ABSTRACT
Blockchain has made an impact on today's technology by revolutionizing the financial industry through utilization of cryptocurrencies using decentralized control. This has been followed by extending Blockchain to span several other industries and applications for its capabilities in verification. With the current trend of pursuing the decentralized Internet, many methods have been proposed to achieve decentralization considering different aspects of the current Internet model ranging from infrastructure and protocols to services and applications. This paper investigates Blockchain's capacities to provide a robust and secure decentralized model for Internet. The paper conducts a critical review on recent Blockchain-based methods capable for the decentralization of the future Internet. We identify and investigate two research aspects of Blockchain that provides high impact in realizing the decentralized Internet with respect to current Internet and Blockchain challenges while keeping various design in considerations. The first aspect is the consensus algorithms that are vital components for decentralization of the Blockchain. We identify three key consensus algorithms including PoP, Paxos, and PoAH that are more adequate for reaching consensus for such tremendous scale Blockchain-enabled architecture for Internet. The second aspect that we investigated is the compliance of Blockchain with various emerging Internet technologies and the impact of Blockchain on those technologies. Such emerging Internet technologies in combinations with Blockchain would help to overcome Blockchain's established flaws in a way to be more optimized, efficient and applicable for Internet decentralization.
ABSTRACT
Life cycle assessment (LCA) modelling of resource-related technologies can be challenging in the context of circular economy, bioeconomy, recycling and integrated waste management, where materials are recirculated within processes and undergo chemical-physical transformations. This implies redefinition of physical flows within the LCA model. Additionally, physical flows may have non-linear responses to changes in model parameters and background processes, involve activities such as extraction of materials and chemical substances, and directly affect emissions. However, these non-linear responses and links between physical flows within technologies are often neglected. In this study, four novel LCA modelling features are provided: i) mixing and/or redefinition of physical flows; ii) substance recirculation within physical flows; iii) integration of physical flows from background processes into foreground processes; and iv) (multi)-conditional sequence flows, while maintaining substance and material balances throughout the system. As an expansion of EASETECH, an existing user-friendly LCA software tool for modelling of environmental technologies, a "process editor" (EASETECH+) allows implementation of these four features into EASETECH. The modelling features are implemented into EASETECH as seven individual processes "modules" and applied in an illustrative case-study focusing on anaerobic digestion of source-segregated organic household waste. The case-study demonstrated that the new modelling approach for physical flows, including recirculation, links between flows from background to foreground processes and conditional flows, considerably affected both results and interpretation of the LCA modelling. The recommendation is that process-oriented LCA modelling as presented here can provide critical new insight into the environmental performance of waste technologies and systems.
