Circular Economy Concepts
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Questions and Answers

What is a potential outcome of renting products to multiple users instead of selling them?

  • Reduced overall product functionality
  • Increased ownership of products
  • Maintaining value for material suppliers
  • Consumers willing to pay more for renting (correct)

What does the micro-level strategy in circular economy focus on?

  • Global decision-making processes
  • Individual products or business innovations (correct)
  • Supply chain management
  • Activities across businesses

Which of the following is a limitation to achieving circularity?

  • Low demand for new technologies
  • Global population increase (correct)
  • Availability of materials to recycle (correct)
  • High energy requirements for recycling (correct)

What does the term 'rebound effect' refer to?

<p>Increased consumption due to lower product prices (A)</p> Signup and view all the answers

What is one of the main limitations of Material Flow Analysis (MFA)?

<p>It only shows material stocks and flows. (B)</p> Signup and view all the answers

At the meso-level, which strategy is prioritized within the circular economy?

<p>Improving supply chains and industrial symbiosis (B)</p> Signup and view all the answers

What is a consequence of changing fashion and technology in relation to product desirability?

<p>Functional products may lose desirability (B)</p> Signup and view all the answers

Which type of uncertainty can be introduced when defining the system scope in MFA?

<p>Model uncertainty (C)</p> Signup and view all the answers

Which of the following strategies could help mitigate the constraints of circularity?

<p>Investing in biotic materials (B)</p> Signup and view all the answers

In the fridge scenario described, what is the total amount of groceries Martha, Stuart, and John buy in four weeks?

<p>36 kg (D)</p> Signup and view all the answers

Which approach is not typically involved in achieving circularity?

<p>Focusing solely on recycling efforts (A)</p> Signup and view all the answers

How does MFA deal with missing data when conducting an assessment?

<p>By using assumptions that must be justified. (B)</p> Signup and view all the answers

Which of the following accurately reflects a common stock-and-flow issue?

<p>Stock losses require compensation through additional purchases. (C)</p> Signup and view all the answers

What percentage of leftover food in the fridge goes bad each week according to the scenario?

<p>10% (A)</p> Signup and view all the answers

What is one way Martha, Stuart, and John could potentially reduce food waste?

<p>Only buy food that lasts longer. (A)</p> Signup and view all the answers

Which aspect is NOT a part of uncertainty in MFA?

<p>Technological advancements. (C)</p> Signup and view all the answers

What is the primary benefit of energy recovery from municipal solid waste (MSW)?

<p>It replaces some energy from fossil fuels. (B)</p> Signup and view all the answers

Which property of a waste fuel is most relevant for energy recovery processes?

<p>Lower heating value (LHV) (C)</p> Signup and view all the answers

What is the role of the boiler in the MSW incineration process?

<p>To boil water for steam generation. (D)</p> Signup and view all the answers

Which of the following methods yields fuels that are combusted to release heat?

<p>Anaerobic digestion (B)</p> Signup and view all the answers

What is the heat of vaporization of water typically considered in energy calculations?

<p>2.3 MJ/kg (D)</p> Signup and view all the answers

Why is the destruction of organic content in MSW significant in waste management?

<p>It minimizes waste volume. (A)</p> Signup and view all the answers

What additional information is necessary to calculate the higher heating value (HHV) of a fuel?

<p>The moisture content of the fuel (A)</p> Signup and view all the answers

What is a significant feature of gasification compared to combustion?

<p>It produces biogas as the main product. (A)</p> Signup and view all the answers

What does the term 'flow' represent in the context of material flow analysis?

<p>The amount of materials produced or processed in a specific period (A)</p> Signup and view all the answers

What best describes a 'stock' in material flow analysis?

<p>The mass of materials stored and accumulated over time (B)</p> Signup and view all the answers

Which of the following is an example of a transfer coefficient?

<p>The fraction of mixed waste that is converted into separate waste streams (D)</p> Signup and view all the answers

What is a key factor that influences the relationship between stocks and flows?

<p>The product lifetimes (A)</p> Signup and view all the answers

What is the purpose of a generic process diagram in material flow analysis?

<p>To serve as an initial framework for data collection processes (C)</p> Signup and view all the answers

How can the number of scrapped cars be inferred?

