The system and methods described allow for reduce emissions by using a recirculation device within an engine that connects an air feed line to an exhaust line while cooling the exhaust-gas to form a condensate for further cooling the engine system. In one particular example, a cooling unit is described that cools the exhaust-gas stream flowing there through and collects a condensate out of the exhaust-gas stream for injection back into the air feed line via an injecting device. In this way, an injection of water may be made to reduce NOx emissions during vehicle operations, and the outlay for storage of water on board the vehicle may be eliminated.