Spark-ignition and compression-ignition piston engines are currently undergoing intense examination as energy conversion devices. Much of this attention has been focused on the contribution of these conventional engines to the air pollution problem.
Exhaust emissions will be a major consideration in the design and selection of engines for the future. However, it is believed that evolutionary changes in the conventional piston engines will overcome the exhaust emission problem during the next decade. Changes in the types of engines used for the various applications may occur; if other energy conversion devices prove to be superior for a given application and are economically justified, they will break into the market presently held by our conventional engines.
This paper discusses alternate powerplants we believe will be important in the next decade. It includes brief discussions of such energy conversion devices as rotary combustion engines, gas turbines, stratified-charge engines, compound engines, fuel cells, and batteries.
The challenges facing the spark-ignition and compression-ignition engines are covered in detail, along with estimates of possible changes in engine design or of shifts in the use of types of engines for various applications. The effects that such changes will have on fuel and lubricant requirements are explored.