Background
Grenstad was born in Stockholm, Sweden and became a naval officer in 1980 after graduating from Sjökrigsskolan at Näsby Castle.
Grenstad was born in Stockholm, Sweden and became a naval officer in 1980 after graduating from Sjökrigsskolan at Näsby Castle.
Before that, Grenstad had completed a circumnavigation trip with HSwMS Älvsnabben during 1977/1978.
He is currently the Deputy Chief of Operations of the Swedish Armed Forces. During his career as a naval officer he has held positions as corvette chief and commander of the 3rd Surface Warfare Flotilla (3 Ytstridsflottiljen) in Karlskrona. Grenstad did his staff course at the Militärhögskolan between 1994 and 1996.
From January to April 2005 he was commander of Marinbasen within the Karlskrona naval base.
On 1 July 2005, Grenstad became Inspector of the Navy. He left the post on 24 February 2011 and took a position on 1 April 2011 as head of the Swedish delegation to the Neutral Nations Supervisory Commission (NNSC) in the Korean Demilitarized Zone between the North of Korea and South of Korea.
He left the post in 2013 and served after that as the Deputy Chief of Operations of the Swedish Armed Forces. Grenstad was the inspector of naval academic association Sjöholm.
1980 - Sub-Lieutenant
1983 - Lieutenant
1988 - Lieutenant Commander
1998 - Commander
2002 - Captain
2005 - Rear Admiral (lower half)
2005 - Rear Admiral.
He became a member of the Royal Swedish Society of Naval Sciences in 2000 and a member of the Royal Swedish Academy of War Sciences in 2007.