Fly Ash from Municipal Solid Waste Incineration as a Potential Thermochemical Energy Storage Material

Abstract

Each year, combustion at municipal solid waste incineration (MSWI) plants produces millions of tons of fly ash globally. This ash is characterized as a hazardous material and is mostly placed in landfills after a stabilization process or stored in hazardous waste sites. Thus, disposal of fly ash leaves a considerable social and environmental footprint and leads to high waste management costs. Thermochemical energy storage (TCES) systems are considered to be outstanding because of their high-energy density and near-zero energy loss over long periods of time. Calcium oxide (CaO), a main MSWI fly ash component, is a promising candidate for TCES. In this study, we investigate the potential of fly ash as a TCES material. To do so, we analyzed representative samples from different MSWIs using simultaneous thermal analysis (STA) under N2, CO2, and CO2/H2O atmospheres. These analyses were supported by additional techniques such as X-ray fluorescence (XRF) spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM). The STA results illustrate fly ash reactivity under different atmospheres. All samples could store heat through endothermic reactions and one sample was able to release stored heat under selected operating conditions. XRF analysis verified an average fly ash composition of 27% CaO, ICP-OES analysis demonstrated the presence of different heavy metals, and SEM analysis revealed the sintering and agglomeration of fly ash particles at high temperatures (1150 °C). This study shows that the use of fly ash as a TCES material is promising and that further investigation in the field is needed to corroborate this application.

Comparing Fly Ash Samples from Different Types of Incinerators for Their Potential as Storage Materials for Thermochemical Energy and CO2

“…The first mass loss up to 500 °C occurs because of desorption of physically and chemically adsorbed water combined with volatilization of organic components and volatile elements existing in fly ash samples [15,50,51]. The mass loss continues in the temperature range 530 °C–770 °C, and an average mass loss of approximately 4% is observed for fly ashes A, B, and C-filter.…”

“…Cherbasnki et al presented the CO 2 sorption properties of fly ash for methane steam reforming [14]. Moreover, a possible application for MSWI fly ash samples as thermochemical energy storage (TCES) materials was reported by Setoodeh et al [15]. TCES technology has been under development worldwide during the last decades, and interest in the industrial implementation of this type of energy storage system is increasing.…”

“…CaO, along with Al 2 O 3 , SiO 2 , and metal salts, is a main component of fly ash and a promising potential candidate for TCES systems [15]. One special feature of CaO is its ability to reversibly react with water vapor (H 2 O (g) ) and carbon dioxide (CO 2 ) to build two TCES systems (Equations (1) and (2)/at 25 °C).…”

“…In our earlier investigation, three fly ash samples from the same technology (grate furnaces) were chemically characterized for their application as TCES materials. Results revealed that all three fly ash samples could store heat, and one fly ash could release the stored heat under designated conditions [15]. To obtain the complete spectra of various fly ash samples obtained from different types of incinerators to determine their TCES and CO 2 storage potential, extensive characterization of samples from grate furnaces, rotary kiln, and fluidized bed was performed.…”

Comparison of the Characteristics of Fly Ash Generated from Bio and Municipal Waste: Fluidized Bed Incinerators

“…This study aims to collect detailed information on the physical and chemical characterization, particle size distribution, mineralogy, morphology, heavy metal content, and leaching behavior of the fly ash generated by two different fluidized bed incinerators, originating from the input feed of municipal solid waste and biomass. This research is part of a major project in which fly ash from different type of incinerators (grate furnace, fluidized bed, and rotary kiln) is being investigated to identify possible utilization opportunities for the fly ash in order to achieve less dependence on landfill [16].…”