Alfelt was involved with the major avant-garde art movements in Denmark from the 1930s through the 1950s, working in an abstract idiom of colorful prismatic compositions.

Alfelt was born in Copenhagen to the parents Carl Valdemar Ahlefeldt (1882–1954) and Edith Alexandra Regine Julie Thomsen (1893–1938).

According to her museum website, “the rejection was made on the grounds that she already possessed the necessary painting skills.”[1] In 1933, when Alfelt was 23 years old, she attended the International Folk High School in Elsinore.

Soon after this, Alfelt's painting style shifted to a completely abstract idiom of meditative and colorful prismatic compositions.

She took part in Linien (The Line, 1934-1939), the artists' collective and art journal that was the first conduit of French Surrealism to Denmark.

Alfelt was directly inspired by nature, specifically mountains, which she sought out on her many travels, such as her trip to Lapland 1945 and Japan in 1967.