In 1978, with energy prices rocketing due to the oil crisis, a group of volunteers in Denmark took matters into their own hands and built a wind turbine to power the town's school.
They called it Tvindkraft and its design revolutionised the wind industry.
Rachel Naylor speaks to Britta Jensen, a teacher from the school, who worked on the turbine.
(Photo: Tvindkraft. Credit: Tvindkraft)