WASCON 2015 – Santander, 10–12 June 2015 1

Complex Value Optimization for Resource Recovery

(CVORR): A Tool for an Evidence-based Pathway to

Circular Economy

Maria CORONADO, Eleni IACOVIDOU, Jonathan BUSCH, Phil PURNELL, Costas A.

VELIS*

University of Leeds, Faculty of Engineering, School of Civil Engineering

* Corresponding Author: Costas Velis: School of Civil Engineering Room 304. University of Leeds, Woodhouse

Lane, LS2 9JT Leeds, UK. Email: c.velis@leeds.ac.uk

Abstract

In established linear systems the values of materials are often lost or dissipated into waste ending up in

landfills. Europe is proposing a range of measures to accelerate the transition from these linear

systems to a more circular economy along the full supply chain. This requires new ways of looking at

traditional industrial systems and materials flows, using a systems approach and taking into account

multidimensional aspects of value embedded into products, items, components and materials, before

they become waste and during their processing for value extraction. Here, we introduce a new

methodological framework that combines life cycle inventories with the flow of materials capable of

accounting for multiple values (economic, social, environmental and technical) of materials within

resource recovery systems. This framework will allow for a whole system analysis of the complex

values in waste, considering internal loop, system boundaries, and uncertainty, while extending

significantly in the socioeconomic evaluation of the recourse recovery. Complex resource recovery

implications of alternative scenarios for product/waste systems will be systematically assessed,

including potential changes to the system upstream and downstream of waste generation point. The

co-production system of coal-based electricity generation and concrete production is used here to

illustrate the basic principles of the model framework. These systems are currently connected by the

use of fly-ash, a waste by-product from coal fuelled electricity generation, as an additive in concrete

production that replaces some of the cement. This reuse of fly-ash has multiple benefits, including

carbon emission reductions and an improvement in the structural properties of the concrete.

Interventions in coal electricity generation to introduce biomass or solid recovered fuels as a

replacement for coal it increased the biogenic and alternative energy production but it renders the slag

unusable as a cement replacement due to the higher alkaline content of the new fly-ash waste –

increasing so the negative environmental value of slag by making it an unrecoverable waste instead of

a secondary raw material. The change in complex dimensions of value in this system resulting from an

intervention upstream the waste generation illustrates the need for an integrated, whole systems

approach.

Keywords: Solid waste management; Resource recovery; Circular economy; Complex value

optimisation; Modelling; Framework

WASCON 2015 – Santander, 10–12 June 2015 2

1 Introduction

Circular economy and resource efficiency feature in the top priorities of the European Commission

(EC), aiming to establish a common and coherent EU framework for sustainable management of

resources throughout their life-cycle. The EC is presenting an ambitious revised circular economy

package in late 2015 to accelerate the transition to a more circular system of resource flows along the

full supply chain. Taking optimal decisions on retaining as much as possible the original value of

materials and functionality of products/items/compounds before they become waste, and on recovering

value from wastes, require new ways of quantifying traditional industrial production, consumption and

resource recovery systems and the underlying materials flows, taking into account all dimensions of

value (socio-economic, environmental, technical, and functional) and their mutual trade-offs.

Transforming the world into a more resource-efficient place necessitates tools capable of an evidence-

based transition to circular economy. There is need to combine economic, technical and social

valuation approaches with protection of the environment. The Complex Value Optimization Resources

Recovery (C-VORR) research project aims to develop such next generation tools, going beyond

conventional methods of estimating value and providing a robust, coherent and impartial approach for

making the transition to a resource-efficient future. This new system approach attempts to combine

and substantially extend the methodologies of life cycle assessment (LCA) and material flows analysis

(MFA), providing so new insights on the performance of systems on circular economy goals.

Existing approaches generally consider a single aspect (profit, carbon) at a time e.g. the “R1” energy

efficiency input-output formula for energy from waste (EfW) operations. Alternatively, they collapse

multiple dimensions of value onto just one (usually financial), as in ecosystem services. Life cycle

assessment (LCA) is a widely used methodology for assessing the environmental impacts of products

and services, including all stages of the life cycle. In LCA, all environmental issues connected with the

function of a process, product or activity, within a system, are identified and analysed in terms of

various potential environmental impacts. This product need not be a material and hence an LCA model

does not necessarily provide a mass balanced description of the system. This is in contrast with

material (MFA) and substance flow (SFA) models where activities are linked by the flows of materials

or substances only. MFA models are defined by a balance equation where the change in stock of every

material in every activity must be equal to the inflow minus the outflow. The proposed novel

framework and tool consists of a mass balanced material stock and flow model for the system (MFA)

that includes all materials identified as carrying significant value as resources as well as other

activities without mass flow links that also contribute significantly to social or environmental impacts

(LCA). Trade-offs of the different dimensions of value is considered and optimisation for such

multiple values is attempted.

