TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The system further comprises: a processor for processing the useful material to produce energy, where the processor comprises at least one of an incinerator, a gasifier and a bio-digestor; at least one treater for treating the useful material to adjust a fuel performance property of the useful material prior to processing, where the treater adds at least one of a high energetic material and a low energetic material to the useful material; and at least one controller for controlling operation of at least one of the system, detector, separator, treater and processor.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method (M1) a value range requirement of effective atomic number (Z(eff)) and density is selected to provide a useful material having a relatively high Gibbs free energy, Helmholtz free energy, higher heating value or lower heating value to carbon by weight ratio. The method (M1) further comprises: processing the useful material to produce energy, where the processing step comprises at least one of incineration, gasification and bio-digestion; prior to processing, treating the useful material to adjust a fuel performance property of the useful material, where the treating step comprises at least one of adding a high energetic material and low energetic material to the useful material, where the low energetic material is added when a ratio of Z(eff) to density of the useful material is greater than or equal to a first value but less than a second value, and the high energetic material is added when a ratio of Z(eff) to density of the useful material is greater than or equal to a second value; treating the residue based on a parameter of the residue measured by the detector, where the parameter comprises at least one of Z(eff) and density; and comparing the high energy x-ray (H) and low energy x-ray (L) results against salt and glucose to determine the desirability of a material, where the degree to which each pixel in an image is similar to the (H, L) vector for sugar represents the degree to which the material represented by the pixel corresponds to a collection of organic materials, and the degree to which each pixel in an image is similar to the (H, L) vector for salt represents the degree to which the material represented by the pixel corresponds to a collection of inorganic materials. The treating step comprises: measuring a water content of the useful material; measuring a dual-energy transmissivity of the useful material; calculating an adjusted dual-energy transmissivity by compensating for the measured water content; and adjusting addition of high-energetic material and low-energetic material based on at least in part of it, where the water content is measured using a method including microwave, millimeter-wave, or terahertz technology. Preferred Components: The parameter of interest comprises at least one of Z(eff) and density, where an upper limit for density comprises density of PVCs and an upper limit for Z(eff) is 8. The detector: is adapted to measure at least one of Z(eff) and density of the material stream; and comprises a dual-energy x-ray. The first value comprises a value of a ratio of Z(eff) to density for cholesterol, where the second value comprises a value of a ratio of Z(eff) to density for octane. EXAMPLE - No suitable example given.