Management Resources in the 21st Century

The emerging paradigms are being driven by a growing awareness of the need for initiatives to address climate change, reduce greenhouse gasses, divert waste from landfills, derive beneficial uses from solid waste, improve municipal energy efficiency, and develop renewable energy projects, in particular, renewable energy derived from municipal wastes. Faced with an aging but rapidly expanding infrastructure, as well as the mandate to efficiently manage their assets, municipal governments are caught in the perplexing situation of becoming more efficient while working under the pressure of smaller budgets, fewer resources, and less staff. One response to these new paradigms may be the development of eco-parks or eco-campuses in the evolution of the integrated solid waste management (ISWM) system.

The inclusion of modern waste-to-energy (WTE) within the eco-campus could be the catalyst for additional synergistic recycling industries as a source of lower-cost electricity for the campus. Integrating these various municipal services, recycling processes, and green energy production into a single campus will result in a more robust, flexible, and efficient resource management system. Daily and seasonal peaks and valleys in the delivery of solid waste materials and composition may be efficiently managed with a versatile and robust ISWM system.

Future industries and processes for integration into the eco-campus may include many of the “emerging and alternate” solid waste conversion technologies, many of which are the bailiwick of the discipline of chemical engineering. These new and innovative processes include foodwaste composting, biosolids conversion, biofuels, anaerobic digestion/co-digestion, depolymerization, gasification, pyrolysis, torrification, and vitrification. A wide range of solid, liquid, and gaseous fuels can be produced from the above-noted emerging technologies, which may offer higher revenues than from the traditional sale of electricity to the local electric grid, potentially reducing the overall solid waste and recycling costs to the local system rate payers.

Mass-burn municipal waste combustion facilities are currently the workhorse of the US WTE industry. Over the past 20 years, the WTE industry has made significant improvements in the reduction of air emissions and water and reagent consumption, along with greater efficiency due to higher boiler and turbine-generator availability, gross and net electrical energy production, and the recovery of ferrous and nonferrous metals. Recent advancements in metal recovery from WTE ash residue now include ferrous and nonferrous fines (materials less than three-eighths of an inch). A byproduct of the advancements in metal recovery are a family of sized aggregates produced from bottom ash, which may potentially be recycled as construction aggregates or as a feedstock for production of Portland cement, one of the major building blocks of the industrial era. As serendipity would have it, these advancements in metal recovery and engineered aggregates will also help solid waste managers advance on the goal of zero waste.

Looking to the future, there may be options to expand the current range of services provided by traditional WTE facilities with the addition of some of the above-noted emerging and alternate technologies. Integrating these new technologies with WTE, side by side or located within the eco-campus, may open up many new opportunities to increase energy production, while also beneficially recycling the residuals from these new processes, thereby minimizing the final disposal of bypassed waste and residuals to the landfill.

Future locations for the development of eco-campus may include any of the following:

• Landfill sites
• Waste-to-energy facilities
• Wastewater treatment facilities
• Former brownfield sites
• Fossil power plants
• Industrial refineries
• Greenfield sites

Eco-Campus
The emergence of an eco-campus may be the ultimate end for sustainable resource management and the beginning of a new paradigm: waste management morphs into resource management. Integrating solid waste management technologies into a single campus offers significant synergies and benefits. It is also conceivable that traditional renewable energy facilities, such as solar, wind, and geothermal, could likewise be located at these “resource centers.”

A fully integrated municipal ecological resource campus would contain all of the elements of the integrated solid waste management, from the lowest rung (landfills and ash fills) to the remaining higher-rung technologies (compost, anaerobic and aerobic digestion, waste-to-energy, and material recovery facilities), and many of the emerging waste-to-biofuel conversion technologies if they are compatible with the local energy markets. With the eventual development of “distributed” bio refineries for production of renewable energy and fuels from local wastes, additional economic development and high-quality careers and jobs could be added to the campus to take advantage of local energy crops and agricultural wastes.

Figure 1. illustrates a future eco-campus that integrates many of the elements of the integrated solid waste management system, along with many of the emerging waste conversion technologies.

Material Recovery Facilities of the Future
An integrated system employing a variety of solid waste conversion technologies can provide a robust yet flexible system to meet seasonal variations and also take advantage of local market conditions. The era of green energy produced from municipal solid waste (MSW) is just beginning, and, like landfills and WTE plants before, these facilities will require an assured flow of tonnage for consistent operations and profitability. However, unlike landfills and existing WTE plants, these newer forms of waste conversion facilities can be more sensitive to the makeup of the feedstock, both in composition and physical characteristics. How does this affect the material recovery facility (MRF) of tomorrow?

Certain materials will need to be included or removed, sized properly (i.e., screened or shredded), dried, or densified per the requirements of the selected green energy technology. The future MRF will be required to function as both a materials recovery and fuels processing facility, similar to previous refuse-derived fuel (RDF) plants. In the past, RDF plants focused primarily on fuel preparation at the expense of recycling. Ideally, both of these functions can be accomplished, with only minor processing changes on a day-to-day basis, to seamlessly convert back and forth from recovered materials to renewable fuels/energy, based on the best revenue stream on a given day (or even hour) with electric rates.

In the future, as green energy technologies evolve, the MRF as we know it could actually become extinct. This could lead to significant collection cost savings via a single-bin curbside collection of all MSW (including greenwaste, household hazardous waste, pharmaceuticals, and e-waste). Processing at the MRF of the future could easily adjust the output of the system as desired, for heat, electricity, syngas, propane, methane, ethanol, biodiesel production, or for recycling of bulk material commodities.

