Plasma gasification of municipal solid waste for waste-to-value processing

https://doi.org/10.1016/j.rser.2019.109461Get rights and content

Highlights

  • Plasma gasification can be a viable technology for the circular economy.

  • The present study reviewed the current status of plasma gasification for waste-to-value processing.

  • A roadmap for the successful commercialisation of plasma gasification was suggested.

Abstract

Plasma gasification can be a viable technology for converting municipal solid waste (MSW) into value for the circular economy. However, in its current state, plasma gasification is mostly limited to lab or pilot scales as there are various challenges associated with it; there exist knowledge gaps which need attention and research for its successful future commercialisation. The present study critically reviewed the current status of plasma gasification for waste-to-value processing. Various traditional techniques for MSW disposal and processing available in the literature were discussed and were compared with plasma gasification in terms of cost, service life, energy comparison, and environmental impact comparison. After the review, knowledge gaps were identified, challenges associated with the plasma gasification technology were discussed, and a possible roadmap for the successful future commercialisation of plasma gasification for waste-to-value processing was suggested. Furthermore, various strategies to cope with challenges associated with plasma gasification were discussed. The successful commercialisation of plasma gasification can be achieved by reducing its costs by generating revenue or value in the form of synthesis gas or fuels from MSW, energy can be saved or reused using insulation, process integration, and process intensification, the technology and community readiness levels can be improved with better communication between relevant stakeholders and adding extra layers of safety, and process understanding can be improved by conducting extensive fundamental studies, as well as plasma gasification technology being standardised by establishing standards and standards organisations.

Introduction

Municipal solid waste (MSW) is generated in large quantities worldwide and its generation is expected to increase due to swift urbanisation and the resulting change in lifestyle. Globally, approximately 1.5 billion metric tonnes per year of MSW was produced in recent years and its generation is expected to increase to approximately 2.5 billion metric tonnes per year by 2025 [1]. The generation of MSW has also increased in New Zealand during recent years and has reached approximately 3.2 million tonnes per year, Fig. 1(a). Fig. 1 is the plotted MSW generation data, presented in the recent literature such as [1], and [2].

Proper waste management of such a huge amount of MSW is required to protect the environment from land and air pollution, and for the health and safety of humans and animals. The majority of MSW is landfilled in most countries. For example, in New Zealand, a majority of MSW that contains fractions of organic and inorganic materials (Fig. 1(b)) is sent to landfills [2]. Landfilling and associated recycling and collection strategies of MSW have been optimised over time; however, rapid accumulation of MSW, increasing cost of landfills, and landfill problems (e.g. toxins and leachate) are stressing city governments to find new sustainable techniques to cost-effectively dispose of MSW. Furthermore, landfilling can cause significant loss to the circular economy. For the circular economy, waste needs to be transformed into value (waste-to-resource (e.g. energy)) through effective waste treatment. Therefore, MSW needs to be ‘processed’ to value (i.e. waste-to-energy) for the circular economy, managing increasing demand of energy, and offset energy costs of waste-to-value processes.

Various techniques for MSW disposal and processing are available in the literature as an alternate of landfilling [3]. Waste can be disposed and processed using biological (e.g. composting, aerobic and anaerobic digestion) [4], hydrothermal (e.g. wet oxidation, thermal hydrolysis, liquefaction, and carbonisation) [5], and thermochemical (e.g. gasification, pyrolysis, and incineration) techniques [6,7]. These techniques can be used for waste disposal and waste-to-value processing [8]. Each technique has its pros and cons. Biological techniques convert MSW to biogas or compost, and are environmentally ‘safe’, but are expensive and time-consuming because they require a large area, are inefficient for hazardous waste, and biological degradation is a slow process [9,10]. Hydrothermal techniques reduce MSW volume, extract valuables from waste, and are relatively faster and environmentally ‘safe’, but have higher operational costs due to associated energy costs and are not operationally ‘safe’ as they have associated safety issues due to the required extreme conditions of temperature and pressure [3]. Thermochemical techniques convert MSW to charcoal, oil, syngas, or heat, and are also faster and environmentally ‘safe’, but have high operational costs [11].

