Yes, JOULE is a Scrabble word!

Letter values in Scrabble US: J 8, O 1, U 1, L 1, E 1.

Is it a valid word?

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

a unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second
English physicist who established the mechanical theory of heat and discovered the first law of thermodynamics (1818-1889)

Also: j, watt second, james prescott joule.