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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Journal of King Saud University</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.1007/978-3-031-28694-0\_26</article-id>
      <title-group>
        <article-title>Besu vs. Quorum: Comparative Analysis in the Context of Simulated Energy Communities</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Giuseppe Antonio Pierro</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Luisanna Cocco</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Roberto Tonelli</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Mathematics and Computer Science, University of Cagliari</institution>
          ,
          <addr-line>Cagliari</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2020</year>
      </pub-date>
      <volume>3</volume>
      <fpage>666</fpage>
      <lpage>675</lpage>
      <abstract>
        <p>This paper presents a comparative analysis of two private blockchains, Besu and Quorum, both built on the Ethereum Virtual Machine (EVM) in order to manage the simulated production, consumption and exchange of energy in the context of a Renewable Energy Community (REC). The research focuses on simulating energy production through photovoltaic panels within a community, utilizing energy storage systems. The simulated data serve as input for two private blockchains, leveraging smart contracts to transform the simulated energy production into tokens. The study further explores the simulation of tokenized energy transactions, encompassing buying and selling within the energy community. The final phase involves a comprehensive comparison of Besu and Quorum, evaluating their computational resource usage and performance metrics. The findings contribute to the comprehension of blockchain technologies within energy communities, ofering valuable insights into the eficiency and suitability of BESU and QUORUM for tokenized energy transactions. Our research confirms that simulating an energy community scenario with 20 producers, trading energy via tokens, demonstrates no performance gap in terms of TPS and RPS between the two blockchains. However, at larger scales, Quorum appears to outperform Besu in terms of both TPS and RPS eficiency.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;BesuBlockchain</kwd>
        <kwd>Ethereum</kwd>
        <kwd>Proof-of-Stake</kwd>
        <kwd>Besu</kwd>
        <kwd>Quorum</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>Up until about ten years ago, electricity generation was centralized, with a few large power plants
fueled by fossil fuels like gas, coal, and oil spread across the country. These plants produced significant
amounts of energy that was distributed through a network to users, ensuring a reliable electricity
supply. This method had a high environmental cost due to the CO2 and other pollutants emitted during
fossil fuel electricity production.</p>
      <p>As a result it led in the last decade to a shift towards a decentralized model, to address climate change
by promoting renewable energy sources such as wind and solar power. This new decentralized model
presents challenges for the electricity grid, including managing electricity from various sources and
dealing with the intermittent nature of renewable energy generation. Within this model advanced
services for individual users and the coordination of various stakeholders with diferent roles and
objectives, such as market operators and maintenance workers, are made possible through information
systems and control and management systems that play a crucial role. A key element in this model is the
"smart metering" system that enables remote reading and management of electricity meters, allowing
for automatic and frequent monitoring from a distance. The energy system becomes more dynamic
and remotely controllable, allowing network managers to intelligently oversee available electricity by
monitoring real-time consumption patterns of users. This enables users to optimize their electricity
usage by operating electrical appliances during periods of lower energy prices. Additionally, retailers
can ofer customers electricity divided into hourly bands, reflecting the varying value of electricity at
diferent times of the day and year.</p>
      <p>Renewable energies are growing rapidly globally as found by the International Energy Agency (IEA)
in its Renewables 2023 report (https://www.iea.org/reports/renewables-2023). IEA predicts that by
2028 the share of renewable electricity in Europe will be 61%, thanks in part largely to unprecedented
installations of solar panels, up from the current 41%.</p>
      <p>In this context emerging technological trends are playing a pivotal role in shaping these systems.
For example Internet of things (IoT) allows for more intelligent and conscious use of energy, while
Blockchain technology allows new automated payment systems, or exchanges of goods and services
within the so called sharing economy.</p>
      <p>In particular, in a context where energy production can be intermittent and also unpredictable, such
as in the case of solar power, wind power, and hydropower, that rely on natural elements such as
sunlight, wind, and water flow, which can vary in availability and intensity over time, the blockchain
technologies combined with IoT devices can enable consumers to trade and purchase energy directly
from the grid rather than from retailers leveraging also the blockchain properties of immutability for
certifying production and exchange of energy in real time in a reliable framework. In addition, thanks
to this technology a customer can choose a renewable energy supplier, and verify their power source
thanks to the blockchain which allows to trace, moment by moment, the origin of the electricity that is
supplied, from the moment of generation to the final destination of consumption.</p>
      <p>This article was born in this context, and is part of two research projects within the framework of the
Italian government’s National Recovery and Resilience Plan (PNRR). Precisely, it is part of the Network
4 Energy Sustainable Transition (NEST) project, and the Ecosystem of Innovation for Next Generation
Sardinia (eINS) project.</p>
      <p>In the former project, a part of the research activities deals with the design and implementation of a
digital, distributed, peer-to-peer platform enabling a local token economy among consumers/prosumers
within a REC for the exchange of renewable energy among peers. In the latter project, a part of the
activities deals with the design and the implementation of a more complete platform that in addition to
the implementation of the local token economy just quoted, enables flexibility services and implements
a local token economy in which virtuous behaviors by REC users are converted in tokens used to buy
goods and services available within the REC, perfectly in accordance with the principles of a sustainable
economy.</p>
      <p>In both projects, within these research activities based on blockchain technology, the design and
implementation of an adequate blockchain infrastructure play a crucial role. Both projects leverage the
blockchain technology for the notarization of the energy consumption and production data in such a
way that becomes impossible to alter this data without leaving a trace. In addition they leverages this
technology for the conversion of the production of renewable energy and of the virtuous behaviors by
REC users into tokens.</p>
      <p>There are several diferent blockchain technologies available today, and all have diferent features and
functionalities. Blockchain technologies can be broadly divided into permissioned and permissionless
systems. While permissionless blockchains let anybody join and contribute without approval,
permissioned blockchains require users to seek authorization before they may access and use the network.
