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Processed Refuse Fuel™

Energy Answers is in the business of developing, owning, and operating facilities that maximize the recovery of resources from waste, including energy and materials. Since its formation, Energy Answers has continually assessed the technological alternatives available for achieving this goal. The predominant technology available for recovering energy (but not materials) from waste at the time Energy Answers was making its initial formative assessment of alternatives was what is commonly referred to as mass burn incineration, the technology that still is used predominantly in waste-to-energy facilities around the world.

Energy Answers’ Processed Refuse Fuel™ technology offers proven commercial-scale projects utilizing integrated or satellite waste-to-fuel processing facilities to supply an energy recovery system, suitable for applications greater than approximately 400 tons per day. Based on the award-winning SEMASS Resource Recovery Facility operating in Rochester, MA since 1989. SEMASS was developed, owned and operated by Energy Answers until it was sold in 1996.

Energy Answers' PRF Technology Comparison Brochure

Our PRF technology has been upgraded through the years to allow lower operating cost, greater automation, smaller footprint, and accommodation of other related new technologies.

Resource Recovery Schematic

Following is a description of a centralized Processed Refuse Fuel™ facility designed to process waste into clean alternative energy.

System Description

The Processed Refuse Fuel™ technology option is based on three primary subsystems:

  • Waste receiving and processing
  • Power production
  • Residuals management

Waste Receiving and Processing

PRF is created by shredding municipal solid waste, commercial waste, and selected industrial wastes, and removing a portion of the ferrous metals from the PRF. A major advantage of shredding waste is that the shredding process virtually eliminates the smell of raw waste and instead produces material with an odor similar to wet leaves. In addition, vermin are not as attracted to the shredded material. For long term storage (months), the PRF can be baled, and even if stored outdoors and exposed to the elements, the material can be recovered for combustion with little change in its combustion characteristics.

PRF technology incorporates certain Energy Answers patented equipment and systems. Fuel preparation is accomplished in 16 hours each day, in support of continuous energy generation.

PRF technology has resulted in the elimination of all of the recognized mass burn technology problems as well as improvements in efficiency and ash quality.

Power Production

RDF Boiler Comparison Our patented power generation technology involves a semi-suspension combustion boiler instead of the more traditional mass-burn combustion boiler. As with other solid fuels, it is recognized that by reducing the fuel particulate size (i.e., pulverized coal, sawdust, etc.), the combustion efficiency is increased and ash residue is decreased. Before the waste is fed into the boiler, it is shredded into small particles, thereby increasing the available surface area for combustion and increasing energy generation and efficiency. Our award-winning technology has been fine-tuned to meet the demands of our customers and in the process we have reduced emissions and increased electricity output significantly.

Residuals Management

Energy Answers' philosophy is to treat ash as a raw material for commercial products, not as a waste material requiring disposal.

Energy Answers' research and development efforts have been at the forefront of effective ash utilization and beneficial reuse. Because of the efficient combustion achieved with Energy Answers' PRF technology, production of ash is minimized, and bottom ash and fly ash can be collected and processed together or separately. The bottom ash is processed with a proprietary technology developed by Energy Answers which recovers ferrous and non-ferrous metals and produces Boiler AggregateTM.

Boiler Aggregate™ has been successfully used as landfill gas vent material, in road pavement, and in the production of concrete blocks. Research and development continues for new beneficial uses of these products from the resource recovery process, toward the ultimate goal of zero disposal.

The Ash Management Program developed by Energy Answers for the SEMASS Resource Recovery Facility received the 1993 Excellence in Environmental Engineering Honor Award. It has since been adapted to other resource recovery technologies to improve recovery rates and help minimize landfill requirements.


"Quality engineering is making a difference in man's quest to correct the insults to the environment of the past and provide for greater harmony with nature tomorrow. We are pleased to have the opportunity to recognize those at the forefront of this struggle."

American Academy of Environmental Engineers