Using blends of vegetable oils with petroleum derivatives for heating purposes has several advantages over other energy applications for vegetable oils. These advantages are presented in this paper. using the results obtained from the installation of conventional heat generation using diesel and sunflower oil mixtures and the possibilities this holds for Castilla y Leon. Castilla y Leon is the biggest region of Spain: its main activity is the agriculture, with a continental climate. (C) 2004 Elsevier Ltd. All rights reserved.