The energy potential of municipal biosolids is small. At an average higher heating value of 19 MJ/dry kg (Table 3.3), the energy content of all the primary and treated biosolids produced in 1995 in the United States can be estimated to be 0.163 and 0.113 EJ/year, both of which are much less than the energy potential of MSW. This relationship is a permanent one because of the nature of MSW and biosolids generation. Nevertheless, several combined treatment — energy recovery processes alluded to earlier for extracting energy from biosolids are in commercial use in many wastewater treatment facilities. The recovered energy is generally utilized on site as a captive fuel for the facility.