Power shortages at their SEZs has led realty firms to tap the expertise of power major NTPC to set up captive power plants. Sources in Ansal, Unitech and Parsvnath say that they have signed an MOU with NTPC for captive gas-based power projects of up to 50 MW. NTPC may source gas from Gail. The SEZs would be in Greater Noida, Indore, Dehradun and Gurgaon.