The estimated net retort fuel requirements for entrained-solids retorting of 19,200 tons of 30 g.p.t. oil shale with a 5:1, shale:steam, ratio were determined for use with the rapid cost evaluation method. The results have been summarized in table 1, and appear graphically in figure 1. Part II of this discussion shows in some detail the way these values were calculated. It should be stressed that these values represent an estimate only, based on available data, and are subject to change. Substituting petroleum crude oil heat data for crude shale oil, estimating 50 percent boiling points of shale-oil crudes, and obtaining heat data for higher retorting temperatures by extrapolation of lower temperature data, etc., introduce possible errors. However, in spite of these necessary expediencies, the results appear to be reasonable approximations, when compared with actual pilot plant fuel consumption data. The entrained-solids retort was designed to produce oil at various retorting temperatures. Heat recovery and minimum heat loss to the surroundings were not considered critical.