Power giant NTPC on Tuesday said its board has approved investment proposals worth about Rs 80,000 crore for thermal projects totalling 6,400 MW. The board of directors has accorded investment approval for Telangana Super Thermal Power Project, Phase-II (3x800 MW) at an appraised current estimated cost of Rs 29,344.85 crore, the company said in an exchange filing. The board also approved the proposal for Gadarwara Super Thermal Power Project, Stage-II (2x800 MW), at an estimated cost of Rs 20,445.69 crore, it said. The board also accorded investment approval for Nabinagar Super Thermal Power Project, Stage II (3x800 MW) at an appraised current estimated cost of Rs 29,947.91 crore. NTPC, under the Ministry of Power, is the country's largest power generation company. The NTPC Group's installed power generation capacity was 76,443 MW as of September 30, up from 73,824 MW a year earlier. The company's installed capacity also increased on a standalone basis to 59,168 MW from 57,838 MW