2001 Progress Report: New Methods for Assessment of Pollution Prevention TechnologiesEPA Grant Number: R826739
Title: New Methods for Assessment of Pollution Prevention Technologies
Investigators: Frey, H. Christopher , Barlaz, Morton A.
Institution: North Carolina State University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1998 through September 30, 1999 (Extended to September 30, 2003)
Project Period Covered by this Report: October 1, 2000 through September 30, 2001
Project Amount: $180,000
RFA: Technology for a Sustainable Environment (1998) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
The objectives of this research are to: (1) develop novel assessment methodologies for evaluation of the risks and potential pay-offs of new technologies that avoid pollutant production; (2) demonstrate the methodology via a detailed case study of one promising new pollution prevention technology; and (3) utilize a tiered approach including process simulation and design optimization, probabilistic analysis, life cycle analysis, and assessment of selected regional environmental impacts to provide insights regarding the risks and pay-offs of the pollution prevention approach, both at a "micro" process-level and at a "macro" regional environmental level.
Toward the objectives, activities having included the following: (1) identify specific process technologies for detailed evaluation, based upon a solid waste-fueled gasification combined cycle system capable of coproduction of electricity, steam, sulfur, methanol, and ammonia; (2) develop design bases for major components of the system, including gasification, gas cooling, gas cleanup, gas turbine, and methanol synthesis; (3) implement process simulation models of the major components using ASPEN Plus; (4) obtain and evaluate life cycle inventory data regarding conventional methods for power generation, sulfur production, steam production, methanol synthesis, and ammonia synthesis; (5) develop a corresponding life cycle inventory model; and (6) apply the models to case studies.
Case studies have recently been completed for three scenarios involving the use of MSW as a gasification and polygeneration feedstock. The three scenarios were designed to evaluate the LCI of MSW gasification. The IGCC plant size was varied in each scenario by varying methanol production. The size of the methanol production plant was set at 4,536, 9,072 and 18,144 kg/hr in scenarios A, B and C, respectively. In each scenario, the size of the two gas turbines modeled in the IGCC system model was held constant. Then a case study was conducted to compare two competing processes for MSW management, one involving MSW gasification and one involving a conventional mass burn WTE facility. For each scenario, a series of model runs was made to determine (1) material usage, material production, energy production, and the emissions associated with gasification of the RDF/coal blends, (2) material usage, material production, energy production and emissions that could be attributed to RDF production and (3) the environmental burdens associated with the application of gasification technology to MSW. For each of the three scenarios, two cases were considered. In case 1, the MSW residual from RDF production is disposed in a traditional landfill with no energy recovery. In case 2, the MSW residual is disposed in a traditional landfill with electrical energy recovery.
The case study demonstrated that both the gasification process and mass burn combustion of MSW result in avoided emissions due to the recovery of beneficial products including energy, recyclables, and methanol in the case of gasification. The largest contributors to emissions are the offset emissions associated with the ferrous and aluminum recovered in the RDF plant and the offset emissions associated with the recovered electricity. The LCI comparison showed that the WTE system produced 1.5 ~ 2 times more emissions than the gasification system for most parameters. The gasification system also produces about 1.5 times more electricity than the WTE system. Sulfur is produced during gas cleanup in the gasification process and no offset was calculated for the recovery of this sulfur. In addition, the product syngas may be used for ammonia production that would also be likely to improve the LCI of waste gasification. As such, the results showing that gasification of MSW coal blends results in reduced emissions relative to a mass burn process are conservative in that they do not fully quantify the environmental benefits of gasification. Through the case study conducted in this project, the environmental benefits of a new technology have been quantified by the development of appropriate process models and the use of life-cycle analysis.
The main focus of work in the remaining year of the project is to complete the impact assessment based upon specific scenarios for the use of MSW as a feedstock for gasification polygeneration systems.