NOVELTY - The system (100) has a planar thermoelectric generator (TEG) (110) including thermoelectric (TE) elements (116) in thermal communication with a cold-side heat exchanger (112) and a hot-side heat exchanger (114). The cold-side heat exchanger transfers heat (130) to combustible fluid (122) i.e. crude oil, where the combustible fluid is filled in a container (120) e.g. fuel reservoir and pipeline (124). TEG stations are distributed along the pipeline. The cold-side heat exchanger includes an energy transmission element in thermal communication with the combustible fluid.    USE - TE power generation system for oil or gas pipelines or reservoirs.    ADVANTAGE - The system allows TEG stations to produce electricity for operating control and monitoring systems, providing cathodic protection of pipeline, operating small pumps and valves, and maintaining elevated fluid temperature to reduce pumping losses. The system achieves TEG efficiency improvements by using waste heat from the TEG to preheat the fuel and air used in an integrated burner. The system can improve combustion efficiency, and reduce the amount of the fluid used in combustion by the burner and greenhouse gas emissions. The system allows active cooling or cooling by the fluid to lower the cold-side temperature and to improve the TEG conversion efficiency, so that the active cooling of the TEG can realize compact, more efficient and higher power density TEG systems. The system can avoid use of a stand-alone recuperator, thus improving the system-level power density and efficiency by reducing the mass and parasitic power due to an additional pressure drop through the recuperator. The system allows the integrated recuperator to perform preheating of the air and/or fuel without additional weight or pressure drop. The system uses heating of the process fluids to improve separation of gases and liquids or to improve separation of liquids with different densities. The system reduces the amount of energy used to transport fluids in pipelines by reducing the viscosity of the transported fluid. The system warms the oils to improve the energy efficiency of the transmission system by reducing friction losses. The energy transmission element avoids pumping of a cold-side working fluid through the cold-side heat exchanger, and can increase system-level efficiency.    DETAILED DESCRIPTION - The energy transmission element is a heat pipe or thermosyphon. INDEPENDENT CLAIMS are also included for the following:    (1) a method for generating electricity by combusting combustible fluid    (2) a method for heating combustible fluid.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a TE power generation system.    TE power generation system (100)    TEG (110)    Cold-side heat exchanger (112)    Hot-side heat exchanger (114)    TE Elements (116)    Container (120)    Combustible fluid (122)    Pipeline (124)    Heat (130)