Compounds of formulawherein the substituents have the meanings given in claim 1, and agronomically tolerable salts, isomers and enantiomers of those compounds, are suitable for use as herbicides. The tool includes a first tool part including a first abutment and a first electromagnetic coil. The recirculated flue gas source receives a combustion flue gas from an oxygen fired boiler of the power plant, and provides the combustion flue gas to the recirculated flue gas supply line.