Elsevier

Waste Management

Volume 69, November 2017, Pages 407-422
Waste Management

A review on technological options of waste to energy for effective management of municipal solid waste

https://doi.org/10.1016/j.wasman.2017.08.046Get rights and content

Highlights

  • The current status, options and challenges of WTE techniques were analysed.

  • Incineration is the most widely used WTE technology in the developed countries.

  • Landfilling is the most common practice of MSWM in developing countries.

  • Approximately 50 million tonnes of methane is emitted annually from landfills.

  • WTE will ensure both the energy security and environmental protection.

Abstract

Approximately one-fourth population across the world rely on traditional fuels (kerosene, natural gas, biomass residue, firewood, coal, animal dung, etc.) for domestic use despite significant socioeconomic and technological development. Fossil fuel reserves are being exploited at a very fast rate to meet the increasing energy demands, so there is a need to find alternative sources of energy before all the fossil fuel reserves are depleted. Waste to energy (WTE) can be considered as a potential alternative source of energy, which is economically viable and environmentally sustainable. The present study reviewed the current global scenario of WTE technological options (incineration, pyrolysis, gasification, anaerobic digestion, and landfilling with gas recovery) for effective energy recovery and the challenges faced by developed and developing countries. This review will provide a framework for evaluating WTE technological options based on case studies of developed and developing countries. Unsanitary landfilling is the most commonly practiced waste disposal option in the developing countries. However, developed countries have realised the potential of WTE technologies for effective municipal solid waste management (MSWM). This review will help the policy makers and the implementing authorities involved in MSWM to understand the current status, challenges and barriers for effective management of municipal solid waste. This review concluded WTE as a potential renewable source of energy, which will partly meet the energy demand and ensure effective MSWM.

Introduction

Currently fossil fuels are the most reliable sources of energy, meeting almost 84% of the global energy demand (Shafiee and Topal, 2009). It is the time to realise the potential of waste to energy (WTE) as an option for sustainable solid waste management and as one of the most significant future renewable energy sources, which is economically viable and environmentally sustainable (Bajić et al., 2015, Kalyani and Pandey, 2014, Stehlik, 2009). Ali et al. (2012) concluded that WTE is not only sustainable waste management solution, but also an economically feasible, especially for developed countries. Baran et al. (2016) reported that energy recovery from waste incineration (one of the WTE technologies) is an integral part of environmentally sustainable waste management strategy. However, Yay (2015) did not find incineration as always economically sustainable due to its high operational and maintenance cost. WTE is a way to recover the energy from waste materials in the form of useable heat, electricity (by passing gas or steam through turbine), or fuel (Zhao et al., 2016). WTE technologies are now considered as the most suitable options for solving the waste related problems.

This paper aims to investigate municipal solid waste (MSW) as a potential renewable energy source. The present paper reviewed the available literatures on current global scenario of WTE technologies, necessary requirements for effective energy recovery and environmental impacts of different waste disposal techniques. The WTE technologies adopted in developed countries have been assessed to identify the challenges and barriers for effective implementation of WTE technologies in developing countries. In this review, 155 articles published in reputed journals, technical reports, and books related to WTE technologies (from year 1995 to 2017) were selected. More than 70% of the selected references were from year 2010 to 2017. For performing the review, a systematic approach was followed in which different aspects of WTE were identified. The identified aspects are: (i) the present status of WTE at global level, (ii) need of WTE, (iii) generation, characteristics and compositional requirements for effective energy recovery, (iv) WTE technological options and challenges associated with them in developed and developing countries, and (v) environmental and health impacts of WTE facilities. The previously published literatures and reports were selected and categorised based on these identified aspects. This study will provide a source of scientific information and analysed gap in the field of WTE to the scientific audience and waste management planners.

