He was a scientific research worker at the psychological laboratory of the University of California at Berkeley in the United States from 1960 up to 1961.
In 1972 Dr. Kremers became a member of the Wetenschappelijke Raad voor het Regeringsbeleid, an independent think tank for the Dutch government.
Unemployment within the province was extremely high, because many miners had been dismissed, but also because of the deteriorating (inter)national economic situation.
As Queen's Commissioner Dr. Kremers conducted an active economic policy to reduce the effects of the mine closures and to push back unemployment.
After his resignation as Queen's Commissioner Dr. Kremers became vice-chairman of the Robeco Group, a Dutch portfolio company.