Locating the MRF and future waste conversion facilities either on the same site or even within one building has significant advantages. For example, the area under the tipping floor of a modern waste-to-energy is often a mound of compacted fill to rise up the elevations of the tipping floor to allow wastes to be discharged into the refuse pit. This area could be constructed as a basement under the tipping floor for the addition of a MRF to allow processing of recyclable materials, or the MRF could be located adjacent to the tipping building. In this way, the MRF can enjoy lower costs and greater benefits due to shared infrastructure, staff, tools, and equipment with the WTE facility.

Management Options
The overall management of the eco-campus will likely remain the responsibility of the sponsoring solid waste management agency. The proven track record of the public-private partnership (PPP) as a vital provider of services within the integrated solid waste management industry will likely continue. Private ownership, operation, and maintenance of the various waste conversion technologies will most likely be the model due to the overall risks associated with emerging and alternate waste conversion technologies.

As the program manager, the sponsoring integrated solid waste management agency will help with day-to-day and long-range decision making amongst the various eco-campus tenants to manage the necessary flow of materials for the successful operation of each process. Waste diversions, transfers, and adjustments in feedstock requirements will be necessary due to process availability and maintenance schedules, daily, weekly, and seasonal waste generation, compositional fluctuation, and ongoing process improvements. Local, state, regional, and global market conditions will likely affect the overall program management of the eco-campus.

Eco-Campus Savings
There are several opportunities for the overall integrated solid waste management system and eco-campus tenants to realize significant savings and operational efficiencies. These include internal use of renewable energy, shared use of staff, resources, infrastructure, equipment, and tools.

Internal Use of Renewable Energy
The shared electrical savings which may result from the internal use of electricity on the eco-campus warrants a serious evaluation of the various options suitable for each community and the processes which are to be included on the campus. The potential cost savings that can be realized by the internal use of renewable energy produced from modern WTE facilities may be in the range of a 3 to 6 cents per kilowatt-hour spread. Typically, power purchase agreements are negotiated with the local electrical service provider on a long-term basis (10-20 years). Representative values of municipal WTE projects selling their electricity to the local utility currently range between 4.5 to 8 cents per kilowatt-hour. The cost of electricity that municipalities pay on an industrial rate can be in the range of 6 to 12 cents per kilowatt-hour. A 3-cents-per-kilowatt-hour spread is conservative, and in some parts of the US the spread may be as high as 6 cents per kilowatt-hour, depending upon the local regulations affecting the purchase and sale of electricity by regulated electric utilities.

The cost differential between the price at which electricity is sold and purchased can be shared internally between the agencies operating on the eco-campus for the shared benefit of the solid waste system rate payers, and more importantly, the advanced waste conversion processes that are attracted to the eco-campus. Depending upon the amount of electricity generated, the shared cost savings potential is significant, ranging from millions to tens of millions of dollars annually.

In a similar fashion, energy in the form of steam and heat, utilities (hot water, chilled water, compressed air, and synthesis gas) can also be generated by waste conversion technologies and sold within the eco-campus. These utilities are not regulated as tightly as the bulk electric system and may provide even greater shared revenues to the ISWM system on the eco-campus.

Shared Use of Staff
Staffing of the eco-campus will include management, administrative, engineering and technical, operation, and maintenance staff. These skilled positions can be shared internally within the eco-campus under various contractual arrangements between the sponsoring agency and waste conversion tenants. The advantage of this synergistic sharing is that most of the staff will be familiar with the environmental and technical issues associated with MSW and the conversion of these wastes into recyclable commodities and/or energy.

Many of the processes on the eco-campus will require around-the-clock staffing that can assist with planned and unplanned maintenance activities or responses to local abnormal or emergency situations. Alternatively, many of the processes on the eco-campus are not full-time or continuous. This allows these functions to be served by campus staff on an as-needed basis, without the burden of constant planning and coordination for subcontracted services.

Shared Use of Resources
There are a host of resources and infrastructure associated with the eco-campus that can be shared by the various tenants. This includes civil site features (perimeter fencing, security, landscaping and buffer from adjoining developments, access roads, stormwater quality and quantity measures, and yard and facility lighting); weigh scales, fuel depot, and water utilities (potable, process, sanitary, and wastewater). The overall cost of operation and maintenance of these resources would be managed by the sponsoring solid waste agency and equitably distributed to the various tenants on the campus.

Shared Use of Equipment
A wide range of heavy equipment and tools is typically required for the delivery, transfer, processing, and disposal of wastes. These include mobile equipment such as pickup, dump, and transfer trucks, and earthmoving equipment such as dozers, road graders, excavators, and front-end loaders. Other specialized equipment employed for size reduction of waste materials includes shredders, chippers, grinders, screens, trommels, and other specialized equipment. The number of these pieces of equipment can be minimized under proper shared use agreements. Additionally, a more cost-effective life cycle can be realized by the progressive use of this equipment. For example, dozers and front-end loaders can be used in more demanding and aggressive applications for the disposal of ash and other process residuals on the landfill after being used in less aggressive applications in the early part of the equipment’s life. In this way, the life cycle cost of equipment is optimized while providing the opportunity for many pieces of equipment to be rebuilt and recycled for improved cost-effectiveness.