Neutralization of enemies with a batarang (the Riddler missions). (Batman: Arkham Knight)

In missions in which you should use the batarang to find the enemy(it highlights red), then find somewhere electricity, to fly there betarangom and after to hit people with the bomb. Can't find electricity in one of those situations. Also can't find on the Internet completing all of these tasks. But 100% this video exists. Help to find.