This paper provides a literature review consolidating aspects of theory and implementation regarding the concept of the Circular Economy (CE) and provides guidance for further reading on the different aspects of CE. The authors argue that the dissemination of the CE is hampered due to divergent approaches populating the field. Furthermore, a lack of analysis of the available CE implementation strategies and the CE implementation experience, is limiting the effectiveness of CE implementation. The consequence of which, is putting the proposed CE investments at risk. The paper seeks to address these two issues by clarifying the definition of CE and by providing tools for CE implementation.

From the literature review, the paper develops two comprehensive CE tools. The first, is a CE Strategies database that includes 45 strategies for different parts of the value chain. The second, is a CE Implementation database that describes over 100 case studies for the 45 strategies.

CE promotes economic growth by creating new businesses and job opportunities, saving materials cost, dampening price volatility, improving security of supply while at the same time reducing environmental pressures and impacts.

The literature review analyses the different understandings of the CE and finds four common threads: stock optimisation, eco-efficiency and eco-effectiveness, waste prevention through the strategy of 4Rs (Reduce, Reuse, Recycle and Recover) and finally, the concept of circularity.

The literature review draws on 118 documents that have ‘circular economy’ as their primary topic. The reviewed literature is used to develop the CE Database. This section discusses case studies on China and European countries like Sweden and the Netherlands. China is applied as a case study as an example of an early adopter of CE through its 2002 national development strategy.

The constructed CE Strategies Database summarises the methods of CE implementation described in the literature. CE is a result of convolution of several sustainability concepts so, the strategies used are often borrowed from other sustainability fields. The Database is envisaged as a basis for designing CE implementation by actors on a system scale (NGOs, sector associations and policy makers) and by the actors managing a value chain or a part of a value chain.

The CE Implementation Database contains a mixture of cases from various actors, including academia, NGOs, consultancy and companies. These actors may have different agendas and standards. Therefore, when using the CE Strategies Database and the CE Implementation database as a search engine for finding appropriate strategies, it is recommended to pay attention to the agenda and standards of the entity which has developed each of the found cases.

1. The economic case for sustainable finance is made by offering CE as a solution to the unsustainable character of the majority of current value chain models through suggesting implementation strategies across product life-cycles such as, green procurement, bio-based materials, energy efficiency and recovery, among others.
2. The CE Strategies Database features 45 strategies that are suitable for application in different parts of the value chain.
3. Japan is leading in international development when it comes to sustainable resource management by considering hidden flows and the global impact of Japan's consumption in nationwide policies.
4. In developing countries like In China, the informal collection and recycling sector is substantial and is managed by a top-down CE policy, where the policy seeks to streamline the waste and secondary materials flow through the official channels only, including bans or restrictions on informal recycling.
5. On the other hand, in developed countries there are examples of the government initiatives to decentralise recycling, for example in Sweden, where they promote reuse and repair centres as well as offer tax breaks for the repair shops.
6. In the European context, a 2015 report by the Ellen MacArthur Foundation, Growth within: a circular economy vision for a competitive Europe, puts forward the ReSOLVE framework based on six business actions for businesses and countries wanting to move towards the circular economy: Regenerate, Share, Optimise, Loop, Virtualise, and Exchange.
7. In the UK, it is has been estimated that a circular economy could help generate 50,000 new jobs and €12 billion of investment.
8. In the Netherlands the potential benefits of a circular economy have been estimated to amount to €7.3 billion a year in market values, leading to 54,000 jobs and numerous environmental benefits.
9. There is no commonly agreed term or definition for CE which has limited the pool of reviewed literature to the keyword 'circular economy' in either the title, keywords or an abstract of the document, which means that relevant literature using a different term to CE have been excluded.
10. See Appendix A. Supplementary data for a comprehensive spreadsheet on the circular economy implementation database including over 100 implementation cases for 35 of the total 45 strategies described in the CE Strategies Database.