Process simulation development of a clean waste-to-energy conversion power plant: Thermodynamic and environmental assessment

Po-Chih Kuo,Biju Illathukandy,Chi-Hsiu Kung,Jo-Shu Chang,Wei Wu

doi:10.1016/j.jclepro.2021.128156

Abstract

Waste-to-energy (WTE) conversion technologies for generating renewable energy and solving the environmental problems have an important role in the development of sustainable circular economy. This paper presents a novel high-efficiency WTE power plant using refuse-derived fuel (RDF) as feedstock by integrating torrefaction (T) pretreatment with plasma gasifier (PG), solid oxide fuel cell (SOFC), and combined heat and power (CHP) system. The combined impacts of torrefaction conditions (i.e. temperature and residence time) and steam-to-fuel (S/F) ratio on the energy and environmental performances of the proposed T-PG-SOFC-CHP power plant without CO2 capture (System I) is first evaluated. Results show that torrefaction of RDF prior to plasma gasification provides better syngas quality and therefore the system electrical efficiency (SEE) and CHP efficiency (CHPE) of System I can be markedly boosted compared to that of untreated RDF. However, the integration of torrefaction unit shows a negative effect on the energy return on investment (EROI) due to high energy demands for torrefaction and plasma gasification. Overall, the values of CHPE of System I range from 47.25% to 55.39% when the torrefaction temperatures of 200 and 250 °C are adopted. In contrast, the torrefaction of RDF at 300 °C is not a recommended condition for operation in the T-PG-SOFC-CHP power plant because of noticeably negative energy and environmental impacts. Moreover, to prevent the risk of carbon deposition on the SOFC anode, a recirculation ratio (RR) of the anode off-gas of 30% is required. Finally, the introduction of oxy-fuel combustion technology into the T-PG-SOFC-CHP system for CO2 capture (System II) allows to achieve a zero direct CO2 emission WTE power plant. However, this results in an energy penalty of about 5.40–6.77% associated with the CO2 capture and compression process.

Highlights

With the significantly increasing growth of global population, economy, and urbanization, the amount of waste produced by different industrial sectors are increasing at a quick rate
This will lead to substantial amount of CO2 emissions to the environment if the waste is landfilled without energy recovery (Manfredi et al, 2009)
The second aim of this study is to design a new oxy-fuel combus tion-based T-plasma gasifier (PG)-solid oxide fuel cell (SOFC)-combined heat and power (CHP) power plant for achieving zero direct CO2 emissions (System II) and to compare its energy and environmental performances with System I

Summary

Introduction

With the significantly increasing growth of global population, economy, and urbanization, the amount of waste produced by different industrial sectors are increasing at a quick rate. According to the “World Bank Group’s” report, global annual waste production is esti mated to increase from 2.01 billion tons in 2016 to 3.40 billion tons by 2050, accounting for a rise of around 70% (Kaza et al, 2018). This will lead to substantial amount of CO2 emissions to the environment if the waste is landfilled without energy recovery (Manfredi et al, 2009). To improve waste management and sustainability, in the recent years, efficient waste-to-energy (WTE) conversion technologies have received considerable attention world wide (Putna et al, 2020). The desired quality of syngas (H2+CO), depending on the type of gasifying

Objectives

Results

Conclusion