Algae Based Biofuels

Algae are small aquatic organisms that convert sunlight into energy and store that energy in the form of natural oils, with certain types of algae containing up to 50% oil composition by weight.The lipid, or oily part of the algae biomass, can be extracted and converted into biodiesel (or algae fuel) through a process similar to that used for any other vegetable oil (see Video 1 and Howstuffworks.com). 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, and 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 (see Figure 1), 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

If you could extract that oil cost effectively, you would have the raw material to make fuel for cars, trucks, trains, and planes. The U.S. Department of Energy's Pacific Northwest National Laboratory found that 17 percent of the United States' imported oil for transportation could be replaced with homegrown, algae-based biofuels. However, there are still considerable challenges. In particular it is not clear yet what the ultimate cost per gallon of fuel will be. In 2007 a start-up biotech company, Joule Unlimited, stated that its product could supply all of the transportation fuel for the United States from an area the size of the Texas panhandle and built a demonstration plant in New Mexico (see Figure 2 and Video 2). They claimed they could produce oil that would be cost competitive with crude oil at $50 a barrel. However, the company shut the plant down in 2017 after management was unable to raise money for further development. In addition, a 2023 study from The International Journal of Life Cycle Assessment has shown that when infrastructure and electricity use are included, algae-derived biofuels are not yet favorable over petroleum-derived fuels.

Note: also see OWOE Cool Tech - Artificial Photosynthesis

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