Industrial Symbiosis (IS) is the process by which waste flows or by‐products of an industry or industrial process become the raw materials or inputs for another. Local or wider co-operation is essential to set up industrial symbiosis schemes. Application of this concept allows materials and resources to be used in a more sustainable way and contributes to the creation of a circular economy. In practical terms, it can help to reduce the need for virgin material and waste disposal and also to reduce energy use and emissions, whereby it can create new revenues stream for the companies and organisations involved.

This toolkit aims to present a range of pathways and available methodologies that support the move from anecdotal one-off resource synergies to a systematic application of resource synergies as a means to increase resource productivity and competitiveness.

Industrial symbiosis framework

An IS is a local collaboration scheme where different companies and organisations purchase and sell each residual type of products form other companies and organisations. This exchange results in mutual economic and environmental benefits, meaning that two or more companies and organisations become interdependent on each other for their resource or energy streams. For instance, heat generated that is not further used by one company, can be used as a source of heat by another company, displacing the need for new heat generation. Similarly, a company may buy pre-owned equipment e.g. boiler, grinders, furniture, from another company, with the prerequisite that the equipment meets all requirements and technical specifications of the interested company. Figure 1 shows the functionalities of the industrial ecology, which is the overarching frame for industrial symbiosis.

The application of the IS concept is rather vast and although no specific boundaries can be defined, general guidelines can be developed. The residuals and by products vary vastly across sectors and companies, even within the same sector, and thus the development of specific guidelines for each sector may limit the IS choices. However, specific applied examples from a number of sectors are listed below, which aim to provide inspiration to the companies (Table 1).

Sector	Description of the application of the IS concept
Fabricated metal products manufacturing (Antonopoulos et al., 2020) (collaborating companies do not need to belong to the same sector)	Reuse of waste streams, including material waste from metal product fabrication, e.g. cake, scrap, coating powder and solvents, as well as energy, e.g. steam, hot water or air Closing the loop of valuable materials e.g. special metal alloys. Linking materials demand or equipment need with waste streams or standby periods, back-up or redundant equipment in other companies. Identifying logistical opportunities, e.g. empty return routes for a neighbouring company which can be put to profitable use.
Food and beverage manufacturing (Dri et al., 2018) (collaborating companies do not need to belong to the same sector)	Exploiting collaborations with neighbouring companies for the use of residuals or by products for the generation of electricity, heat, cooling and steam e.g. stone/kernel from fruits. Investigating the exploitation of CO2 recovery generated during beer production form the tops of the fermentation tanks/vessels, the maturation vessels and the bright beer tanks.
Electrical and Electronic equipment manufacturing (Antonopoulos et al., 2016) (collaborating companies do not need to belong to the same sector)	Providing other companies with by-products that they can use as input materials, or, respectively by using by-products from other companies. The partner company does not need necessarily belong to the same sector. Suitable materials include re-used/refurbished components from other electrical and electronic equipment, but also materials like metal sections, wood etc. from other sources that can be used, for instance, for the casing of electric and electronic appliances.

In practical terms, to get started with IS, companies can follow the following steps:

• Identify opportunities by mapping energy or resource streams and their value/costs
• Map all stakeholders in the process
• Search (locally) for partner companies
• Identify the knowledge gaps and support needs to further elaborate the opportunity
• Define and setup (small scale) experiments
• Gradually extend the number of involved partners to build up a more robust network

However, for many companies the application of the IS concept might be hampered where the necessary networks or circumstances for this approach do not exist. This is relevant in cases of high transport costs, dispersed production structures and sub-optimal economies of scale. For instance, when residuals or by-products have to be transported over long distances, the economic feasibility of the IS concept is at risk and might be limited. Another limiting factor is the lack of knowledge and insight in potential valorisation routes for residuals and by-products. Moreover, the difficulty in finding sufficient and relevant information on how and where suitable potential partners/clients can be found constitutes a limiting factor for the application of the IS concept. Thinking outside the box pays off: valorisation routes can often be found in other sectors, but looking beyond the borders of a specific sector often implies entering unfamiliar areas (European Commission, 2016).

Cluster actors can play a key role in this context by facilitating access to information, disseminating the tools and ideas of industrial symbiosis and brokering partnerships. It is therefore of paramount importance to raise awareness of IS among all members of the ECCP community.

Synergies, distinction into direct and indirect

The achievement of an effective and successful IS scheme is based on setting up a type of synergy based on materials and/or energy exchange that can be applied in the industries and can be scaled up for many different sites in Europe. The literature makes a distinction in the synergies between direct and indirect. Direct synergies refer to those in which the stream is directly used, or with light technology/processing, whereas the indirect are cases for which the stream requires a prior modification or a treatment before reuse, usually offered by a third party.

