Other Solid Waste Processing Technologies
The above sections described disposal methods used in the northeastern Illinois region. In the section below, we will discuss other processing technologies that have been tried in other parts of the country with various degrees of success. The purpose of reviewing these methods is to assess their applicability to the region and the feasibility of recommending any of these means for future solid waste management.
Combustion with energy recovery
Also referred to as waste-to-energy, is an integrated waste management system in which metal, plastic, paper and glass are recycled while the remaining waste is converted into energy through a combustion process that takes place in a sealed furnace. This achieves a 90% volume reduction which produces ash that is also recyclable into road or cement aggregate (SWANA, 2006). The modern technologies used in such facilities to generate power result in fewer emissions than conventional fuels burned in most American power plants, specifically coal-fired plants. In addition, this method contributes to reduction in greenhouse gas emissions by diverting waste from landfills where its decomposition would have generated methane, one of the potent greenhouse gases. However, it must be noted that the start-up costs for waste-to-energy operations that meet the current stringent federal and state regulations may make this disposal method economically unfeasible for some areas. In addition, there has been a strong public opposition to incineration in the past due to harmful emissions, in spite of advances in technology and process enhancements, that opposition remains.
Combustion for volume reduction
One of the more recent technologies in this area is Plasma Arc which is a form of waste disposal in which waste is converted into gas and slag by means of high temperature and electric energy. The emerging gas can be used as an energy source in a boiler or turbine. St. Lucie county in Florida is investing $425 million in a facility that will vaporize 3,000 tons of garbage per day to create 120 megawatts of electricity to be sold to the grid- enough to power 106,000 homes (Sladky, 2006). Resulting emissions are expected to be quite low and meeting the air pollution requirements of the Clean Air Act. The technology has been used in Japan since 1999.
Methane is created as solid waste decomposes in a landfill. This gas is the primary component of natural gas (USEPA, 2008). Methane is a powerful greenhouse gas that can alternatively be captured, converted and used as an energy source. After collection and processing, the gas can be used to generate electricity, replace fossil fuels in industrial/manufacturing processes or be upgraded to pipeline quality gas. In addition to reduction in greenhouse gas emissions, such landfill gas energy projects offset the use of non-renewable resources, reduce landfill odors and explosion hazards as well as improve local economies by creating jobs and providing alternative energy sources. NASA, Nestle, GM, Ford and Rolls Royce are some of the companies that use methane as an alternative fuel. Although there is one operational landfill gas energy project and a candidate landfill for a potential project in Illinois, neither are in the Chicago metro region.