The Next Generation of Service Agreements for Publicly Owned Waste-to-Energy Facilities: Pinellas County Case Study

This paper discusses one of the key lessons learned from administering the first generation of service agreements for public owners of waste-to-energy (WTE) facilities over the past 22 years and how those experiences were incorporated into a new service agreement for the operation and maintenance of Pinellas County’s 24 year old, 3,000 tpd WTE Facility to better protect the county’s interests. Additionally, a major issue raised by the operating companies during the competitive procurement process for continue operation of the facility is discussed and how that concern was addressed in the new service agreement is also presented. Capitalized words or terms used in this paper are defined within the new service agreement.

Improving the Public Acceptance of WTE: Session 8

This topic is important because of the growing need for us to produce and supply low cost energy for public consumption. Demand has increased exponentially, and in order to reduce dependence on foreign oil, coal, and natural gas we need to utilize waste to its full potential. Three major waste to energy plant expansions are happening now at Olmstead WTE, Minnesota and at Lee and Hillsborough Counties, in Florida. New “Greenfield” construction is planned at Harford, Carroll, and Fredrick Counties, in Maryland.

Experiences With On-Line Explosive De-Slagging at Covanta WTE Facilities

An on-line cleaning technique perfected in Europe, which places low-yield explosive charges in close proximity to tube lane pluggage, and uses pre- and post-cleaning video camera surveillance to document results, has been tested at three WTE facilities in the western U.S. operated by Covanta. Testing indicates several tangible benefits relative to the more traditional off-line blasting, water washing (on-line and off-line), and stick blasting (on-line), including: • substantial elimination of cleaning related downtime between maintenance outages; • longer runtimes with less overall fouling and pluggage related ailments; • reduced off-line cleaning time at the beginning of major outages to the benefit of the outage schedule; • exemplary safety of the on-line cleaning process; • less wear and tear on pressure parts and boiler casings; and, • almost no fugitive dust problems in the boiler house that may occur with off-line blasting. The process starts with an initial video survey of fouling conditions. A water-cooled camera with purge air and temperature monitoring is inserted into the flue gas to record the fouling condition of the boiler. Following the survey, a cleaning plan is developed. Shots consist of low-yield detonating cord encased in thin gage aluminum alloy tubing. The charges are positioned in the gas lanes between tubes while being cooled with a water-air mixture and detonated. Following the cleaning effort, a final camera survey is done to verify the cleaning effectiveness, and to follow up with touch-up cleaning if necessary.

Conversion Technologies: The Challenges for the MARTIN Reverse-Acting Grate System

Thermal treatment of waste differs significantly from the combustion of regular fuels due to the fluctuating and unpredictable composition of the fuel. It is therefore necessary to develop processes with safe process engineering technology that guarantee the treatment of waste in accordance with ecological and economic constraints in addition to complying with international legal requirements. Various important factors have to be considered: not only the reduction of the volume and mass of waste and the destruction and separation of pollutants, but also the efficient energy production (electricity and district heating) and the guaranteed treatment of all waste. In order to comply with strict Japanese regulatory policies, particularly with regard to residue quality and overall output of organic substances, grate technology was modified by means of downstream melting processes that are intensive in terms of maintenance, energy and resulting costs. While vitrification of bottom ash and fly ash does improve quality and provide additional recycling possibilities, it has not proven sustainable. Conversion technologies using separated high-temperature processes make integrated production of granulated slag possible. Large market shares in Japan were gained as a result. However, practical experience in largescale plants has shown serious drawbacks with regard to availability, profitability and process safety. The use of alternative waste conversion technologies failed on the German market due to massive technical problems and considerable financial losses for all those involved.

Odor Monitoring and Mitigation at the Hennepin County Waste to Energy Facility

Hennepin Energy Recovery Center (HERC) is a waste to energy facility owned by Hennepin County and operated by Covanta Energy. HERC has been in operation since 1989. The facility burns 365,000 tons of residential and commercial solid waste per year and generates about 34 mega-watts of electricity that is sold to Xcel Energy. HERC is located on the north side of downtown Minneapolis in the Historic Warehouse District, a neighborhood that is changing from industrial to a more commercial/residential mix with loft conversions and construction of new condominiums. The Minnesota Twins baseball team is also siting a new stadium in the parking lot immediately southeast of the facility. The potential for odors from the tipping floor of the facility affecting the neighborhood has become more of a concern due to the changes in the neighborhood. In March 2004 the County began an odor study. This included developing baseline information on odors from HERC and from the surrounding community by conducting daily odor monitoring at select points on the facility property and throughout the community: • Determining how far odors from HERC migrate into the community. • Quantifying detected odors using a Nasal Ranger. • Determining the factors that contribute to these odors. • Developing a method of controlling these odors. • Continued monitoring to determine the impact of mitigation methods. Odors detected were characterized as garbage odors, garbage-related odors, and neighborhood odors. Baseline data showed that while garbage odors from HERC were mostly undetectable beyond the perimeter of the property, there was room for improvement in decreasing the presence and intensity of these odors. The tipping hall was designed to operate under negative pressure to control odors, however the entrance and exit doors were always open and a negative pressure could not be maintained.

