Power generation in the country plunged  to 2,390.20 megawatts on Monday as the number of idle power plants rose  from seven to 15, according to the latest data from the Federal Ministry  of Power, Works and Housing.     Total electricity generation has been hovering below 4,000MW in recent months and stood at 3,741.30MW as of 6am on Sunday.       The nation generates most of its  electricity from gas-fired power plants, while output from hydropower  plants makes up about 30 per cent of the total.    But the three hydropower plants  accounted for more than 50 per cent of the electricity generated as of  6am on Monday, with Kainji, Jebba and Shiroro producing 366MW, 354MW and  494MW, respectively.   Egbin, the biggest power station in the country, saw its output drop to 176MW on Monday from 306MW on Saturday.   The idle plants are Sapele, Afam IV  & V, Geregu, Omotosho, Geregu NIPP, Alaoji, Omotosho NIPP, Odukpani  NIPP, Ihovbor NIPP, Gbarain NIPP, Okpai, Afam VI, AES, ASCO and ...