<p>By analyzing sales data and the average car lifetime (D)</p> Signup and view all the answers

What is a potential use for air pollution control residue (APCR)?

<p>To encapsulate APCR in concrete structures (D)</p> Signup and view all the answers

What impact do contaminants in APCR have on cement production?

<p>They can negatively affect both the process and the quality of cement (A)</p> Signup and view all the answers

What is the primary function of the induced-draft fan in the flue gas system?

<p>To draw cooled flue gas through air pollution control systems (B)</p> Signup and view all the answers

Which components are primarily contained in flue gas from municipal waste incineration?

<p>Unreacted nitrogen and excess oxygen (B)</p> Signup and view all the answers

What type of scrubbers are commonly used to react with acid gases in the flue gas stream?

<p>Semi-dry scrubbers with hydrated lime (C)</p> Signup and view all the answers

Which of the following technologies is used for reducing NOx in flue gas emissions?

<p>Selective catalytic reduction (SCR) (A)</p> Signup and view all the answers

What is the primary environmental concern associated with the emissions from incinerators?

<p>Toxicity from dioxins and furans (C)</p> Signup and view all the answers

What technology combination does the European Best Available Techniques (BAT) Reference Document for Waste Incineration refer to?

<p>408 technology combinations for emissions control (A)</p> Signup and view all the answers

Which type of filtration system is commonly used in modern incinerators for particulate removal?

<p>Fabric filters in a baghouse (A)</p> Signup and view all the answers

Why are modern incinerators designed to avoid the formation of dioxins and furans?

<p>They are highly toxic and carcinogenic (C)</p> Signup and view all the answers

What are the four impact categories examined in the study?

<p>Climate change, human health, ecosystem quality, resource depletion (A)</p> Signup and view all the answers

In which climate was the impact of building types NOT tested according to the study?

<p>Boston (A)</p> Signup and view all the answers

What is the primary reason supporting the sustainability of building renovation over new construction?

<p>It can take many years for new energy-efficient buildings to offset their construction's negative environmental impacts. (C)</p> Signup and view all the answers

Which UN Sustainable Development Goal is NOT directly supported by LCA in the construction sector?

<p>No poverty (SDG 1) (D)</p> Signup and view all the answers

How long can it take for a new energy-efficient building to overcome the environmental impacts of its construction?

<p>10 to 80 years (B)</p> Signup and view all the answers

What is the importance of examining multiple building types in different climates in this study?

<p>To evaluate how different conditions affect environmental impact. (C)</p> Signup and view all the answers

What common misconception about new energy-efficient buildings is highlighted in the study?

<p>They are immediately better for the environment than renovated buildings. (A)</p> Signup and view all the answers

Which statement about building renovation versus new construction is accurate based on the findings of the study?

<p>Renovating old buildings often has less overall environmental impact. (B)</p> Signup and view all the answers

Flashcards

Product-as-a-Service

Extending product functionality by renting instead of selling, appealing to consumers who prioritize access over ownership.

Micro-level Circularity

Strategies that address resource management at the individual product or business level, focusing on product design and business model innovation.

Meso-level Circularity

Strategies that focus on improving resource flows across multiple businesses, such as optimizing supply chains and promoting collaborative resource use.

Macro-level Circularity

Strategies that involve city, regional, national, or global level decision-making to monitor and support micro- and meso-level circular economy activities.

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Limits to Circularity: Global Growth

The challenge of balancing the benefits of circularity with the need for resource extraction to meet growing global consumption demands.

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Limits to Circularity: Material Flows

The difficulty of fully reusing and recycling all materials due to energy requirements, material dispersion, and limitations in technological efficiency.

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Rebound Effect

The phenomenon where waste prevention measures lead to lower product prices, potentially encouraging people to purchase more, thus negating the intended environmental benefits.

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Direct Rebound

The reduction in the cost of a product due to waste prevention, which can lead to increased demand and potentially counteract the initial environmental gains.

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Life Cycle Assessment (LCA)

A method for evaluating the environmental impacts of products and services throughout their entire life cycle, from raw material extraction to disposal.

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Green Building

A building that incorporates sustainable design principles and technologies to reduce its environmental impact.

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Building Renovation

The process of making an older building more energy-efficient and environmentally friendly.

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New Construction

The process of demolishing and rebuilding an older building with a new, more energy-efficient design.

