Systems and methods are provided for growing algae and/or other microorganisms in a controlled environment while reducing or minimizing the amount of energy required for maintaining desired conditions in the growth medium. The systems can be based on a photobioreactor having a “tube-in-tube structure”, where an outer cylindrical tube contains a heat regulation fluid that surrounds one or more inner cylinders that contain microorganisms in growth media. The heat regulation fluid in the outer cylinder, as well as the outer cylinder itself, can assist with regulating the temperature of the growth media in the inner cylinder(s).
