Yes, ADEQUACY is a Scrabble word!

Letter values in Scrabble US: A 1, D 2, E 1, Q 10, U 1, A 1, C 3, Y 4.

Is it a valid word?

ADEQUACY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the quality of being able to meet a need satisfactorily: "he questioned the adequacy of the usual sentimental interpretation of the Golden Rule"
the quality of being sufficient for the end in view