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Special Issue "Waste to Energy Technologies"

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A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (30 June 2012)

Special Issue Editors

Guest Editor
Prof. Dr. Frank J. Roethel

School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000, USA
Interests: chemistry and environmental behavior of combustion by-products, beneficial utilization of combustion by-products, waste-to-energy combustor ash characteristics, marine applications associated with combustion by-products
Guest Editor
Prof. Dr. Stephen Joseph

School of Materials Science & Engineering, The University of New South Wales, Sydney NSW 2052, Australia

Special Issue Information

Dear Colleagues,

Today’s diverse solid waste management plans, implemented internationally, include, reducing, recycling, reusing as much waste as practicable but what remains is either landfilled or combusted at waste-to-energy facilities.  Electricity and/or steam are produced in modern waste-to-energy facilities while metals are recovered and recycled.  In many regions of the world, the bottom ash, which represents 85% of the combustion residuals, is processed creating an engineered aggregate and used in diverse applications.  The remaining fly ash is typically treated and disposed.  This special issue will focus, in part, on advances in facility design, implementation of state of the art air pollution control strategies, metal recovery and recycling, ash management and beneficial utilization and the differences in regulations and permitting implemented by various nations. Submissions addressing the environmental implications associated with incorporating waste-to-energy as a solid waste management strategy are encouraged.  A primary goal of this special issue is to compile a global perspective on waste-to-energy technology and the associated issues surrounding this waste management strategy.

Prof. Dr. Frank J. Roethel
Prof. Dr. Stephen Joseph
Guest Editors

Keywords

  • Waste-to-energy (WTE)
  • Air pollution control technology
  • Metal recovery
  • Ash management
  • WTE Regulations and policy
  • WTE Environmental perspectives

Published Papers (9 papers)