Global urban population is increasing at a fast rate (1.5%) than that of the total population (Ouda et al., 2016). At present, more than half of the world population live in urban areas, so the global escalation of MSW generation is mainly due to the population growth, urbanisation and economic development (Kumar and Samadder (2017)). Presently, the per capita MSW generation rate in developed countries is more than that of the developing countries, because generation rate depends on economic and social prosperity of a country. It was estimated that in coming decades the developing countries of Asia and other parts of the world will match the MSW generation rate of developed countries (Fazeli et al., 2016). Slowly, the people of developing countries are adapting lifestyle of developed nations due to globalisation, resulting in generation of large quantities of wastes. Thus, the escalation in MSW generation rate is mainly due to changing food habits, consumption pattern and living standards of the urban population (Khan et al., 2016).

Many researchers have reported that recycling is more preferred option than energy recovery (Tan et al., 2014, Ouda et al., 2016). It was observed from previous findings that the countries, which exercised high rate of energy recovery from wastes had appreciable rates of recycling, whereas, for the developing countries where landfilling is the most prevalent waste management option, recycling rates were low (Achillas et al., 2011). Arafat et al. (2015) reported the average recoverable energy contents (in terms of electrical energy efficiency) for different components of MSW using different WTE technologies (Fig. 1). From Fig. 1, it is evident that, anaerobic digestion is the best suited WTE option for food and yard wastes, whereas, gasification is the best WTE option for treating plastic wastes. Incineration remains an attractive option amongst all the waste streams (as specified by Arafat et al., 2015), as it can be used for energy recovery from all the reported waste streams. However, other types of wastes such as inert, metals, glass, etc., were not considered in that study.

A major challenge, however, remains in identifying better WTE technologies. There are some social oppositions for development of the WTE facilities due to potentially toxic emissions (Zhao et al., 2016). On the other hand, some characteristics of WTE facilities are also not favourable, such as high costs and difficulties in arranging fund (Zhang et al., 2010). However, one of the major problems of WTE facilities is the protests from local communities, especially in developing countries with high population density (Ren et al., 2016, Kalyani and Pandey, 2014). Thus, for successful implementation of any WTE facility, its acceptance by the local community is important (Kikuchi and Gerardo, 2009). Developed countries have realised the potential of WTE options and have started implementing it for effective waste management successfully.

The world population was 3 billion in 1960, which has increased to 7 billion in 2011 and it is expected to reach 8.1 billion by 2025 (FAO, 2013). The dramatic increase in global population coupled with economic development had led to rapid urbanisation and industrialisation, which changed the consumption pattern of the population that ultimately lead to the proliferation of MSW at an alarming rate. Many countries started adopting the WTE technologies for effective management of huge quantity of waste to produce energy. An estimate by the International Renewable Energy Agency, showed that the world has a potential of generating approximately 13 Giga Watt of energy from WTE sector alone (IRENA, 2016). The WTE technologies have been greatly modernised and prioritised especially in the developed nations. In 2012, USA alone generated 14.5 million MWh of electricity from 84 WTE facilities (ERC, 2014). Incineration is the most widely used WTE option in populous countries like China (Liu et al., 2006), which had around 160 incineration plants in operation till 2010 (Lianghu et al., 2014). There were about 1900 waste incineration plants in Japan, out of which, only 190 incineration plants were equipped with power generation facilities (Montejo et al., 2011), but Bajić et al. (2015) reported that only 102 waste incineration plants were in operation for electricity generation in Japan. Japan is followed by the European Union (mainly France), and then the United States in terms of quantity of waste incinerated (Montejo et al., 2011). Out of the total quantity of MSW generated, 74% in Japan, 54% in Denmark, 50% in both Switzerland and Sweden are incinerated (The World Bank, 2012, Psomopoulos et al., 2009). Italy installed many anaerobic co-digestion plants with capacity ranging from 50 kW to 1 MW (Pantaleo et al., 2013). The International Solid Waste Association (ISWA) reported that, globally more than 130 million tonnes of MSW per year (10% of the total generated waste globally) is treated to generate electricity (ISWA, 2012). A study carried out by Earth Engineering Center of Columbia University in 2013 regarding the percentage of waste recycled/composted, landfilled or diverted towards WTE facility across different countries found that most of the developed countries prefer to use environmentally sustainable techniques such as recycling/composting and WTE for the management of their generated wastes (ERC, 2014). The European countries such as Netherlands, Belgium, Denmark, Germany, Austria, Sweden and Switzerland divert most of their wastes from landfill for recycling and composting facilities (Defra, 2013). In Asian countries, Singapore recycles 44% of their generated wastes, while in other countries (mostly developing), typically 8–11% wastes are recycled (Ngoc and Schnitzer, 2009). It has been reported that, some cities such as Hanoi, achieved recycling rate of 20–30% (Velis et al., 2012). Many developing countries such as India, Vietnam, and Malaysia have started recovering energy from organic wastes, but at smaller scale. Nguyen et al. (2014) estimated that, food waste alone could meet up to 4.1% of Vietnam’s electricity demand if converted into biogas using anaerobic digestion process. The potential of WTE technologies has not yet been recognised by many of the developing countries.

