Process Engineered Fuels. PEF, (some known as pellet fuels), are produced from a mixture of industrial and/or commercial plastic scrap and other industrial and/or commercial scrap materials and/or from plastic and other materials diverted from the waste stream, along with binding agents and Additives. The proportions of the major plastic and other components can be varied to yield a pellet fuel possessing the desired combustion characteristics. PEF is designed to provide a highly predictable and uniform Btu content, burn rate and flame temperature, and PEF of a particular composition will yield ash with known characteristics. (Comments of the American Plastics Council on Proposed Revisions to Title V Operating Permit Regulations, submitted to the U.S. EPA, October 30, 1995).