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Payback Period

The amount of time it takes for a new energy-efficient building to compensate for the environmental impact of its construction through more efficient operations.

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United Nations Sustainable Development Goals (SDGs)

A group of 17 goals adopted by the United Nations in 2015 to address global challenges, including poverty, inequality, climate change, and resource depletion.

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Sustainable Cities (SDG 11)

The SDG that focuses on sustainable cities and communities, aiming to make cities more inclusive, safe, resilient, and sustainable.

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Responsible Consumption and Production (SDG 12)

The SDG that addresses responsible consumption and production patterns, aiming to reduce waste and promote sustainable lifestyles.

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Model Uncertainty in MFA

The uncertainty in a material flow analysis (MFA) arising from assumptions made when defining the system's boundaries and processes.

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Data Uncertainty in MFA

The uncertainty in a material flow analysis (MFA) caused by incomplete or unreliable data, requiring assumptions for missing information.

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Data Quality Assessment

Analyzing the quality of data used in a material flow analysis (MFA) to identify potential errors, inconsistencies, or limitations.

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MFA Limitation: No Impact Assessment

The limitation of MFA that prevents it from directly assessing the environmental or economic impact of a system or its components, focusing only on material flows.

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Stock and Flow Analysis Problem

In material flow analysis (MFA), a common problem where the balance between incoming and outgoing material flows within a defined system needs to be analyzed.

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System Boundary in MFA

The perimeter or boundary that defines the scope of a material flow analysis (MFA), including all processes and interactions within the system.

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Key Processes, Flows, and Stocks

Key processes, flows, and stocks that are essential for understanding the movement of materials within a system being analyzed by a material flow analysis (MFA).

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Product Lifetime in MFA

The time that a product remains in use before disposal or recycling, influencing the dynamics of material flows in a material flow analysis (MFA).

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Material Flow

The amount of a material that is produced, consumed, or released over a specific time period. Example: 7.8 million tons of cement produced in the UK per year.

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Material Stock

The total quantity of a material that exists at a specific point in time. Example: The total amount of cement in buildings across the UK.

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Transfer Coefficient

The proportion of a material that is transferred from one process stage to another. Example: The fraction of mixed waste that ends up as paper after being processed in a Material Recovery Facility (MRF).

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Product Lifetime

The duration a product is used before being discarded. Affects the relationship between stocks and flows as it determines how long materials remain in use.

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Process Diagram

A visual representation of the different stages of a process, showcasing material inputs, outputs, and transformations. Important for collecting data and understanding material flows.

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Data Gap Closure Techniques

Techniques used to fill in missing data gaps for material stocks and flows. Examples include using car sales data to estimate scrap car numbers or chemical equations to infer material transformation.

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Proxy Data

A similar process, geography, time period, or technology used to provide data when the exact desired data is unavailable. Requires scaling or averaging to be applicable.

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Coprocessing

Recycling or reusing a material in another process. Example: using air pollution control residues (APCR) from waste incineration as a component in cement production.

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Purpose of Energy Recovery and Controlled Disposal

Energy recovery aims to extract usable energy from waste, while controlled disposal focuses on safely and sustainably managing waste that cannot be recovered.

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MSW Incineration

MSW incineration involves burning municipal solid waste to generate energy. Pollution control measures, such as scrubbers and filters, are essential to reduce emissions.

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Anaerobic Digestion

Anaerobic digestion is a biological process where microorganisms break down organic matter in the absence of oxygen, producing biogas (primarily methane) and digestate.

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Landfill Design and Operation

Landfills are engineered sites for controlled disposal of waste. They involve layers of compacted waste, liners for containment, and gas collection systems for emission management.

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Landfill Closure

Landfill closure involves capping the landfill with a layer of soil and vegetation to prevent infiltration and promote environmental stability.

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Landfill Mining

Landfill mining involves extracting valuable materials from closed landfills, like metals and construction debris, for reuse.

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Other Disposal Methods

Alternatives to traditional landfill disposal include composting, pyrolysis, and plasma gasification, each with its own pros and cons in terms of energy recovery and environmental impact.

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Heating Values of Waste Fuels (HHV and LHV)

The higher heating value (HHV) of a fuel refers to the total heat released during combustion, including the heat of vaporization of water. The lower heating value (LHV) excludes this heat of vaporization, making it more relevant for energy recovery processes.