At the end of this century, the global energy demand is expected to be about six times more than that of the current demand (Kothari et al., 2010). The current available energy supply is much lower than the actual energy required for consumption in many of the developing countries. At present, one of the primary sources of energy throughout the world is fossil fuels that meet the demand of approximately 84% of the total electricity generation (Ouda et al., 2016). Due to rapid depletion of fossil fuel reserves, the world needs alternative sources of energy such as WTE for mitigating the future energy crisis (Charters, 2001). The problem of disposal of huge quantity of generated MSW and the requirement of reliable source of renewable energy are common in many developing countries. MSW causes serious environmental pollution, thus its use as a potential renewable energy source would serve the purpose of meeting increased energy demand as well as waste disposal.

Technological advancement, improved pollution control systems, governmental incentives and stringent regulations have made WTE technology a potential alternative, especially for the developed countries. It not only provides a source of energy, but also reduces the potential harmful impacts of waste on the environment. If 1 tonne of MSW is incinerated for electricity generation instead of landfilling (without gas recovery), then 1.3 tonnes of CO2 equivalent emissions can be avoided if equivalent CO2 emissions from fossil fuel based power plants are also considered to generate the same amount of electricity (ASME, 2008). The waste incineration plants with energy recovery facility run with pre-treated MSW as a primary fuel have slightly low net carbon emission factor (0.04–0.14 kg/MJ) compared to fossil fuel based power plants (Patumsawad and Cliffe, 2002). The restrictions on landfill sites for MSW disposal and increase in public awareness on environmental impacts of MSW have forced the governments to find more effective ways of MSW disposal (Zhao et al., 2016). The land requirement for WTE facilities is much less than that of landfill facilities for handling same quantity of waste (Jamasb and Nepal, 2010). WTE plant processing 1 million tonnes of wastes per year has an average working life of more than 30 years and requires less than 100,000 m2 of land, whereas a landfill for 30 million tonnes of MSW requires a land of 300,000 m2.

Section snippets

Waste generation, characteristics and composition

Before selection and implementation of WTE technologies, it is necessary to know the amount of waste generated its characteristics and compositions. According to the World Bank report 2012, the global MSW generation rate was 1.3 billion tonnes per year with average generation rate of 1.2 kg/c/d. The generation rate of MSW is expected to reach 2.2 billion tonnes per year by 2025 and 4.2 billion tonnes per year by 2050 (Hoornweg and Bhada-Tata, 2012). The solid waste generation rate is directly

Heating values of municipal solid waste

One of the important parameters for determination of energy content of MSW is the heating value or the calorific value. Therefore, it is necessary to have reliable and accurate heating value data of MSW components for efficient design and successful operation and maintenance of a WTE facility (Shi et al., 2016). A major problem is the inconsistencies in reporting the energy content of MSW. Generally, the reported studies described the energy content in terms of higher heating value (HHV), lower

Waste to energy options

The aims of any waste management system are material and energy recovery, followed by disposal of the residues. But, an optimal choice for a waste processing technology is not only subject to economic requirements, energy recovery or waste destruction ability, but also to look for environmental regulatory compliance requirements of the concerned area. Therefore, it is necessary to select the best available technology for waste processing, which fulfils all the required criteria for a successful

