Algae based biofuel is a new energy source that is in transition from the research lab into commercial production. Certain types of algae contain natural oils, up to 50% composition by weight, that can be distilled into a vegetable oil or a number of petroleum-like products. Algae grow naturally all over the world and can be grown in massive, almost limitless, amounts. Algae require water, sunlight, carbon dioxide, and a source of nutrition in the form of organic matter. Through the process of photosynthesis, algae pull carbon dioxide from the air, convert the organic matter to oil, and return oxygen to the atmosphere. The organic matter can be quite varied, including sewage and untreated waste. Oil can be extracted from the algae through a number of processes. The simplest and most popular method is an oil press, which is similar in concept to an olive press. It can extract up to 75 percent of the oil from the algae being pressed. Other processes, which required additional equipment and effort, can extract essentially 100% of oil.
The most natural method of growing algae is in open ponds, with ponds in hot, sunny areas of the world providing maximum production. However, this approach requires significant amounts of water due to evaporation and significant effort to maintain the ideal temperature. New techniques include vertical bioreactors that grow algae in large drums, either outside under natural light or inside under artificial light. These drums are gravity fed, experience no evaporation, and allow 85% water recycling. Bioreactor plants can also be strategically placed near fossil fuel power plants to capture excess carbon dioxide that would otherwise enter the atmosphere.
Algae-based fuels have a number of benefits over other biofuels:
- essentially carbon neutral since they process carbon that has recently been captured in the feedstock and utilize carbon dioxide from the atmosphere in the photosynthesis process
- relatively efficient in terms of energy yield per acre compared to other biofuels (e.g., soy or corn)
- can be grown on land otherwise unsuitable for agriculture or indoors
- can utilize organic waste as source of nutrition
However, there are still considerable challenges. In particular it is not clear yet what the ultimate cost per gallon of fuel will be.
Note: also see OWOE Cool Tech - Artificial Photosynthesis