The Biodiesel Education Program at the University of Idaho has created a seven-lesson curriculum to help kids ages 8-12 understand the concepts of energy and renewable energy. The renewable energy focus of this curriculum is biodiesel.
The curriculum was written for 4-H clubs, but can easily be used by elementary school teachers as well.
See this link to download the student workbook and instructor’s manual: http://www.uiweb.uidaho.edu/bioenergy/4-H.shtml