Would you use pond scum to power your car? Well, that may be a reality in the near future – algae just might be the “fuel of tomorrow” for many reasons. For example, algae grows quickly and produces 60 times more oil than land-based plants. Scientists are discovering ways to turn the energy-filled oil created by algae into a sustainable, carbon-neutral biodiesel. Check out the three main steps to making biodiesel from algae below.
Growth and Processing
Algae is grown in large circular ponds called raceways. A paddlewheel keeps the algae from settling to the bottom of the raceway. This allows a larger amount of algae to convert sunlight into energy. The algae water, known as algal broth, is collected and the algae is separated, dried, and prepared for processing.
There are three methods to extract oil from algae. Expression is an extraction method that simply squeezes the oil out of the algae, a process that is very similar to pressing oil out of olives. Another way to extract the oil is a mechanical extraction called the ultrasonic method. Algae is mixed in a solvent that is then exposed to high frequency (ultrasonic) sound waves. The algae’s cell walls break open and the oil is released. Chemicals can also be used to break down cell walls to extract the algae’s oil. The extracted oil is now “green crude” and must be refined in order to be used as fuel.
Green crude is refined through a process called transesterification. Alcohol and a chemical catalyst are added to the crude to produce a mixture of biodiesel and glycerol. The mixture is then spun inside of a centrifuge to separate the glycerol from the mixture so that the biodiesel can be collected.
Currently, the process for making biodiesel from algae is expensive, which limits the ability to mass produce the biofuel. But investor interest in algae-based biodiesel is on the rise, as scientists continue to find more cost effective production methods. So, this truly green biofuel might be served at your gas station very soon!