Getting greener

To meet upcoming fuel economy and emissions regulations, the developmental homogeneous charge compression ignition (HCCI) engine shows promise, but pursuit of more conventional engine technologies may be the better path.

One of the biggest challenges for the global auto industry today is the ever-rising demand for better fuel economy and emissions. Be it the Corporate Average Fuel Economy (CAFE) target of 54.5 mpg by 2025 in the U.S. or the 95 g/km target for CO₂ emissions by the year 2020 in Europe, the major automotive markets are facing intense pressure to meet these targets. Successfully achieving these efficiency and emissions goals, along with keeping pace with the natural trajectory in performance improvements, would require nothing short of giant leaps on the technological front.

One such technology, which has been on the hot seat this decade and earlier, is the homogeneous charge compression ignition (HCCI) engine. This prototype engine technology aims to have the best of the conventional engines of today-the low emissions of a petrol engine and low consumption of a diesel engine. The petrol engine employs homogeneous charge spark ignition (HCSI) as the uniform combustion mixture is ignited by a spark plug; while the diesel has stratified charge compression ignition (SCCI) as the fuel is directly injected into the chamber and combustion occurs at the air-fuel boundary of the tiny droplets of the stratified charge.