Answer: Kerala
Notes: Idukki Hydroelectric Project in Kerala completed 50 years and Moolamattom power plant generated 115,852.672 Million Units (MU) in five decades. It is built across Periyar River in Idukki district of Kerala. It is the largest hydroelectric project in Kerala. Moolamattom powerhouse is the longest underground power station in India and has the largest pressure shaft.
