Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
3.0 Renewable Energy Technology
Options
Applications
RDF is preferred in many refuse to energy applications because it can be
combusted with technology traditionally used for coal. Spreader stoker fired boilers,
suspension fired boilers, fluidized bed boilers, and cyclone furnace units have all been
utilized to generate steam from RDF. Fluidized bed combustors are often preferred for
RDF energy applications due to their high combustion efficiency, capability to handle
RDF with minimal processing, and inherent ability to effectively reduce nitrous oxide
and sulfur dioxide emissions. In all MSW or RDF boiler types, the boiler tube metal
temperature must be kept at a temperature less than 800ºF to minimize boiler tube
degradation due to chlorine compounds in the flue gas.
There are 15 operating refuse derived fuel plants in the United States with an
annual capacity to process 6.2 million tons of waste. Typical RDF facilities process 500
to 2,000 tons of RDF per day (the average amount produced by 200,000 to 800,000
residents). The average design capacity of RDF plants operating in the US is about 1,330
tons per day of waste. 31
Cost and Performance Characteristics
Table 3-14 has typical ranges for performance and costs for a 300 ton per day
RDF facility.
Environmental Impacts
RDF faces the same environmental opposition as MSW while providing the same
environmental benefits. RDF plants are generally viewed as being more compatible with
recycling efforts. RDF plants using fluidized bed technology can potentially achieve
lower emissions than mass burn plants.
Kauai Outlook
Like MSW mass burn, RDF is a potentially promising option for Kauai.
Resource availability and developable potential is essentially the same as was previously
discussed in the MSW mass burn section. RDF technology is commercial technology,
but has not been used in as many applications due to its higher cost. The technology does
allow for greater recovery of recyclable materials and the potential for lower emissions.
Finally, an RDF plant could readily burn other biomass fuels, especially if it was based
on fluidized bed combustion technology.
31 Integrated Waste Services Association, 2004.
21 March 2005 3-37 Black & Veatch