There is provided a surgical instrument for electrothermal coagulation of tissue, which includes a front cylinder at the distal end of the instrument having a distal tip, an elongate carrier, and two spaced cylindrical or strip-shaped electrodes at or on the carrier which are connectable to an HF-ac voltage source. The method includes receiving initial the data for at least one subject to be measured into an adaptive estimator system. As a result, because the RF power supply is oscillated at a low output when starting discharging, a voltage between the RF electrodes can be prevented from changing transitionally and largely. Also included are the affiliated systems of mutual patronage relation constituted by one or a plurality of the systems and nearby power generating system or systems using coal bed methane or pre-mining gas as fuel.