A stationary reciprocating internal combustion engine (RICE) is any internal combustion engine which uses reciprocating motion to convert heat energy into mechanical work and is not mobile. Stationary reciprocating engines differ from mobile reciprocating engines in that they are not used in road vehicles or nonroad mobile applications such as bulldozers, mowers, cranes, etc. Some engines are less easily categorized, for example, a generator mounted on a pallet or a trailer would not be considered stationary unless it will stay at a single site for at least a full year or full season, for a seasonal source.
There are two basic types of stationary reciprocating engines - spark ignition and compression ignition. Spark ignition engines use a spark (across a spark plug) to ignite a compressed fuel-air mixture. Typical fuels for such engines are gasoline and natural gas. Compression ignition engines compress air to a high pressure, heating the air to the ignition temperature of the fuel, which then is injected. The high compression ratio used for compression ignition engines results in a higher efficiency than is possible with spark ignition engines. Diesel fuel oil is normally used in compression ignition engines, although some are dual-fueled (natural gas is compressed with the combustion air and diesel oil is injected at the top of the compression stroke to initiate combustion).
Several million stationary reciprocating engines are in use throughout the U.S. In general, industry uses these engines to drive process equipment such as compressors, pumps, and other machinery and for standby generator sets.
Manufacturers and owners of stationary reciprocating internal combustion engines (RICE) are affected by federal air pollution regulations promulgated in stages starting in 2004.