Thermochemical techniques have been used for waste disposal and waste-to-value processing, as confirmed by several studies on incineration [[12], [13], [14]], steam gasification [8,[15], [16], [17]], and pyrolysis [[18], [19], [20], [21]]. However, limited studies on plasma gasification (an emerging thermochemical technique) have been conducted. This observation may be due to various challenges associated with plasma gasification such as its being a relatively new technology, requiring high capital & operational costs, is a highly energy-intensive process, has only a moderate technology & community readiness level, the requirement of proper waste sorting, the limited technology commercialisation success, and currently limited process understanding. These challenges are discussed in detail in Section 3. Plasma gasification has mainly been used for treating hazardous waste, and its use for waste-to-value processing is relatively new.

Plasma gasification can be a suitable technique for waste disposal and waste-to-value processing because it can extract recyclable commodities from landfill waste and can convert carbon-based waste materials into syngas and fuels. In other words, plasma gasification can help to achieve zero-waste accumulation, produce renewable fuels, and protect the environment.

This article reviews the current status of waste-to-value (municipal solid waste-to-syngas and other valuable products) processing using plasma gasification for the circular economy. Key findings and knowledge gaps were identified in ‘successful’ industrial application of plasma gasification for waste-to-value processing. After discussing challenges associated with the technology, a possible roadmap for ‘successful’ industrial application of plasma gasification was suggested in this study. Previously, various review articles on plasma gasification have been published such as Gomez et al. (2009) [22], Morrin et al. (2012) [23], Fabry et al. (2013) [24], Sanlisoy et al. (2017) [25], and Changming et al. (2018) [26]. However, it was difficult to find a study in the literature identifying challenges associated with plasma gasification for its ‘successful’ industrial application (novelty of the present study), especially for waste-to-value processing.

Section snippets

Introduction to plasma gasification

Plasma gasification has existed for many years since NASA advanced the process in the 1970s [27]. Plasma gasification is a thermal process in which waste is exposed to extreme thermal conditions (approximately 2000–14,000 °C) of plasma. Fig. 2 shows a schematic of plasma gasification of MSW. Plasma is the fourth state of matter, obtained by breaking atoms and molecules down to constituent ions and electrons after electrifying a gas [28]. Zhang et al. (2012) [6] showed a typical schematic of a

Key findings, knowledge gaps, and challenges associated with plasma gasification

After reviewing recent literature, it is evident that many studies claim promising capabilities of plasma gasification to convert MSW into value. There are, however, various challenges associated with the plasma gasification of MSW that need to be addressed and dealt with before successful industrial application can be achieved. The main challenges associated with plasma gasification for waste-to-value processing are displayed in Fig. 4.

Plasma gasification is a relatively expensive technology

Suggested road map for coping with plasma gasification challenges

Plasma gasification for waste-to-value processing for the circular economy has several challenges to overcome, discussed in Section 3, and can take many years to go from discovery to successful commercial use.

Conclusions

Plasma gasification can be a viable technology for waste-to-value processing for the circular economy; however, there are various challenges associated with plasma gasification which require attention for the successful, future commercialisation of plasma gasification. Reduction of initial capital costs of plasma gasification does not seem realistic; however, its operational costs can be targeted for reduction by generating revenue from synthesis gas and fuels produced from the process. Energy

Acknowledgement

The authors gratefully acknowledge Rotorua Lakes Council (RLC) New Zealand, Porirua City Council New Zealand, the University of Auckland New Zealand, and the American University of the Middle East Kuwait for their support.

References (86)

  • J. Wang et al.

    Hydrogen-rich gas production by steam gasification of municipal solid waste (MSW) using NiO supported on modified dolomite

    Int J Hydrogen Energy

    (2012)
  • S. Luo et al.

    Syngas production by catalytic steam gasification of municipal solid waste in fixed-bed reactor

    Energy

    (2012)
  • Y. Guan et al.

    Steam catalytic gasification of municipal solid waste for producing tar-free fuel gas

    Int J Hydrogen Energy

    (2009)
  • I. Velghe et al.

    Study of the pyrolysis of municipal solid waste for the production of valuable products

    J Anal Appl Pyrolysis

    (2011)
  • D. Chen et al.

    Reprint of: pyrolysis technologies for municipal solid waste: a review

    Waste Manag

    (2015)
  • M. He et al.