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Research

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Open AccessArticle Linear Active Disturbance Rejection Control of Waste Heat Recovery Systems with Organic Rankine Cycles
Energies 2012, 5(12), 5111-5125; doi:10.3390/en5125111
Received: 23 August 2012 / Revised: 3 November 2012 / Accepted: 21 November 2012 / Published: 4 December 2012
Cited by 7 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a linear active disturbance rejection controller is proposed for a waste heat recovery system using an organic Rankine cycle process, whose model is obtained by applying the system identification technique. The disturbances imposed on the waste heat recovery system [...] Read more.
In this paper, a linear active disturbance rejection controller is proposed for a waste heat recovery system using an organic Rankine cycle process, whose model is obtained by applying the system identification technique. The disturbances imposed on the waste heat recovery system are estimated through an extended linear state observer and then compensated by a linear feedback control strategy. The proposed control strategy is applied to a 100 kW waste heat recovery system to handle the power demand variations of grid and process disturbances. The effectiveness of this controller is verified via a simulation study, and the results demonstrate that the proposed strategy can provide satisfactory tracking performance and disturbance rejection. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle Combustion Characteristics of Chlorine-Free Solid Fuel Produced from Municipal Solid Waste by Hydrothermal Processing
Energies 2012, 5(11), 4446-4461; doi:10.3390/en5114446
Received: 3 September 2012 / Revised: 24 October 2012 / Accepted: 24 October 2012 / Published: 8 November 2012
Cited by 1 | PDF Full-text (714 KB) | HTML Full-text | XML Full-text
Abstract
An experimental study on converting municipal solid waste (MSW) into chlorine-free solid fuel using a combination of hydrothermal processing and water-washing has been performed. After the product was extracted from the reactor, water-washing experiments were then conducted to obtain chlorine-free products with [...] Read more.
An experimental study on converting municipal solid waste (MSW) into chlorine-free solid fuel using a combination of hydrothermal processing and water-washing has been performed. After the product was extracted from the reactor, water-washing experiments were then conducted to obtain chlorine-free products with less than 3000 ppm total chlorine content. A series of combustion experiments were then performed for the products before and after the washing process to determine the chlorine content in the exhaust gas and those left in the ash after the combustion process at a certain temperature. A series of thermogravimetric analyses were also conducted to compare the combustion characteristics of the products before and after the washing process. Due to the loss of ash and some volatile matter after washing process, there were increases in the fixed carbon content and the heating value of the product. Considering the possible chlorine emission, the washing process after the hydrothermal treatment should be necessary only if the furnace temperature is more than 800 °C. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle Collection of Thermal Energy Available from a Biogas Plant for Leachate Treatment in an Urban Landfill: A Sicilian Case Study
Energies 2012, 5(10), 3753-3767; doi:10.3390/en5103753
Received: 31 July 2012 / Revised: 20 September 2012 / Accepted: 21 September 2012 / Published: 26 September 2012
Cited by 3 | PDF Full-text (641 KB) | HTML Full-text | XML Full-text
Abstract
The landfill of Bellolampo is located in northern Sicily and serves the greater area of Palermo (Sicily). In the recent past, the landfill has been progressively renovated in order to align the waste disposal process with the state-of-the-art technology. During the past [...] Read more.
The landfill of Bellolampo is located in northern Sicily and serves the greater area of Palermo (Sicily). In the recent past, the landfill has been progressively renovated in order to align the waste disposal process with the state-of-the-art technology. During the past years, the site had been equipped with seven biogas engines, fuelled with the biogas produced at the oldest part of the landfill. More recently, another two engines of the same type have been installed for a total of 9 MW electrical power installed at the landfill. The landfill of Bellolampo faces a significant leachate disposal problem. Some 250 m3 of contaminated leachate are produced daily and transported by ships and trucks to an area about 1000 km away before being treated and disposed. The disposal of this extremely polluting fluid causes significant nuisance in the integrated waste management process and significant disposal expenses (in excess of € 60 per ton of fluid disposed and € 4.5 mln per year). Furthermore, the recent legislation strongly suggests the landfill manager to activate fully integrated systems and 100% landfill auto-sustainability. On the other hand, the above mentioned biogas engines produce a great quantity of unused thermal energy yearly. This study demonstrates that this energy could be effectively and efficiently used to enable the sustainable in-house treatment of the leachate. The treatment is aimed to significantly reduce leachate volume in order to reduce fluid disposal costs. A thorough economical analysis is also performed. The study demonstrates that a medium sized landfill can sustainably and cost-effectively be managed through a fully integrated system thus producing substantial economies. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle Kinetic Study of the Pyrolysis of Waste Printed Circuit Boards Subject to Conventional and Microwave Heating
Energies 2012, 5(9), 3295-3306; doi:10.3390/en5093295
Received: 2 July 2012 / Revised: 8 August 2012 / Accepted: 24 August 2012 / Published: 31 August 2012
Cited by 7 | PDF Full-text (433 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a kinetic study of the decomposition of waste printed circuit boards (WPCB) under conventional and microwave-induced pyrolysis conditions. We discuss the heating rates and the influence of the pyrolysis on the thermal decomposition kinetics of WPCB. We find that [...] Read more.