2 Methodology

The new methodology under development (Figure 1) aims to study the systems in sufficient detail to

enable a transparent illustration of the value of resource flows and how changing system

configurations impact on this.

The new methodological framework (Figure 1) to assess the complex value implications of alternative

scenarios for product/waste systems includes a narrative led identification and the development the

dimensions of value that are relevant to a particular system and its stakeholder (framework + value

flow analysis models). This is formalised as a set of scenarios for alternative system configurations

and metrics that will be used for the value assessment of these scenarios. The assessment is enabled by

a model of the stocks and flows of the physical (material, product and energy) constituents as well as

the value properties of the system, explicitly considering selection of set of values and metrics for

evaluation, internal loops, system boundaries and uncertainty, while extending significantly in the

socioeconomic evaluation of the resource recovery.

WASCON 2015 – Santander, 10–12 June 2015 3

Figure 1. Integrated whole system approach to recover value from complex waste processing systems

The framework is co-developed with a set of four case studies which inform the methodologies for

value selection, scenario and metric development, and modelling approach. The methodology can be

applied to any industrial system to find optimal pathways for different sets of values in any point of

the supply chain (downstream/upstream) to capture and retain values currently wasted or dissipated

into waste. In this work, the co-production system of coal based electricity generation and concrete

production is used to illustrate the model framework.

3 Results and discussion

Fossil fuel based electricity generation and concrete production are both major contributors to the total

carbon emissions of the UK. Coal fired power stations are the most carbon intensive and polluting

parts of the UK’s energy system. The only potential to reduce carbon emissions from this process is to

use carbon capture and storage (CCS), or to use biomass / partly biogenic solid recovered fuels (SRF)

to replace some of the coal. Concrete production is carbon intensive primarily because of the very high

temperatures required for making cement. Carbon emissions in concrete production can be reduced by

replacing some of the cement in concrete with alternatives such as, coal fly-ash, a waste product of

coal electricity generation. The benefit of replacing some cement with fly-ash is not only evident in

reducing the associated carbon emissions, but also by improving the structural properties of the

concrete. The two production systems are hence linked as the by-product of the one is used as the raw

material of the other.

The policy pressure to reduce carbon emissions is leading coal fired power stations to convert to

biomass and /or SRF co-firing. Coal fly ash has been used as a technical addition for concrete for

years and a decision to partially replace coal with either biomass or SRF with the aim of reducing

carbon emissions and costs could come with significant side-effects. One of these is the increase in the

alkaline and unburnt carbon contents of the fly-ash waste, rendering it less usable / unusable as a

cement substitute in concrete. This would lead to the disposal of the fly-ash by-product, breaking the

chain that links the electricity with the cement production system and diminishing the value recovered

from the fly ash.

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The analysis of the environmental, technical, economic and social value of the co-production system of

coal based electricity generation and concrete production, and the implications imposed on this based

on the new scenario (Figure 2), is going to provide insights to the potential recovery of value.

Figure 2. Co-production system of coal based electricity generation and concrete production: co-combustion of

biomass or solid recovered fuels (SRF) changes the properties of fly ash, rendering it less suitable for concrete

production.

4 Conclusions

The innovative, powerful framework and tool that is going to be developed for enabling the evaluation

of various resource recovery systems based on the multiple dimensions of value will allow researchers

and industry practitioners to:

Obtain better knowledge and take optimal decisions over systems and their material flows.

Identify where resource-related values are lost or dissipated within the system.

Exemplify potential loops based on circular economy goals and mechanisms to capture

different dimensions of values along the full supply chain (upstream and downstream).

Assess the effects of interventions on the performance of the system.

Establish new economic models that prevent value dissipation and promote value creation

according to the goals of circular economy.

Acknowledgements

This research is funded by the Natural Environment Research Council (NERC) and the Economic and

Social Research Council (ESRC) (grant number: NE/L014149/1), with additional support from the

Department for Environment, Food & Rural Affairs of UK (DEFRA), and in kind contribution from

an extensive network of Project Partners and Supporters, to whom we express our gratitude. Opinions

expressed here are the authors’ alone.

Electricity

Production

Concrete

Production

Bottom ash Concrete waste

Water

Aggregate

Cement

ELECTRICITY CONCRETE

F

lya

sh Biomass

or SRF

Coal

Electricity

Production

Concrete

Production Coal

Fly ash

Bottom ash Concrete waste

Water

Aggregate

Cement

ELECTRICITY CONCRETE