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A gas turbine-driven generator set is being developed as a range extender for a major automobile manufacturer's hybrid electric vehicle. The 24 kW continuous rating is sufficient to propel the automobile at maximum legal speed in the United States. For hill climbing and passing, 30 kW is available. A circumferential recuperator increases efficiency to 30% on unleaded gasoline. There is no gearbox since the permanent magnet generator is mounted on the gas turbine shaft. There is no lubrication system as the rotor group shaft runs on air bearings. The complete generator set with recuperator weighs 36 kg (80 lb). The OEM price will be under $1,000 in automotive quantities. Production units will have catalytic combustion to reduce emissions to less than those of an electric utility power plant. California regulatory authorities have indicated that this could permit a hybrid vehicle to be classed as “zero emission”.

Recuperated intercooled gas turbine cycles offer efficiencies in the 40% and higher range at medium to high loads. Although these cycles offer better low-load efficiency than other gas turbine cycles, the idle and low-load fuel consumption are still not good enough for satisfactory vehicle operation. In addition, response time to sudden demands for power is slow. The multi-pressure gas turbine allows the combustion air to enter the cycle at a different point, reducing the mass flow and the rating of the gas turbine for efficient operation at low power. Yet, the full power of the gas turbine is available quickly for acceleration or hill climbing.