Waste to Energy in the Age of the Circular Economy

Best Practice Handbook

• Publisher: Asian Development Bank
• Year: 2020
• ISBN:
  9789292624811
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

This handbook features best practices for integrating waste to energy and related technologies into the operations of various industries. It discusses current technologies, presents a conceptual example of municipal solid waste planning, and provides commentary on waste-to-energy initiatives. The importance of appropriate infrastructure as well as flexibility and openness to technologies and business models is emphasized. The handbook—and its complementary compendium of 18 projects—aim to support the efforts of developing countries in Asia and the Pacific to deploy and scale up technologies relevant to the circular economy.

1  INTRODUCTION

In 2016, the world generated an estimated 2.01 billion tons of municipal waste and this is projected to reach 3.4 billion tons by 2050. Around 44% of global waste are categorized as food and green waste while the other 38% are dry recyclables such as paper, cardboard, plastic, glass, and metal. The other 18% includes rubber and leather, wood, and others. It is expected that the amount of waste being generated will continue to increase due to economic development, population growth, and degree of urbanization. However, at least 33% of the waste is openly dumped and not managed in an environmentally safe manner. Especially in low-income countries, about 93% of the waste is burned or dumped on road easements, open lands, or waterways.¹

However, waste cannot be dealt with in isolation in a sustainable energy ecosystem and the fast-developing circular economy future. The source, composition, and value of waste streams vary geographically and will continue to change with the region’s economic growth, policies, and regulations; education; and technological advancement.

In particular, waste to energy (WtE) has a role to play in achieving the transformation to a sustainable energy ecosystem as a renewable energy source to reduce greenhouse gas (GHG) emissions, a clean demand response option, a design consideration of eco-industrial parks, and sometimes the only option for end-of-life waste treatment.

The Asian Development Bank (ADB) has recognized the importance of WtE in the Asia and Pacific region and has facilitated and supported projects for more than 12 years. The first initiative started as early as 2007 with the approval of the project, Development of Biomass Power Generation in Rural Areas, in the People’s Republic of China (PRC). As of December 2018, a total of 27 WtE projects have been proposed, of which six are active and three already approved. With nearly half of the projects in the proposed stage, there is great potential of WtE in the ADB portfolio in the coming years.

ADB is continuing to support its developing member countries (DMCs) through assistance in de-risking and managing private–public partnerships in the WtE sector, investments and/or loans to emerging developers in DMC markets, and inclusion of WtE-related projects in its sovereign operations.

WtE is often considered as a costly option for waste disposal and energy generation when compared with other fossil fuel-powered generation alternatives. There is a disconnect as the environmental and social benefits of WtE are not valued in comparison with more established renewable alternatives such as wind and solar energy. The business models for WtE are usually more complicated than established alternatives. Considerations such as availability and steady supply of feedstock, choice of technology, and appropriate policy framework, among others, should be given extra consideration in WtE development.

Electrical energy accounts for 25% of the total revenues in waste-to-energy plants in the European Union. The remainder is for environmental treatment fee (gate fee) and the sale of ancillary products including heat, bottom ash, and slag. The current models being proposed in ADB's developing member countries is closer to 50% of revenues from electrical energy.

Thought leadership on human civilization provides a framework to consider alternate approaches to waste-related problems, namely the circular economy.

The circular economy describes emerging policies, business models, investment foci, and community behavior on less pollutive, resource-prudent, and efficient activities underpinning our global civilization. These concepts can be simplified to explain the differences between our current throwaway (linear) culture, the recycling economy, and the circular economy.

Figure 1: The Circular Economy Simplified

Source: Asian Development Bank internal training material.

The circular economy will require extensive product and business process redesign. Major multinational companies are playing catch up due to consumer demand. DMCs are currently transitioning from the linear (throwaway) economy to a recycling economy. The circular economy is infiltrating the recycling economy and will become the dominant economic model over the coming decade(s).

This means conversion from the current linear thinking model with large set-piece infrastructure to a distributed model using the circular economy thinking. By creating smaller circular steps closer to the source of waste generation, more expensive end- of-life solutions can be rightsized due to higher resource recovery rates (from 10% moving closer to 80% recovery).

This Waste to Energy in the Age of the Circular Economy: Best Practice Handbook has been prepared to serve as a reference guide to ADB staff and consultants, as well as ADB DMCs. The objectives are to help the reader understand waste as an evolving resource, the approach to develop a strategy, and if WtE is elected as an appropriate next step, assist the reader in reviewing technology options. This handbook focuses on various waste stream including municipal solid waste (MSW), and industrial and agricultural waste. Hazardous waste may be further discussed in future ADB handbooks.

A collection of 18 case studies and a summary of 11 emerging WtE technologies are detailed in the accompanying compendium. The emerging technologies are provided at high level, knowing that new technologies are being developed and it can take time to move the new technology to commercialization. As much as possible, concepts are presented in simple terms to achieve a thorough understanding of the subject and to encourage access by a wider audience.

The handbook is divided into different sections:

(i)An overview of waste:

a. waste section describes various wastes, their composition, and characteristics;

b. the WtE section discusses its various components such as feedstock, energy conversion technologies, applications, and outputs and residues.

(ii)An overview of WtE technologies

(iii)A WtE planning and strategies section highlights the 12 pathways to waste management, key considerations, and processes in developing WtE projects.