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How does a waste incinerator generate electricity?

High-pressure steam, created by heating water in tubes, drives a steam turbine, which in turn powers an electrical generator.

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What are the main components of flue gas from waste incineration?

Unreacted nitrogen and oxygen along with carbon dioxide (CO2) and water are major components of flue gas from municipal waste incinerators.

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What are dioxins and furans?

Dioxins and furans are toxic and carcinogenic substances that can be formed during the incineration process.

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How do modern incinerators limit dioxins and furans?

Modern incinerators are designed to minimize the formation of dioxins and furans by carefully controlling combustion temperatures and residence times.

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How are acid gases removed in flue gas cleaning?

Acid gases such as sulfur dioxide (SO2) and hydrogen chloride (HCl) are treated by spraying hydrated lime into the flue gas, which neutralizes the acids creating solid salts.

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How is mercury removed from flue gas?

Mercury, a heavy metal, often remains in the gas phase, and activated carbon can be used to remove it by adsorption.

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How are solid byproducts removed from flue gas?

Fly ash and other solid byproducts, including salts from acid gas scrubbing and activated carbon, are collected and separated from the flue gas.

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What type of filter is commonly used in modern incinerators for particulate removal?

Fabric filters are typically used in modern incinerators to remove particulate matter.

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Study Notes

Circular Economy

  • A circular economy is an economic system that aims to achieve sustainability goals through more efficient and circular use of materials.
  • It's defined as a model of production and consumption, involving sharing, leasing, reusing, repairing, refurbishing and recycling existing materials & products for as long as possible.
  • A circular economy replaces the linear take-make-dispose model with one where materials and products are used more intensively, for longer, and repeatedly.

Learning Objectives (Circular Economy)

  • Explain the idea, concepts, and principles of a circular economy.
  • Describe the main types and purposes of material loops.
  • Explain the major strategies for achieving a circular economy.
  • Explain how a transition to circularity may take place.
  • Reflect on challenges and limitations regarding circularity.

The Environment

  • Sustainable yield; the rate at which materials are extracted should not exceed the rate at which they regrow.
  • Stocks of non-renewable materials should be substituted with renewable materials in the long run.
  • Respect limits to the environmental pressures that ecosystems can endure.
  • Circular economy (CE) is tailored to addressing environmental pressures directly related to material use; it is not a comprehensive strategy for all manners of environmental protection.

Economy

  • In the long term, the economy should gain from the protection of the natural environment, because it critically depends on it for the provision of natural resources.
  • Cost savings may result from extended and repeated use of materials, reducing virgin material demand and input costs for businesses.
  • Price volatility of raw materials can be reduced.
  • Recycling and other circular activities reduce dependence on raw materials.
  • Businesses expect increasing demand for circular products and services (marketing advantages).

Society

  • A circular economy has the potential to address profound social impacts of production and consumption, although it is often promoted for its environmental and economic benefits.
  • The circular economy is relevant to the Sustainable Development Goals (SDGs).

Material Circularity

  • CE often distinguishes between two types of materials or 'nutrients': biotic and abiotic.
  • Narrower loops are generally preferred to wider loops because they tend to be more environmentally friendly and require less effort per unit of time.

Value Creation

  • The circular economy is driven by the observation that many common activities destroy material value.
  • Maintaining value in a circular economy can be achieved by maximizing added value.

Circular Strategies

  • Micro-level: Strategies that relate to individual products or businesses include product design and business model innovation.
  • Meso-level: Strategies that relate to cross-business activities, focus on improving supply chains and industrial symbiosis.
  • Macro-level: Strategies focused on decision-making at the city, region, national or global level to monitor and support micro- and meso-level activity.

Limits to Circularity

  • All circular-economy activity requires energy (for transport, cleaning, and disassembly).
  • Many materials are not available to be circled back into the economy and 100% efficient circulation of materials is rarely possible.
  • Global growth in consumption, and changing fashion and technology pose challenges.
  • The rebound effect exists: when waste prevention reduces the cost of a product, people often buy more, leading to further environmental impact.