The consensus process that a blockchain uses to decide how transactions are approved and added to
the ledger is another important factor. As the purpose of research activities is to build a blockchain
infrastructure and, consequently, the deployment of a trustworthy and eficient blockchain solution,
a few crucial indicators must be assessed in order to ascertain how well these blockchain platforms
operate. These consist of transaction throughput, hence the speed at which legitimate transactions are
added to the blockchain, transaction latency, hence the length of time a transaction must remain in the
network after it is sent, and scalability. Thus the optimal Blockchain network infrastructure for the
specific use cases in these projects must be selected by carefully analyzing these indications, which
provide crucial insights into the capabilities and limitations of these diferent blockchain technologies.
This article focuses on this key part of the activities.</p>
      <p>Precisely aim of this article is the comparison between the performance of a Blockchain infrastructure
realized in Hyperledger Besu technology and a Blockchain infrastructure realized in Quorum technology.
The two networks implement two diferent mechanism of consensus. The former uses the Istanbul
Byzantine Fault Tolerance (IBFT) algorithm and the latter uses the Replicated State Machine Approach
(RAFT) algorithm. A concrete evaluation in a simulated scenario of the diferent blockchain technologies
can help in determining which technology is best suited in real world use cases of energy production
and exchange in a Renewable Energy Community where blockchain performances are a key factor to
ensure reliability of the entire framework.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Background</title>
      <p>In the realm of blockchain technology, the performance evaluation of the diferent blockchain
technologies holds significant importance for organizations seeking to implement robust and eficient
blockchain solutions. The evaluation of the performance of these platforms involves assessing various
key metrics such as transaction throughput that is the rate at which valid transactions are committed
to the blockchain, transaction latency that is the amount of time a transaction requires to be part of the
network from the moment it was submitted, and scalability. By conducting a thorough analysis of these
metrics, organizations can gain valuable insights into the capabilities and limitations of these technology,
enabling them to make informed decisions regarding the selection of the most suitable platform for
their specific use case. Among the several blockchain technologies, Hyperledger Besu and Quorum are
both widely recognized for their capabilities in facilitating secure and scalable blockchain networks
and this article focuses on evaluating the performance of these two blockchain under two diferent
consensus algorithms, specifically Istanbul Byzantine Fault Tolerance 2.0 (IBFT 2.0) for Hyperledger
Besu and Replicated State Machine Approach (RAFT) for Quorum have been selected for our use case.
In the following a brief description of these two blockchains and of the consensus algorithms selected
is reported.</p>
      <sec id="sec-2-1">
        <title>2.1. Hyperledger Besu and IBFT 2.0</title>
        <p>
          Hyperledger Besu is an open source Ethereum client developed by ConsenSys. It is designed to be
interoperable with other blockchain technologies and to support the so-called smart contracts, i.e.
contracts that are automatically executed when terms and conditions written directly in the code are
met. Hyperledger Besu supports the Solidity programming language, which is the most widely used
language for developing smart contracts on Ethereum, and also supports Vyper a language designed
to improve the security and auditability of smart contracts compared to Solidity. It supports the
Ethereum Virtual Machine (EVM) and the Web3 API, and therefore it supports the interaction with
smart contracts deployed on other Ethereum-based networks. Among its main features there is the
support for private transactions, which allow the use of the platform without exposing sensitive data
and its ability to process thousands of transactions per second. Hyperledger Besu supports multiple
consensus algorithms, therefore diferent selection possibilities for the set of validators that create new
blocks and validate transactions, thus allowing the choice of the approach that best suits the needs of
each use case. Among the algorithms Proof of Authority (PoA), proof of work (PoW), proof of stake
(PoS), and IBFT can be quoted. Let us give a brief description of the consensus mechanism IBFT 2.0.
