, starches and other chemicals that can be processed into biofuel.
It is possible to create many different types of algae fuel using various processes. One process involves the gasification of an algal biomass. In this case, the algae is harvested, dried and then subjected to high temperatures but not actual combustion. The compounds that are released during gasification can be captured and refined to retrieve methane and other chemicals, or they can be used to fuel a power plant directly.
Other varieties of algae fuel are derived from specific substances stored within the biomass. Oil is one substance that can be extracted from algae and then turned into biodiesel. It is also possible to ferment the sugars or starches present in the algae biomass. This process is used to create biobutanol, ethanol and other biofuels. Further processing, such as cracking, can be done to create aviation fuel.