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1. Proof of X: Experimental Insights on Blockchain Consensus Algorithms in Energy Markets

   Machacek, Travis; Biswal, Milan; Misra, Satyajayant (January 2021, Innovative smart grid technologies)

   The current centralized model of the electricity market is not efficient in performing distributed energy transactions required for the transactive smart grid. One of the prominent solutions to this issue is to integrate blockchain technologies, which promise transparent, tamper-proof, and secure transaction systems specifically suitable for the decentralized and distributed energy markets. Blockchain has already been shown to successfully operate in a microgrid peer-to-peer (P2P) energy market. The prime determinant of different blockchain implementations is the consensus algorithm they use to reach consensus on which blocks/transactions to accept as valid in a distributed environment. Although different blockchain implementations have been proposed independently for P2P energy market in the microgrid, quantitative experimental analyses and comparison of the consensus algorithms that the different blockchains may use for energy markets, has not been studied. Identifying the right consensus algorithm to use is essential for scalability and operation of the energy market. To this end, we evaluate three popular consensus algorithms: (i) proof of work (PoW), (ii) proof of authority (PoA), and (iii) Istanbul Byzantine fault tolerance (IBFT), running them on a network of nodes set up using a network of docker nodes to form a microgrid energy market. Using a series of double auctions, we assess each algorithm’s viability using different metrics, such as time to reach consensus and scalability. The results indicate that PoA is the most efficient and scalable consensus algorithm to hold double auctions in the smart grid. We also identified the minimum hardware specification necessary for devices such as smart meters, which may run these consensus algorithms. 

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2. Blockumulus: A Scalable Framework for Smart Contracts on the Cloud

   https://doi.org/10.1109/ICDCS51616.2021.00064  

   Ivanov, Nikolay; Yan, Qiben; Wang, Qingyang (July 2021, 2021 IEEE 41st International Conference on Distributed Computing Systems (ICDCS))

   Public blockchains have spurred the growing popularity of decentralized transactions and smart contracts, especially on the financial market. However, public blockchains exhibit their limitations on the transaction throughput, storage availability, and compute capacity. To avoid transaction gridlock, public blockchains impose large fees and per-block resource limits, making it difficult to accommodate the ever-growing high transaction demand. Previous research endeavors to improve the scalability and performance of blockchain through various technologies, such as side-chaining, sharding, secured off-chain computation, communication network optimizations, and efficient consensus protocols. However, these approaches have not attained a widespread adoption due to their inability in delivering a cloud-like performance, in terms of the scalability in transaction throughput, storage, and compute capacity. In this work, we determine that the major obstacle to public blockchain scalability is their underlying unstructured P2P networks. We further show that a centralized network can support the deployment of decentralized smart contracts. We propose a novel approach for achieving scalable decentralization: instead of trying to make blockchain scalable, we deliver decentralization to already scalable cloud by using an Ethereum smart contract. We introduce Blockumulus, a framework that can deploy decentralized cloud smart contract environments using a novel technique called overlay consensus. Through experiments, we demonstrate that Blockumulus is scalable in all three dimensions: computation, data storage, and transaction throughput. Besides eliminating the current code execution and storage restrictions, Blockumulus delivers a transaction latency between 2 and 5 seconds under normal load. Moreover, the stress test of our prototype reveals the ability to execute 20,000 simultaneous transactions under 26 seconds, which is on par with the average throughput of worldwide credit card transactions. 

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3. Peer-to-Peer Energy Trading in DC Packetized Power Microgrids

   https://doi.org/10.1109/JSAC.2019.2951991  

   Zhang, Haobo; Zhang, Hongliang; Song, Lingyang; Li, Yonghui; Han, Zhu; Poor, H. Vincent (September 2019, IEEE Journal on Selected Areas in Communications)

   As distributed energy resources (DERs) are widely deployed, DC packetized power microgrids have been considered as a promising solution to incorporate DERs effectively and steadily. In this paper, we consider a DC packetized power microgrid, where the energy is dispatched in the form of power packets with the assist of a power router. However, the benefits of the microgrid can only be realized when energy subscribers (ESs) equipped with DERs actively participate in the energy market. Therefore, peer-to-peer (P2P) energy trading is necessary in the DC packetized power microgrid to encourage the usage of DERs. Different from P2P energy trading in AC microgrids, the dispatching capability of the router needs to be considered in DC microgrids, which will complicate the trading problem. To tackle this challenge, we formulate the P2P trading problem as an auction game, in which the demander ESs submit bids to compete for power packets, and a controller decides the energy allocation and power packet scheduling. Analysis of the proposed scheme is provided, and its effectiveness is validated through simulation. 

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4. Robust P2P Connectivity Estimation for Permissionless Bitcoin Network

   https://doi.org/10.1109/IWQOS52092.2021.9521287  

   Hong, Hsiang-Jen; Fan, Wenjun; Wuthier, Simeon; Kim, Jinoh; Zhou, Xiaobo; Chow, C. Edward; Chang, Sang-Yoon (June 2021, IEEE/ACM 29th International Symposium on Quality of Service (IWQOS))

   Blockchain relies on the underlying peer-to-peer (p2p) networking to broadcast and get up-to-date on the blocks and transactions. It is therefore imperative to have high p2p connectivity for the quality of the blockchain system operations. High p2p networking connectivity ensures that a peer node is connected to multiple other peers providing a diverse set of observers of the current state of the blockchain and transactions. However, in a permissionless blockchain network, using the peer identifiers—including the current approach of counting the number of distinct IP addresses and port numbers—can be ineffective in measuring the number of peer connections and estimating the networking connectivity. Such current approach is further challenged by the networking threats manipulating the identifiers. We build a robust estimation engine for the p2p networking connectivity by sensing and processing the p2p networking traffic. We implement a working Bitcoin prototype connected to the Bitcoin Mainnet to validate and improve our engine’s performances and evaluate the estimation accuracy and cost efficiency of our estimation engine. 

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5. Peer-to-Peer Energy Trading and Grid Impact Studies in Smart Communities

   https://doi.org/10.1109/ICNC47757.2020.9049665  

   Elliott, Eric; Shanklin, Nicholas; Zehtabian, Sharare; Zhou, Qun; Turgut, Damla (February 2020, 2020 International Conference on Computing, Networking and Communications (ICNC))

   The rise of peer-to-peer (P2P) marketplace paradigms has transformed existing marketplace models, but the extent to which this approach can be applied to the energy marketplace has yet to be considered. In this paper, we examine existing approaches taken in the application of a P2P paradigm to the energy marketplace, further presenting an approach towards facilitating an online P2P energy marketplace, implementing a prototype P2P web application named SolTrade. Furthermore, we submit initial statistics based on simulated transactions facilitated through the platform, which illustrate the physical impact of marketplace transactions on the energy grid. In particular, these results show that, as the number of users rises, the chance of overloading the grid rises, but the chance of the grid being unable to sustain itself without an external source of energy falls. 

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