    Syngas production from pyrolysis of municipal solid waste (MSW) with dolomite as downstream catalysts

    J Anal Appl Pyrolysis

    (2010)
  • S. Luo et al.

    Influence of particle size on pyrolysis and gasification performance of municipal solid waste in a fixed bed reactor

    Bioresour Technol

    (2010)
  • E. Gomez et al.

    Thermal plasma technology for the treatment of wastes: a critical review

    J Hazard Mater

    (2009)
  • S. Morrin et al.

    Two stage fluid bed-plasma gasification process for solid waste valorisation: technical review and preliminary thermodynamic modelling of sulphur emissions

    Waste Manag

    (2012)
  • A. Sanlisoy et al.

    A review on plasma gasification for solid waste disposal

    Int J Hydrogen Energy

    (2017)
  • D. Changming et al.

    Plasma methods for metals recovery from metal–containing waste

    Waste Manag

    (2018)
  • L. Mazzoni et al.

    Plasma gasification of municipal solid waste with variable content of plastic solid waste for enhanced energy recovery

    Int J Hydrogen Energy

    (2017)
  • S.A. Salaudeen et al.

    10 - gasification of plastic solid waste and competitive technologies

  • P. Breeze

    Chapter 7 - advanced waste-to-energy technologies: gasification, pyrolysis, and plasma gasification

  • G. Lopez et al.

    Recent advances in the gasification of waste plastics. A critical overview

    Renew Sustain Energy Rev

    (2018)
  • P.R. Bhoi et al.

    Co-gasification of municipal solid waste and biomass in a commercial scale downdraft gasifier

    Energy

    (2018)
  • R. Tavares et al.

    A theoretical study on municipal solid waste plasma gasification

    Waste Manag

    (2019)
  • L. Mazzoni et al.

    A comparison of energy recovery from MSW through plasma gasification and entrained flow gasification

    Energy Procedia

    (2017)
  • P.G. Rutberg et al.

    On efficiency of plasma gasification of wood residues

    Biomass Bioenergy

    (2011)
  • C.J. Lupa et al.

    Experimental analysis of biomass pyrolysis using microwave-induced plasma

    Fuel Process Technol

    (2012)
  • J.-L. Shie et al.

    Bioenergy and products from thermal pyrolysis of rice straw using plasma torch

    Bioresour Technol

    (2010)
  • V.E. Messerle et al.

    Processing of biomedical waste in plasma gasifier

    Waste Manag

    (2018)
  • J. Zeng et al.

    Co-treatment of hazardous wastes by the thermal plasma to produce an effective catalyst

    J Clean Prod

    (2019)
  • X. Pan et al.

    Detoxifying PCDD/Fs and heavy metals in fly ash from medical waste incinerators with a DC double arc plasma torch

    J Environ Sci

    (2013)
  • L. Mazzoni et al.

    Plasma gasification of two waste streams: municipal solid waste and hazardous waste from the oil and gas industry

    Energy Procedia

    (2017)
  • A. Tamošiūnas et al.

    Thermal arc plasma gasification of waste glycerol to syngas

    Appl Energy

    (2019)
  • M. Materazzi et al.

    Production of biohydrogen from gasification of waste fuels: pilot plant results and deployment prospects

    Waste Manag

    (2019)
  • M. Wang et al.

    Highly efficient treatment of textile dyeing sludge by CO2 thermal plasma gasification

    Waste Manag

    (2019)
  • K. Moustakas et al.

    Demonstration plasma gasification/vitrification system for effective hazardous waste treatment

    J Hazard Mater

    (2005)
  • D. McLaren

    A comparative global assessment of potential negative emissions technologies

    Process Saf Environ Prot

    (2012)
  • L.S. Mapamba et al.

    Technology assessment of plasma arc reforming for greenhouse gas mitigation: a simulation study applied to a coal to liquids process

    J Clean Prod

    (2016)
  • S. Saini et al.

    City based analysis of MSW to energy generation in India, calculation of state-wise potential and tariff comparison with EU

    Procedia Soc Behav Sci

    (2012)
  • L. Tang et al.

    Development of plasma pyrolysis/gasification systems for energy efficient and environmentally sound waste disposal

    J Electrost

    (2013)
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