Which Indian airport achieved the distinction of becoming the nation's first aviation facility to be powered entirely by solar energy?

The correct option is Cochin International Airport.

Step-by-step Explanation:

1. Historic Achievement: On August 18, 2015, Cochin International Airport Limited (CIAL), situated in Nedumbassery, Kerala, became the world's first fully solar-powered airport.

2. Solar Power Installation: The transition was achieved with the inauguration of a 12 Megawatt peak (MWp) solar plant consisting of over 46,000 solar panels spread across 45 acres. This facility generates approximately 48,000 to 50,000 units of electricity daily, fulfilling all operational requirements of the airport and making it energy neutral.

3. Global Recognition: For its visionary green energy initiative, CIAL was recognized by the United Nations Environment Programme (UNEP) and conferred with the prestigious 'Champions of the Earth' award in 2018 under the Entrepreneurial Vision category.