Available toolkits and methodologies to apply IS

The IS concept can become operational through various pathways. Industry practitioners can be self-organised or can setup suitable cooperation schemes based on the needs of their companies and the available resources of other adjacent companies. However, the analysis of the literature showed that stakeholders have knowledge gaps in respect to the application of IS (Lybaek et al., 2021). Therefore, pathways that can facilitate the learning process on how to detect and apply various industrial symbiosis techniques, can help fill out the stakeholders’ knowledge gap and at the same time act as a driver to enable the implementation of the IS concept.

Lawal et al., (2021) reviewed recently the IS tools and methodologies available in the literature and concluded that these tools cannot be easily used by industry practitioners on real case studies. At the same time, a number of EU funded research projects deal with the development of guidelines and methods that can enable industry practitioners to apply the IS concept.

The Cambridge Value Mapping Tool (Bocken et al., 2013; Vladimirova, 2016) aims to identify the ‘value uncaptured’ in the form of failed value exchanges, such as missed value, destroyed, surplus, absence and opportunity. Therefore, the practitioners can obtain a deeper understanding of value and create new economic and environmental benefits for their business.

The EPOS toolbox is another web-based platform that includes a wide range of key performance indicators, such as climate change, operating costs etc. The user looks in the tool’s database for available synergies based on the type of the company, customizes the parameters and assesses the synergies that are detected by the tool. The BE CIRCLE tool aims to enable the design of both cities and industrial clusters with closed resource loops i.e. of energy, water, materials. This tool is suitable for projects (detecting ways of collaboration) at local scale since the main principles are: i. resource mapping of industrial and urban territories, ii. contribution to territorial development, iii. optimisation of the territorial integration of a specific technology and iv. collaborative processes and co-built scenarios. Additional information for each tool can be found below.

Cir©Lean is the European Network of businesses and SMEs for industrial symbiosis that aims to support the setup and pilot operation phase of a network of businesses and SMEs to seize industrial symbiosis business opportunities.

Moreover, the SCALER project has recently gathered pathways that can increase IS (Vladimirova et al., 2019). Vladimirova et al., (2019) reviewed extensively the available tools and methodologies that can be used at full scale and can increase IS.

Additional information for the IS tools

Cambridge Value Mapping Tool

EPOS

BE CIRCLE

Cir©Lean

NB 1. This list of tools is not exhaustive; the readers can take inspiration from this list and look up for similar tools. Moreover, the reader may refer to the SCALER project where more IS tools are described in detail.

2. Stakeholders can make use entirely or partly of the presented tools and methodologies and apply the IS as appropriate in their cases.

Literature references

Antonopoulos I., Canfora P., Gaudillat P., Dri M., Eder P., Best Environmental Management Practice in the Fabricated Metal Products manufacturing sector, EUR 30025 EN, Publications Office of the European Union, Luxembourg, 2020, ISBN 978-92-76-14299-7, doi:10.2760/894966, JRC119281

Antonopoulos I., Canfora P., Gaudillat P., Dri M. (2016), Best Environmental Management Practice in the Electrical and Electronic Equipment manufacturing, available online at: https://susproc.jrc.ec.europa.eu/product-bureau/sites/default/files/inline-files/BEMP_EEE_Manufacturing.pdf.

Bocken, N. M. P., Short, S. W., Rana, P. and Evans, S. (2013), A value mapping tool for sustainable business modelling, Corporate Governance, 13 (5), pp. 482-497.

Dri M., Antonopoulos I. S., Canfora P., Gaudillat P., Best Environmental Management Practice for the Food and Beverage Manufacturing Sector, JRC Science for Policy Report, EUR 29382 EN, Publications Office of the European Union, Luxembourg, 2018, ISBN 978-92-79-94313-3, doi:10.2760/2115, JRC113418.

European Commission; Study on the Energy Saving Potential of Increasing Resource Efficiency. Final Report, Brussels, 2016, available online at: http://ec.europa.eu/environment/enveco/resource_efficiency/pdf/final_report.pdf.

GPEM, 2015, Research Projects in Industrial Ecology and Circular/Green Economy. School of Geography Planning and Environmental Management, available online at: http://www.gpem.uq.edu.au/industrial-ecology-opportunities.

Lawa M., Wan Alwi S.F., Manan Z.A., Shin Ho W. (2021), Industrial symbiosis tools—A review, Journal of Cleaner Production, 280(1), 124327.

Lybaek R.T., Christensen T.B., Thomsen T.P. (2021), Enhancing policies for deployment of Industrial symbiosis – What are the obstacles, drivers and future way forward? Journal of Cleaner production, 280(2), 124351.

Vladimirova, D. (2016), The Cambridge Value Mapping Tool, IfM Review, Issue 5, p. 24., https://www.ifm.eng.cam.ac.uk/news/the-cambridge-value-mapping-tool.

Vladimirova, D., Miller, K., Evans S. (2019), Pathways to increase industrial symbiosis, SCALER project, Scaling European Resources with Industrial Symbiosis, available online at: http://bit.ly/D2-4_SCALER.