TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Reactor: The photobioreactor is designed to increase photosynthetic efficiency by providing diffuse light to the photobioreactor chambers. The surface area of the photobioreactor chamber is exposed to light be greater than the surface area of land covered by the photobioreactor. The structural support to the photobioreactor chamber is provided by the water in the water basin, positive buoyancy air pockets in the photobioreactor chambers and/or structural heat weld in the plastic or composite film. The photobioreactor further comprises a low-shear pump (135) to circulate algae and growth medium through the chamber. The photobioreactor further comprises a low- shear filter, growth medium and photosynthetic microorganism in the photobioreactor chamber. The chambers are placed at an angle to each other and affixed at their tops and bottoms to neighboring chambers, to create an accordion shape from a cross-sectional view. The photobioreactor further comprises a perimeter wall surrounding the water basin, a bottom liner below the water basin and a top layer of plastic above the water basin to decrease water loss from the water basin. The water in the water basin provides a thermal mass to decrease fluctuations in temperature of the photobioreactor chambers. The photobioreactor chamber comprises a bottom layer and top layer of plastic film that are joined together, with an air pocket at the top of the chamber to provide positive buoyancy, where the shape of the photobioreactor chamber is maintained by structural tension. The air pocket collects oxygen produced by photosynthesis, where the oxygen enriched air is collected to provide increased efficiency of combustion in a power plant or combustion chamber. The top layer of plastic contains a dye, coating or additive to block the transmission of some or all ultraviolet or infrared light, while allowing transmission of visible light to support photosynthesis. The photobioreactor further comprises one or more sensor ports, each sensor port contains one or more sensors chosen from dissolved carbon dioxide sensor, dissolved oxygen sensor, pH sensor, temperature sensor, turbidity sensor, dissolved solid sensor and fluorometric sensor, where signals from the one or more sensors are fed to central control unit. The central control unit regulates the function of one or more control units to control one or more environmental conditions within the photobioreactor chambers in response to sensor signals. The photobioreactor further comprises secondary bioreactor into which harvested microorganisms can be transferred and subjected to conditions to enhance lipid production. The volume of fluid in the photobioreactor chamber can increase or decrease, when the chamber is inoculated with a new culture. The several species of algae are maintained within the photobioreactor chamber. The pressure within the photobioreactor chambers can be regulated to control the size and shape of the photobioreactor chamber. The air provided to the air tube contains carbon dioxide from source such as atmospheric carbon dioxide, carbon dioxide canister, exhaust gas of power plant or the exhaust gas of combustion chamber. The air tube is provided with gas with an oxygen content between zero and two percent by volume, to remove dissolved oxygen from growth medium in the photobioreactor. The carbon dioxide concentration can be controlled to regulate the pH of growth medium in the photobioreactor chambers. Preferred Method: The photosynthetic microorganisms are algae. The algae are subjected to an environmental stress to increase lipid production, preferably subjected to a combination of two or more different environmental stresses to increase lipid production. The environmental stress is carbon dioxide depletion. The carbon dioxide is not provided to the photobioreactor chambers. The environmental stress is nitrogen depletion. The environmental stress is reduced or increased exposure to light. The method further involves providing diffuse light to the photobioreactor chambers to increase photosynthetic efficiency. The method further involves removing the oxygen enriched gas from the air pockets to improve the efficiency of combustion in a power plant or combustion chamber. The method further involves venting the gas from the air pockets at one end of the closed system photobioreactor, or venting the gas from the air pockets along the length of the closed system photobioreactor to reduce oxygen concentration in the growth medium. The exhaust gas is vented under water. The method further involves regulating the gas pressure in the closed photobioreactor chambers by the depth below the water surface of the exhaust gas vent. The method further involves pumping growth medium through the photobioreactor chambers, where the growth medium leaves the photobioreactor at one end and is pumped to the other end of the photobioreactor to create unidirectional current through the photobioreactor chambers. EXAMPLE - No suitable example given.