Life Cycle Assessment (LCA)

  • LCA is a powerful tool used to assess the environmental impact of products, processes, and services throughout their entire life cycle.
  • The course focuses on LCA of products and processes related to buildings, infrastructure, and the built environment in general.
  • Environmental impact includes a wide range of negative effects (stressors).
  • Life cycle thinking is a crucial approach for LCA, based on three key principles: Systems perspective, Long-term view, and Interdisciplinary approach.
  • A YouTube video explains how to map out the life cycle of a product.

Environmental Footprint

  • Environmental footprint measures the impact of buildings and infrastructure on the environment.
  • Types of environmental footprint include Water Footprint, Carbon Footprint (Climate Change Footprint), Resource Footprint, Atmospheric Footprint, Waste Footprint, and Biodiversity Footprint (Ecological Footprint).

LCA for Sustainable Construction

  • LCA helps with key decisions about building design, material selection, and construction methods.
  • LCA helps with sustainable infrastructure planning, urban development and impact assessment.
  • LCA can help mitigate climate change, reduce water pollution and reduce resource depletion.

Benefits of LCA

  • LCA enables the construction sector to contribute to UN Sustainable Development Goals (SDGs).
  • LCA enables life cycle design.
  • LCA practical applications include Environmental Product Declarations (EPDs), which provide transparent and comparable information about the environmental performance of products over their life cycle, including resource depletion, global warming potential, energy consumption, water consumption, and emissions to air, water, and soil.
  • LEED awards points for using building materials with verified EPDs.

LCA in Practice

  • Examining impact categories (climate change, human health, ecosystem quality, resource depletion) for different building types and climates; helps determine the environmental impacts of building renovation vs. new construction.
  • Examples of LCA application are the National Trust for Historic Preservation comparing new and renovated building's impact on the environment.

Hazardous Waste and Risk Management

  • This involves careful handling, specialized containers & transport, and licensed disposal facilities to manage hazardous waste.
  • Specific regulations (e.g., EPA in the US) must be strictly adhered to for liability and risk management purposes.
  • Proper industrial waste management can be expensive.

Waste Collection and Treatment

  • The purpose and concept of waste treatment (physical, physicochemical, biological & thermal) is covered.
  • The technological basis of widely applied waste treatments include topics like: different treatment processes, the Waste Hierarchy (reduce, reuse, recycle, recover, dispose), global waste statistics, and zero-waste philosophies.
  • Main environmental impacts are discussed for treatment technologies.

Assessment Methods

  • Main purposes of conducting an impact assessment include material flow analysis (MFA) and lifecycle assessment (LCA).
  • MFA is a systematic assessment of the flows and stocks of materials with a defined system scope/boundary, Input – Output = Stock change.
  • The process diagram is an iterative data-collection process. Methods to address data gaps are presented (e.g., using stock dynamics, stoichiometry, and proxies).
  • Various sources of uncertainty (gaps in data sources) are outlined in MFA, including aspects of data quality. Examples of MFA studies and their importance are provided, e.g., on mapping current flows and recycling potential of paper lifecycle in the EU economy.

Energy Recovery and Disposal

  • The purpose of energy recovery and controlled disposal, is to understand the process and main aspects of anaerobic digestion, MSW incineration, landfill design, operation, closure and landfill mining and to describe the various final disposal methods.
  • Energy recovery has the additional benefit of replacing some fossil fuels with energy recovered from waste and various waste types as fuel are described in comparison with coal and natural gas
  • Detailed aspects of flue gas cleaning during incineration are provided, covering the common technologies employed for acid gases, NOx and fly ash removal.

Waste Recycling

  • Purpose, concept, types, process, challenges, limitations and benefits of recycling in material industries, and economic motivations are discussed.
  • The concept of recycling is the reprocessing of waste into a feedstock for making new materials/products.
  • Recycling consists of collection, separation, cleaning/processing into a secondary feedstock.
  • Recycling can reduce impacts from extraction of primary materials, reducing energy, transport and emissions, but may require more water or chemicals, plus some differences in production technology.
  • Recycling and product lifetimes are discussed regarding the completeness of the recycle process.
  • Cases from Jordan and Lebanon regarding waste management efficiency are discussed.

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Description

This quiz explores key concepts and strategies related to the circular economy, including micro and meso-level approaches, limitations to achieving circularity, and the impact of consumer behavior. Test your understanding of terms like rebound effect and material flow analysis.

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