Japan\'s largest mobile phone operator, NTT DoCoMo, plans to start powering its cellphone tower network with renewable energy such as solar, wind or biomass, the company said Friday. The move could one day allow the company to feed excess electricity back into the grid, and would also act as a safeguard during power grid outages caused by natural disasters such as the March 11 quake and tsunami. NTT DoCoMo, which has 90,000 cellphone relay stations, will start the project by building some 10 renewable energy facilities in fiscal year 2012 to supplement the conventional electricity supply, media reports said. Daisuke Sakuma, a spokesman at NTT DoCoMo, told AFP that \"we are planning \'green transmission stations,\' which would be run on eco-energy such as bio-fuel cells, wind or solar power.\" \"We have not decided details yet, including how many stations would be operated that way,\" he said, adding that the company could one day sell excess energy, although for now its aim was to meet its own power needs. Sakuma said the move could also help protect the system against widespread blackouts. The March 11 seismic disaster knocked out power lines and mobile phone transmissions in large parts of the Japanese northeast. \"In the wake of a major earthquake, a power outage of many hours would disrupt our service... Our plan is also meant to be an anti-quake measure, in addition to the environmental concerns.\"