A system for producing a hydrocarbon-producing photosynthetic organism. The system comprises a substantially closed conduit system enclosing a fluid, a fluid-moving mechanism adapted to move the fluid through at least a portion of the conduit system, and a harvester adapted to remove at least a portion of the hydrocarbon-producing photosynthetic organisms from the fluid. The fluid contains a population of a hydrocarbon-producing photosynthetic organism and the conduit system configured to permit at least a portion of the population to receive light suitable for photosynthesis.