NOVELTY - The trough filter has filter elements (1010,1020) which are configured to form troughs. An annular exhaust gas outlet or an inlet channel is formed between the filter modules. A thermoelectric generator (1040) is positioned in an exhaust gas outlet or an inlet channel. A heat exchanger (1050) is connected to the second support structure. A thermoelectric module (1070) is positioned between the heat exchangers. A heat exchanger (1060) is connected to the third support structure. Another thermoelectric module is positioned between the heat exchangers.    USE - Trough filter such as diesel particulate filter (DPF) or gas particulate filter (GPF) or substrate such as integrated with thermoelectric generator in exhaust system of vehicle (claimed).    ADVANTAGE - The temperature gradients across the substrate or filter can be reduced and the durability can be enhanced by locating thermoelectric generation elements and/or coolant flow in the hottest region of the substrate. The operation window of the after-treatment system can be widened. The heat transport in the radial direction which facilitates the use of low thermal conductivity, high porosity oxide ceramic materials can be improved. The thin wall configurations in devices capable of efficient heat extraction from exhaust gas can be achieved. The heat extraction is enhanced at homogeneous radial temperature and thus allows more efficient waste heat recovery within the vehicle. The concentration of various pollutants within the exhaust gas can be eliminated. The overall thermal conductivity, vehicle's fuel consumption and carbon-di-oxide emission can be minimized.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a vehicle comprising internal combustion engine; and    (2) a method for converting heat into energy.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross section of the trough filter including integrated thermoelectric generator.    Filter elements (1010,1020)    Inner diameter (1021)    Thermoelectric generator (1040)    Heat exchangers (1050,1060)    Thermoelectric module (1070)