An energy recovery unit (8) for use in a vehicle exhaust system (6) comprises an inlet (24) for receiving exhaust gas from the exhaust system (6); an outlet (26) for returning exhaust gas to the exhaust system (6); a thermoelectric generator (20) disposed between the inlet (24) and the outlet (26); and a valve arrangement operable to direct exhaust gas entering the inlet (24) across the thermoelectric generator (20) to enable the thermoelectric generator (20) to generate electrical energy from thermal energy contained in the exhaust gas, wherein the valve arrangement is operable to vary the direction of exhaust gas flow across the thermoelectric generator (20).