Emissions from systems that use a catalytic converter are substantially reduced by introducing hydrogen, or a hydrogen containing fluid or fuel component, into the exhaust stream being scrubbed by the catalytic converter, resulting in instant lightoff and a significant reduction in emissions. Hydrogen for injection into the exhaust stream may, optionally, be generated within the vehicle using heat recovered from the catalytic converter, and / or the engine or elsewhere in the exhaust system, by a thermoelectric generator, the electrical output of which may be used to perform electrolysis and / or to power a reformer in order to generate the hydrogen. The thermoelectric generator may be retrofit onto the catalytic converter, or integrated in a way that enhances thermoelectric generation, including providing a catalyst coated heat sink and integrated cooling pipes to enhance the thermal differential required for thermoelectric generation. Sensors such as an oxygen sensor and temperature sensor may be provided to assess converter performance and adjust the temperature differential to ensure that the temperature of the converter remains optimum.