New Delhi: NTPC on Tuesday said it has signed a non-binding MoU with Numaligarh Refinery Read by: एनटीपीसी NTPC Limited (NRL), a subsidiary of Oil India engaged in the business of refining and marketing of petroleum products, for partnership opportunities in the proposed bamboo-based bio-refinery at NTPC Bongaigaon in Assam and other green projects.