The evolution of Distributed Ledger Technologies since the first blockchain constitutes an opportunity for digital transformation in many social and economic contexts. This transformation will become even more intense in the post–covid-19 economic scenario. One of the most significant changes in the transformation consumers have undergone in their perception of the environment and of the sustainability of our societies. The circular economy is an agent of change that helps minimize humankind’s impact on the planet. And this change must be aligned with the sustainable development goals of the 2030 Agenda. Since its inception, blockchain technology has represented an opportunity for transparency, immutability, and persistence in the processes in which it intervenes, allowing it to be incorporated into easily traceable, disintermediated networks. By implication, this suggests we can move towards a verifiable, reliable, circular economy. In this chapter we cover the fundamentals of blockchain technology including its history, the elements that define distributed ledger technologies, and how they have evolved into their most recent forms—e.g., Hashgraph, Direct Acyclic Graphs, Holochain or Neural Distributed Ledgers—which represent scalable, efficient, innovative solutions aligned with sustainability goals and facilitating the efficient, sustainable management of circular economy projects. Finally, drawing on striking use cases in Spain, we describe the use of blockchain technology in circular economy projects, and its operating status, as examples of ideas for the future development of models that may reach the market.
