NOVELTY - A method (M1) for generation of power or fuel using processing that produces exhaust gas stream laden with carbon dioxide, involves: using at least carbon dioxide to generate biomass and gaseous byproduct including oxygen; collecting gaseous byproduct; and combusting a fuel in presence of the oxygen from the gaseous byproduct.    USE - For generating of power, fuel, energy and for performing coal liquefaction (claimed).    ADVANTAGE - The method of facilitates the low cost, environmentally friendly generation of power or fuel. Extra processing is avoided by forming a closed loop system and simply returning the output gas from the creation of biomass. Since gaseous byproduct includes a substantial amount of oxygen, it can be used in furtherance of the power generation process, such as through the combustion of fossil fuels or biomass. The output gases created during the process of forming the biomass are collected and returned for use in power generation, possibly without costly processing or being released directly to the atmosphere. The closed loop thus created not only reduces the cost of producing power, but also actually may lead to an increased profit through the use of the resulting biomass to form other beneficial products or as fuel.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for following:    (1) a method (m1) for use during generation of power, involving combusting a fuel in presence of oxygen to create exhaust gas including carbon dioxide, collecting the exhaust gas, using the carbon dioxide from the collected exhaust gas to generate oxygen and biomass, and collecting the oxygen generated;    (2) a method (m2) for use during production of power, involving photosynthesizing a biological agent in the presence of carbon dioxide to generate oxygen and biomass, and collecting the oxygen resulting from photosynthesis and inputting oxygen to a power generator;    (3) a method (m3) for performing coal liquefaction involving converting coal to liquid fuel to produce exhaust gas stream laden with carbon dioxide and using carbon dioxide to generate biomass and gaseous byproduct including oxygen;    (4) closed-loop system (S1) for producing power using photosynthesis comprising power generator including inputs for fuel and gas including oxygen and exhaust gas output, at least one bioreactor for receiving exhaust gas output and for creating oxygen and biomass, and delivery line for transporting at least portion of the oxygen from the bioreactor to gas input of the power generator;    (5) closed-loop system (S2) for producing fuel using photosynthesis comprising unit for converting coal to liquid fuel and exhaust gas including carbon dioxide, and bioreactor for receiving exhaust gas and creating oxygen and biomass using photosynthesis;    (6) a method (m4) of generating energy involving combusting coal in presence of pure oxygen to produce carbon dioxide, generating biomass and gaseous byproduct including oxygen from the carbon dioxide, collecting the gaseous byproduct, and combusting coal using the oxygen in the collected gaseous byproduct.