(iv)A hypothetical case is presented in the Waste Infrastructure and Planning Example section providing key proposals for a WtE project.

(v)The conclusion section condenses the findings of the report and how it can be related to ADB’s DMCs given their waste management practices and WtE development potential.

The handbook also includes a compendium of existing project case studies and emerging technologies:

(i)Detailed and actual WtE project examples section includes existing projects using simple to complex technologies with varying degrees of implementation, i.e., from village to industry levels are compiled in one section of this report. Each case study includes the technology used and narrates the lessons learned while implementing the individual projects.

(ii)A high-level summary of emerging technologies and their current stage of maturity accordingly to the technology readiness level (TRL) assessment.

2 WHAT IS WASTE?

Waste is anything we want to get rid of. There are many definitions of waste. The United Nations Statistics Division defines waste as materials that are not prime products (that is, products produced for the market) for which the generator has no further use in terms of his/her own purposes of production, transformation, or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Not included in this definition are residuals recycled or reused at the place of generation.²

TYPES OF WASTE

There are different types of wastes³ and they can be classified according to their state, i.e., solid, liquid, and air. Solid waste can be both organic and inorganic. Mud, sludge, effluents, and other liquid forms of waste need special means of collection and transportation and commonly these materials can be toxic and harmful to the environment. Effluents include sewage and wastewater from industries such as agricultural processing and many types of manufacturing. Gaseous waste should not be confused with air pollution. This handbook focuses on common forms of waste where energy or value can be extracted, not only MSW. Other waste streams may be reviewed further in future handbooks.

Municipal Solid Waste

MSW can be both organic (e.g., food waste, paper and rubber products, fabric, plant matter, plastics) and inorganic (e.g., glass, metal, construction debris). MSW is generated at households, offices, shops, schools, hospitals, hotels, and other institutions. The major components are food, paper, rags, metal, tires, construction debris, glass, and hazardous waste such as light bulbs, batteries, chemicals, etc. Majority of the MSW goes to landfill in jurisdictions where a collection system is developed and implemented. Municipal waste can be further classified into different types depending on their point of generation.

(i)Household waste is generated in the operation of household activities.

(ii)Commercial waste consists of waste from areas where business or trade is conducted. This may include business relating to sports, recreation, education, or entertainment excluding household, agricultural, and industrial sectors.

(iii)Construction and demolition waste is generated from the building industry. The debris range from insulation, electrical wiring, rebar, wood, concrete, and bricks.

(iv)Hazardous waste contains scheduled items such as lead, asbestos, or other hazardous materials. These are often intermingled with other types of waste. It requires separate handling and disposal. (Please note that detailed technical information on hazardous and medical waste handling and disposal are not foci of this handbook).

(v)Inert waste includes materials which do not chemically or biologically decompose such as metal, sand, and concrete, among others.

If all MSW is monitored, sorted, and categorized, humanity could recover more energy and recycle more materials. Food and green waste is the largest waste category, which constitute 44% of the global waste. Other recyclables, e.g., paper, cardboard, plastic, glass and metal, follow at 38% (Figure 2). The composition varies by level of income; generally, the percentage of organic matter decreases as the level of income rises among countries (footnote 1).

Figure 2: Composition of Municipal Solid Waste

Source: World Bank. 2018. What a Waste 2.0: A Global Snapshot of Solid Waste Management to 2050.

Industrial Solid and Liquid Waste

Waste under this category includes paper, waste from food processing, packaging materials, paper, glass, stones, ceramics, metals, rubber, plastics, leather, wood, cloth, abrasives solvents, resins, paints, and oils.

Agricultural Waste and Residues

Agricultural waste and residues are those are left during agricultural production. Some of the wastes are used as fertilizer while a substantial amount remains unused. Agricultural wastes are often disposed through uncontrolled burning in the fields or dumped in the open area or in waterways. This is a major contributor to air pollution in many countries. This type of waste is discussed thoroughly in the next section.

WASTE DISPOSAL

Globally, a large percentage of waste (40%) goes to landfill and about 19% is either recycled and composted. An estimated 11% goes through modern thermal treatment. However, around 33% of waste is still openly dumped especially among low-income countries of which about 93% practices burning and dumping. Waste is dumped in open land, roads, or waterways. Meanwhile, only 2% of waste in high-income countries is openly dumped.

The development of engineered and/or sanitary landfill is a first step of progression from open dumping toward sustainable waste management. About 54% and 3% of waste are disposed in suitable landfills among middle-income and low-income countries, respectively. High-income countries, on the other hand, place greater attention on materials recovery through recycling and composting. The typical waste disposal methods within this income category are through landfill (39%), recycling (29%), thermal treatment (22%), composting (6%), and open dumping (2%).

WASTE MANAGEMENT PRACTICES

This section describes general waste management practices for solid waste, wastewater, and radioactive waste.

Municipal Solid Waste

Waste management practices vary based on the country, location, and type of waste being collected. Waste collection usually constitutes the major solid waste management costs in cities and municipalities (footnote 1). Household waste is disposed of in plastic bags, old cans, and baskets for curbside/gate collection; waste cans collected from designated locations for community dumping in bins, dumpsters, or simply piled up by the roadside. In some cases, skip bins or communal bins are placed near markets or populated centers.

In high-income industrialized countries, waste collection rate is almost 100%. Compactor trucks and highly mechanized vehicles and transfer stations are c...