Algae naturally produce oil. When it’s processed, that oil can be turned into biofuel, an alternative energy source. There's just one snag - harvesting the oil from algae-filled water is prohibitively expensive. But researchers have come up with an effervescent solution: bubbles smaller than the width of a human hair can help reduce the costs of collecting algae oil. So-called microbubbles are already used for water purification - they surround contaminants and float them out of the liquid. Similarly, in water containing algae, bubbles can float the algae to the surface for easy collection and processing. The research builds on previous work that used microbubbles to grow algae more densely and thus increase production. This time, however, the researchers produced the fizziness with a new method that uses far less energy, and is cheaper to install. The study is in the journal Biotechnology and Bioengineering. Although microbubbles improve algae harvesting in the lab, they still have to work at larger scales. The researchers are planning a pilot program for an algae biofuel plant, in the hope of making really green energy.