I think the correct answer would be combustion. The technology that is used in dealing with yard waste to energy would be combustion. Among the choices, it is the only process which involves the release of heat which could be used eventually for other processes.
In this technology, the wastes from the yard are burned as fuel to release heat. The heat in turn is used to boil water and form steam. Steam is made to reach high pressures and turn the blades in a turbine generator in order to yield electricity. The technology is fitted with an air pollution control devise which eliminate pollutant gases from the combustion chamber to prevent pollution.