This paper describes a kinetic study of the decomposition of waste printed circuit boards (WPCB) under conventional and microwave-induced pyrolysis conditions. We discuss the heating rates and the influence of the pyrolysis on the thermal decomposition kinetics of WPCB. We find that the thermal degradation of WPCB in a controlled conventional thermogravimetric analyzer (TGA) occurred in the temperature range of 300 °C–600 °C, where the main pyrolysis of organic matter takes place along with an expulsion of volumetric volatiles. The corresponding activation energy is decreased from 267 kJ/mol to 168 kJ/mol with increased heating rates from 20 °C/min to 50 °C/min. Similarly, the process of microwave-induced pyrolysis of WPCB material manifests in only one stage, judging by experiments with a microwave power of 700 W. Here, the activation energy is determined to be only 49 kJ/mol, much lower than that found in a conventional TGA subject to a similar heating rate. The low activation energy found in microwave-induced pyrolysis suggests that the adoption of microwave technology for the disposal of WPCB material and even for waste electronic and electrical equipment (WEEE) could be an attractive option. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle Performance Analysis and Working Fluid Selection of a Supercritical Organic Rankine Cycle for Low Grade Waste Heat Recovery
Energies 2012, 5(9), 3233-3247; doi:10.3390/en5093233
Received: 10 July 2012 / Revised: 15 August 2012 / Accepted: 23 August 2012 / Published: 30 August 2012
Cited by 39 | PDF Full-text (437 KB) | HTML Full-text | XML Full-text
Abstract
The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP), and heat exchanger requirement of [...] Read more.
The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP), and heat exchanger requirement of evaporator and the condenser, were used to evaluate the performance of this recovery cycle and screen the working fluids. The results reveal that in most cases, raising the expander inlet temperature is helpful to improve the net power output and the exergy efficiency. However, the effect of the expander inlet pressure on those parameters is related to the expander inlet temperature and working fluid used. Either lower expander inlet temperature and pressure, or higher expander inlet temperature and pressure, generally makes the net power output more. Lower expander inlet temperature results in larger total heat transfer requirement and expander size. According to the screening criteria of both the higher output and the lower investment, the following working fluids for the supercritical ORC system are recommended: R152a and R143a. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle An Analysis of the Use of Biosludge as an Energy Source and Its Environmental Benefits in Taiwan
Energies 2012, 5(8), 3064-3073; doi:10.3390/en5083064
Received: 2 July 2012 / Revised: 25 July 2012 / Accepted: 2 August 2012 / Published: 14 August 2012
Cited by 4 | PDF Full-text (192 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this paper was to provide a preliminary analysis of energy utilization from biological wastewater treatment sludge (biosludge) in Taiwan, a densely populated country (estimate 640 persons/km2) with a high dependence (over 99%) on imported energy. The discussion [...] Read more.
The objective of this paper was to provide a preliminary analysis of energy utilization from biological wastewater treatment sludge (biosludge) in Taiwan, a densely populated country (estimate 640 persons/km2) with a high dependence (over 99%) on imported energy. The discussion focused on the status of biosludge generation and its management in the years 2004–2010. Findings showed that the main types of combustible waste (i.e., biosludge) produced by the industrial and agricultural sectors of Taiwan included food processing sludge, wine brewery sludge and agricultural sludge which may be reused as auxiliary fuel in the utilities (e.g., generator, boiler and incinerator). Furthermore, two conceptual biosludge-to-energy systems have been addressed with regard to the thermochemical conversion processes. One is to adopt direct combustion for power generation in the combined heat and power system. Another system uses pyrolysis and gasification for producing biochar (solid fuel), bio-oil (liquid fuel) and syngas (gas fuel). Based on their thermochemical properties and reported generation quantities, the energy potential and the environmental benefits of mitigating CO2 emissions were also analyzed in the study, showing around 1.1 × 103 TJ/year and 57 Gg CO2/year, respectively. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessArticle Reciprocating Expander for an Exhaust Heat Recovery Rankine Cycle for a Passenger Car Application
Energies 2012, 5(6), 1751-1765; doi:10.3390/en5061751
Received: 10 April 2012 / Revised: 25 May 2012 / Accepted: 28 May 2012 / Published: 5 June 2012
Cited by 17 | PDF Full-text (247 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, on average, two thirds of the fuel energy consumed by an engine is wasted through the exhaust gases and the cooling liquid. The recovery of this energy would enable a substantial reduction in fuel consumption. One solution is to integrate a [...] Read more.
Nowadays, on average, two thirds of the fuel energy consumed by an engine is wasted through the exhaust gases and the cooling liquid. The recovery of this energy would enable a substantial reduction in fuel consumption. One solution is to integrate a heat recovery system based on a steam Rankine cycle. The key component in such a system is the expander, which has a strong impact on the system’s performance. A survey of different expander technologies leads us to select the reciprocating expander as the most promising one for an automotive application. This paper therefore proposes a steady-state semi-empirical model of the expander device developed under the Engineering Equation Solver (EES) environment. The ambient and mechanical losses as well as internal leakage were taken into account by the model. By exploiting the expander manufacturer’s data, all the parameters of the expander model were identified. The model computes the mass flow rate, the power output delivered and the exhaust enthalpy of the steam. The maximum deviation between predictions and measurement data is 4.7%. A performance study of the expander is carried out and shows that the isentropic efficiency is quite high and increases with the expander rotary speed. The mechanical efficiency depends on mechanical losses which are quite high, approximately 90%. The volumetric efficiency was also evaluated. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)