Low-Carbon Solid Waste Systems

As awareness regarding the potential threat of climate change has grown in the US, many local governments and businesses are being asked to consider the climate implications of their actions. In addition, many leaders, including solid waste managers, who are not yet pressured from the outside, consider it prudent to account for their greenhouse gas (GHG) emissions and consider it a proactive measure to assess climate risks and opportunities and to show commitment to progress. Sources of GHG emissions in the solid waste management process include: waste transport vehicles, composting facilities, processing equipment, landfills, and waste-to-energy facilities. Over the past 25 years, the levels of GHG emissions have been reduced through technological advancements in waste-to-energy, environmental regulations such as the Clean Air Act, landfill gas capture and control, and the promotion of recycling and reuse. There are many opportunities for solid waste managers to further reduce their GHG emissions levels, including promotion of waste-to-energy facilities as part of a low-carbon solid waste management plan. Waste-to-energy may also, in the future, offer potential revenue from the sale of renewable energy credits and carbon credits in emerging emissions trading programs.

Doubling the Energy Advantage of Waste-to-Energy: District Heating in the Northeast U.S.

In District Heating (DH), a large number of buildings are heated from a central source by conveying steam or hot water through a network of insulated pipes. Waste-to-Energy (WTE) signifies the controlled combustion of municipal solid wastes to generate electrical and thermal energy in a power plant. Both technologies have been developed simultaneously and are used widely in Europe. In the United States, however, WTE is used principally for the generation of electricity. The advantages of district heating using WTE plants are: overall fuel conservation, by increasing the thermal efficiency of WTE, and overall reduction of carbon dioxide emissions to the atmosphere. The purpose of this study was to examine the current situation of district heating in the U.S. and determine the potential for applying DH to existing WTE plants. A preliminary evaluation was conducted of DH application at two WTE facilities in Connecticut: the Wheelabrator Bridgeport and the Covanta Preston facilities. Using a Canadian methodology, the minimal distribution heating network costs for Bridgeport were estimated at about $24 million dollars for providing heat to a surrounding area of one square mile and the DH revenues at $6.8 million.

PCDDs/PCDFs in MSW Emissions: Pre and Post Mercury Control — A Comparison of Profiles

In recent years since enactment of the NSPS, carbon injection has significantly reduced mercury emissions from MSW units. What is not well known is that carbon injection has also resulted in further unintentional reductions in PCDDs/PCDFs emissions from MSW emissions. These emissions reductions have taken place on a mass basis as well as a TEF weighted basis. The latter have been more pronounced on a percent reduction basis owing to changes in the PCDDs/PCDFs profile directly attributable to preferential adsorption of selected 2,3,7,8-substituted congeners on activated carbon injected in the gas stream for mercury removal. These lower molecular weight congeners are typically present in the gas phase and contribute more significantly to the TEF weighted sum.

Innovating the Recovery and Recycling of Waste-to-Energy Ferrous Metals

Most every one of the approximate 90 operating waste-to-energy facilities in North American have a ferrous metals recovery system to extract these metals from the ash stream before the ash is disposed as a waste. Recovery of this ferrous metal obviously reduces the significant landfill disposal cost and associated ash hauling cost for the facility by reducing the volume of materials being disposed. The volume of the ferrous metals stream typically ranges between 1.0 to 4.0 percent of the incoming waste volume. But for facilities which manage hundreds of thousands of materials per year, this relatively small stream of material in many facilities present such a nuisance that the operators at some plants have a penchant not to bother with it for the tenuous value they have received. The value received has been exposed to extreme variations and uncertainty due from the fragmented scrap metal markets, transportation costs, quality of the recovered product (or lack thereof), cost of recovery, and a number of other constraints and issues, some in the control of the facility operator and some not in the control of the operator. As a result, the attention given to this area is also very variable across facilities, even within the same parent company.

York Resource Recovery Center Metal Spray Success

Early US waste-to-energy plants were constructed using conventional boilers designed for fossil fuels, gas, and oil. Combusting MSW exposed those boilers to high levels of sulfides and chlorides that caused accelerated corrosion problems. MSW fuel required higher amounts of excess air that resulted in high furnace gas velocities and metal erosion. Depending upon the individual design of each boiler, effects of higher upper furnace temperature, flame impingement, and flyash carry over were reported. This paper describes a test conducted to extend the useful metal life of superheater tubes by employing recently developed high velocity continuous combustion (HVCC) metal spray materials.