Career
He hails from Narvik and went through the ranks of FK Mjølner. The club had a short stint on the first tier, in the 1989 Norwegian First Division (the year before the league received the name Tippeligaen). He was also capped once during his spell at Mjølner.
Later, in 1991, he joined first-tier club Tromsø Illinois. Grenersen played for Tromsø until late 1997, when he retired.
He moved back to Narvik, and has among others served as youth coach and chairman in Mjølner.