Review

Jump to: Research

Open AccessReview A Review on Waste to Energy Processes Using Microwave Pyrolysis
Energies 2012, 5(10), 4209-4232; doi:10.3390/en5104209
Received: 29 June 2012 / Revised: 6 September 2012 / Accepted: 12 October 2012 / Published: 23 October 2012
Cited by 41 | PDF Full-text (658 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an extensive review of the scientific literature associated with various microwave pyrolysis applications in waste to energy engineering. It was established that microwave-heated pyrolysis processes offer a number of advantages over other processes that use traditional thermal heat sources. [...] Read more.
This paper presents an extensive review of the scientific literature associated with various microwave pyrolysis applications in waste to energy engineering. It was established that microwave-heated pyrolysis processes offer a number of advantages over other processes that use traditional thermal heat sources. In particular, microwave-heated processes show a distinct advantage in providing rapid and energy-efficient heating compared to conventional technologies, and thus facilitating increased production rates. It can also be established that the pyrolysis process offers an exciting way to recover both the energetic and chemical value of the waste materials by generating potentially useful pyrolysis products suitable for future reuse. Furthermore, this review has revealed good performance of the microwave pyrolysis process when compared to other more conventional methods of operation, indicating that it shows exceptional promise as a means for energy recovery from waste materials. Nonetheless, it was revealed that many important characteristics of the microwave pyrolysis process have yet to be raised or fully investigated. In addition, limited information is available concerning the characteristics of the microwave pyrolysis of waste materials. It was thus concluded that more work is needed to extend existing understanding of these aspects in order to develop improvements to the process to transform it into a commercially viable route to recover energy from waste materials in an environmentally sustainable manner. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)
Open AccessReview Ash Management Review—Applications of Biomass Bottom Ash
Energies 2012, 5(10), 3856-3873; doi:10.3390/en5103856
Received: 18 July 2012 / Revised: 13 September 2012 / Accepted: 20 September 2012 / Published: 9 October 2012
Cited by 32 | PDF Full-text (210 KB) | HTML Full-text | XML Full-text
Abstract
In industrialized countries, it is expected that the future generation of bioenergy will be from the direct combustion of residues and wastes obtained from biomass. Bioenergy production using woody biomass is a fast developing application since this fuel source is considered to [...] Read more.
In industrialized countries, it is expected that the future generation of bioenergy will be from the direct combustion of residues and wastes obtained from biomass. Bioenergy production using woody biomass is a fast developing application since this fuel source is considered to be carbon neutral. The harnessing of bioenergy from these sources produces residue in the form of ash. As the demand for bioenergy production increases, ash and residue volumes will increase. Major challenges will arise relating to the efficient management of these byproducts. The primary concerns for ash are its storage, disposal, use and the presence of unburned carbon. The continual increase in ash volume will result in decreased ash storage facilities (in cases of limited room for landfill expansion), as well as increased handling, transporting and spreading costs. The utilization of ash has been the focus of many studies, hence this review investigates the likely environmental and technological challenges that increased ash generation may cause. The presence of alkali metals, alkaline earth metals, chlorine, sulphur and silicon influences the reactivity and leaching to the inorganic phases which may have significant impacts on soils and the recycling of soil nutrient. Discussed are some of the existing technologies for the processing of ash. Unburned carbon present in ash allows for the exploration of using ash as a fuel. The paper proposes sieve fractionation as a suitable method for the separation of unburnt carbon present in bottom ash obtained from a fixed-bed combustion system, followed by the application of the gasification technology to particle sizes of energy importance. It is hoped that this process will significantly reduce the volume of ash disposed at landfills. Full article
(This article belongs to the Special Issue Waste to Energy Technologies)

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