Energy recovery potential and economics of WTE technologies

At present, China generates about 300 million tonnes of waste annually (World Energy Resources, 2016) and the waste contains high proportion of food waste of low calorific value and high moisture content similar to that of other developing countries. Therefore, the conventional incineration plants used in developed countries are expected to perform poorly in such conditions. Thus, China has developed new circulating fluidised bed based incineration plants to counter this problem and currently

Environmental and health impacts

MSW incineration may result in air pollution (due to the emissions of SOx, NOx, COx, dioxin and furans), soil and water pollution (due to the presence of heavy metals in the fly ash and bottom ash). But there has been a significant development in the pollution control technologies and energy recovery systems for incineration, which made it an attractive MSWM option (Damgaard et al., 2010). The use of air pollution control equipment in incineration plants is mainly to capture particulate

Impact on climate change

The studies on the impact of WTE plants and other MSWM options on climate change are largely based on developed countries (UNEP, 2010). Climate change is a global problem that requires a collective efforts from all the nations for its mitigation. It is vital to implement technologies that can reduce greenhouse gas (GHG) emissions and mitigate the climate change created by the production and consumption of energy generated from conventional means (IPCC, 2007). MSW has been considered as the

Conclusions

This paper presents a comprehensive review of different WTE technologies used for energy recovery. An attempt was made to summarise the current scenario of WTE sectors across the world. The MSW can be considered as one of the most potential renewable energy sources if WTE technologies are adopted that will not only reduce the dependency on conventional energy sources to meet the ever-increasing energy demand, but also reduce the problem of MSWM. After reviewing all the available WTE

Acknowledgements

The authors acknowledge the support provided by the Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad for carrying out the research work.

References (155)

  • L. Appels et al.

    Anaerobic digestion in global bio-energy production: potential and research challenges

    Renew. Sustain. Energy Rev.

    (2011)
  • C. Aracil et al.

    Proving the climate benefit in the production of biofuels from municipal solid waste refuse in Europe

    J. Clean. Prod.

    (2017)
  • H.A. Arafat et al.

    Environmental performance and energy recovery potential of five processes for municipal solid waste treatment

    J. Clean. Prod.

    (2015)
  • H.A. Arafat et al.

    Modeling and comparative assessment of municipal solid waste gasification for energy production

    Waste Manage.

    (2013)
  • P. Baggio et al.

    Energy and environmental analysis of an innovative system based on municipal solid waste (MSW) pyrolysis and combined cycle

    Appl. Therm. Eng.

    (2008)
  • B.Z. Bajić et al.

    Waste-to-energy status in Serbia

    Renew. Sustain. Energy Rev.

    (2015)
  • B. Baran et al.

    Utilization of energy from waste potential in Turkey as distributed secondary renewable energy source

    Renew. Energy

    (2016)
  • J.D. Browne et al.

    Assessing the variability in biomethane production from the organic fraction of municipal solid waste in batch and continuous operation

    Appl. Energy

    (2014)
  • P.H. Brunner et al.

    Waste to energy–key element for sustainable waste management

    Waste Manage.

    (2015)
  • W.W.S. Charters

    Developing markets for renewable energy technologies

    Renew. Energy

    (2001)
  • Y. Chen et al.

    Inhibition of anaerobic digestion process: a review

    Biores. Technol.

    (2008)
  • H. Cheng et al.

    Municipal solid waste (MSW) as a renewable source of energy: Current and future practices in China

    Biores. Technol.

    (2010)
  • F. Cherubini et al.

    Life cycle assessment (LCA) of waste management strategies: landfilling, sorting plant and incineration

    Energy

    (2009)
  • N. Curry et al.

    Biogas prediction and design of a food waste to energy system for the urban environment

    Renew. Energy

    (2012)
  • A. Damgaard et al.

    Life-cycle-assessment of the historical development of air pollution control and energy recovery in waste incineration

    Waste Manage.

    (2010)
  • A. Emery et al.

