NTPC Limited on Thursday signed a long-term fuel supply agreement with Singareni Collieries Company Limited (SCCL) for supply of coal to NTPC Ramagundam Super Thermal Power Station for 20 years. NTPC regional executive director Amabrish Dave and SCCL chief general manager Suresh signed the agreement, which is for supply of 10.02 tonne coal per annum to the existing Stage I and Stage II units, according to a release.