Figure 6 Phoenix transpor tation fuels energy (in PJ). Ver tical flows are indirect energy flows during the feedstock and refining stages of fuel production occurring outside of Phoenix. Horizontal flows show energy contained within the physical fuels. Note that ver tical flows are not added to horizontal flows. Vehicle manufacturing is included as an additional flow in gray on the left-hand side of the figure. PJ = petajoules. to note that some g