    Environmental and economic modelling: a case study of municipal solid waste management scenarios in Wales

    Resour. Conserv. Recycl.

    (2007)
  • A. Fazeli et al.

    Malaysia' s stand on municipal solid waste conversion to energy: a review

    Renew. Sustain. Energy Rev.

    (2016)
  • M.S. Fountoulakis et al.

    Potential for methane production from typical Mediterranean agro-industrial by-products

    Biomass Bioenerg.

    (2008)
  • T. Fruergaard et al.

    Optimal utilization of waste-to-energy in an LCA perspective

    Waste Manage.

    (2011)
  • L. Giusti

    A review of waste management practices and their impact on human health

    Waste Manage.

    (2009)
  • X. Gomez et al.

    Anaerobic co-digestion of primary sludge and the fruit and vegetable fraction of the municipal solid wastes: conditions for mixing and evaluation of the organic loading rate

    Renew. Energy

    (2006)
  • J.F. González et al.

    Pyrolysis of automobile tyre waste. Influence of operating variables and kinetics study

    J. Anal. Appl. Pyrol.

    (2001)
  • M.R. Haider et al.

    Effect of mixing ratio of food waste and rice husk co-digestion and substrate to inoculum ratio on biogas production

    Biores. Technol.

    (2015)
  • S.S. Hla et al.

    Characterisation of chemical composition and energy content of green waste and municipal solid waste from Greater Brisbane, Australia

    Waste Manage.

    (2015)
  • G. Ionescu et al.

    Integrated municipal solid waste scenario model using advanced pre-treatment and waste to energy processes

    Energy Convers. Manage.

    (2013)
  • T. Jamasb et al.

    Issues and options in waste management: a social cost–benefit analysis of waste-to-energy in the UK

    Resour. Conserv. Recycl.

    (2010)
  • H.K. Jeswani et al.

    Assessing the environmental sustainability of energy recovery from municipal solid waste in the UK

    Waste Manage.

    (2016)
  • A. Johari et al.

    Economic and environmental benefits of landfill gas from municipal solid waste in Malaysia

    Renew. Sustain. Energy Rev.

    (2012)
  • K.A. Kalyani et al.

    Waste to energy status in India: a short review

    Renew. Sustain. Energy Rev.

    (2014)
  • A. Karagiannidis et al.

    A multi-criteria ranking of different technologies for the anaerobic digestion for energy recovery of the organic fraction of municipal solid wastes

    Biores. Technol.

    (2009)
  • S. Kathiravale et al.

    Modeling the heating value of municipal solid waste

    Fuel

    (2003)
  • S. Kathirvale et al.

    Energy potential from municipal solid waste in Malaysia

    Renew. Energy

    (2004)
  • D. Khan et al.

    Impact of socioeconomic status on municipal solid waste generation rate

    Waste Manage.

    (2016)
  • R. Kikuchi et al.

    More than a decade of conflict between hazardous waste management and public resistance: a case study of NIMBY syndrome in Souselas (Portugal)

    J. Hazard. Mater.

    (2009)
  • K. Komemoto et al.

    Effect of temperature on VFA’s and biogas production in anaerobic solubilization of food waste

    Waste Manage.

    (2009)
  • D. Komilis et al.

    Revisiting the elemental composition and the calorific value of the organic fraction of municipal solid wastes

    Waste Manage.

    (2012)
  • D. Komilis et al.

    Effect of organic matter and moisture on the calorific value of solid wastes: an update of the Tanner diagram

    Waste Manage.

    (2014)
  • M.S. Korai et al.

    Optimization of waste to energy routes through biochemical and thermochemical treatment options of municipal solid waste in Hyderabad, Pakistan

    Energy Convers. Manage.

    (2016)
  • R. Kothari et al.

    Waste-to-energy: A way from renewable energy sources to sustainable development

    Renew. Sustain. Energy Rev.

    (2010)
  • A. Kumar et al.

    An empirical model for prediction of household solid waste generation rate – a case study of Dhanbad, India

    Waste Manage.

    (2017)
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