What are the disadvantages of using an internal combustion engine?

The thermal efficiency of internal combustion engine is not very high, the power can only meet the general requirements, and it cannot provide great power and continuous output power, because it works in a reciprocating cycle and is mainly used in vehicles and ships. Gas turbines and turbines are generally used in aircraft, aircraft carriers and aerospace. At the same time, the emission requirements of internal combustion engines are getting higher and higher, and the energy saving and emission reduction of internal combustion engines need to be further improved.