Powell smashed in a right foot drive for his 15th goal of the season as Steve Davis' side poured forward in search of a late leveller.
Torquay deservedly took the lead in the 54th minute when left winger Danny Stevens latched on to a cross from left-back Kevin Nicholson.
Stevens picked his spot to beat Crewe goalkeeper Steve Phillips with a measured shot that curled into the far corner. It was Stevens' sixth goal of the season and sparked wave after wave of Torquay attacks.
Nevertheless, Crewe looked dangerous on the counter and when Powell was fouled by Mark Ellis in the 76th minute it seemed as though they would restore parity.
However, home shot-stopper Bobby Olejnik guessed the right way to brilliantly palm away Harry Davis' spot kick, before Powell struck late on.