A method for utilizing gas produced from an in situ conversion process includes heating an organic-rich rock formation, for example an oil shale formation. The method may include producing a production fluid from the organic-rich rock formation where the production fluid has been at least partially generated as a result of pyrolysis of formation hydrocarbons located in the organic-rich rock formation. The method may include obtaining a gas stream from the production fluid, where the gas stream comprises combustible hydrocarbon fluids. The method may include separating the gas stream into a first composition gas stream and a second composition gas stream, where the composition of the first composition gas stream is a low BTU gas stream maintained in a substantially constant condition and passing the first composition gas stream through a gas turbine to form a gas turbine exhaust stream, where the gas turbine is connected to an electrical generator.