It is built upon the IBFT for addressing the safety and liveness limitations of IBFT [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ]. As every
blockchain node, each IBFT 2.0 node maintains a local copy of the blockchain, and the first block, is
called genesis block. Each block B in the chain is cryptographically linked to another block in the chain.
In IBFT 2.0 the block to be added to the local blockchain, that is equal in every network node, represents
the child of the latest block that was added to the blockchain. So, the IBFT 2.0 blockchain is a linked list
of blocks, in which each block has a height h, defined as the number of links between that block and the
genesis block that has height h equal to 0. The IBFT 2.0 protocol can be modeled as running sequential
instances, that have to decide which Ethereum block, has to be added at height h of the chain. Only
a subset of nodes can participate in the h-th instance, hence only a subset of nodes can contribute to
take this decision. These nodes are called the validators of a specific block, hence related to a specific
height/instance h. All the other nodes that do not participate in the h-th instance are standard nodes.
The set of validators is deterministically computed as function of the chain of blocks from the genesis
block until the block with height h-1. For each instance there is a round, in which one of the validators
has to propose an Ethereum block for the height associated with the specific instance that he is running.
Once agreement is reached, a finalized block is created. It includes the Ethereum block and additional
information that allows all nodes in the network to verify that the finalised block was correctly added.
To add or remove a validator from the set relative to a specific block, validators for that block can vote.
The validator is added or removed from the set when more than half of the validators cast a consistent
vote.
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Quorum and RAFT</title>
        <p>Quorum is an open source project launched in 2016. It is a variant of the Ethereum blockchain designed
for an enterprise audience. GoQuorum is an open-source variant of Quorum, which is a permissioned
blockchain platform developed by JPMorgan Chase. Both platforms are based on the Ethereum protocol
and are designed for enterprise use cases. Both are lightweight forks of geth and are updated as geth
releases occur. Like Besu, Quorum supports private transactions and thanks to organization registries,
allowlists, and permissioning contracts it allows you to manage diferent authorization levels that
can be customized for diferent roles. It supports the solidity language for writing smart contracts
and is mainnet compatible. In Quorum the consensus protocols that can be used are based on voting
algorithms which do not require computational power, for example IBFT, or RAFT.</p>
        <p>
          Let us give a brief description of the consensus mechanism RAFT [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ], that is the mechanism adopted
in this article for the Quorum blockchain. The RAFT consensus algorithm distributes a state machine
across a cluster of computing systems to ensure that all nodes in the cluster agree on the same set of
state transitions, even in the event of failures. RAFT operates by electing a leader within the cluster,
with servers functioning as leaders, followers, or candidates if the leader is unavailable. The leader
oversees registry replication on other servers and handles client requests until a new leader is elected
in case of leader failure or disconnection. RAFT operates through a series of phases, including leader
election, log replication, and safety properties to maintain consistency and fault tolerance. With Leader
Election RAFT ensures a new leader is elected when the current leader fails, with Log Replication,
RAFT maintains synchronization between the leader’s server and other servers’ logs, and with the
safety property prevents other servers from requesting a registry entry at a specific index if a server has
already committed an entry for that index to maintain log consistency and execute the same commands.
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Related Work</title>
      <p>The concept of a smart grid has emerged as a modernized version of the traditional power grid, aiming
to efectively incorporate green and renewable energy technologies. The primary objective of the grid is
to establish a sustainable society. The smart grid is currently transitioning from a centralized structure
to a decentralized topology, and blockchain technology ofers promising features for its application in
the smart grid concept. Numerous literature articles explore this topic in depth.</p>
      <p>
        Mollah et al. [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] provided a comprehensive survey on the application of blockchain in smart grid,
identifying the security challenges of smart grid scenarios that can be addressed by blockchain. Musleh et
al. [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] examined benefits, methodologies, and technical obstacles associated with integrating blockchain
technology into the smart grid, introducing frameworks for blockchain-based applications in the
smart grid and demonstrating how blockchain can serve as the cyber-physical layer of the smart grid.
Mehdinejad et al. [5] presented a design and model for a completely decentralized peer-to-peer (P2P)
energy token market tailored for small-scale prosumers within a smart grid setting leveraging blockchain
technology. Agung et al. [6] leveraged blockchain technology as a means to oversee transactions within
the smart grid. Transactions are executed using smart contracts, with the network serving as a verifier
for these transactions ensuring the permanence of transactions, and guaranteeing the execution of
every transaction between generators and consumers. Doan et al. [7] presented a peer-to-peer (P2P)
energy trading system involving prosumers utilizing a double auction-based game theory approach
and blockchain technology to showcase the viability of real-time P2P trading. In this system, the
buyers adjust their energy purchase based on fluctuating electricity prices to optimize their benefits,
the auctioneer oversees the game, while the seller does not actively participate but ultimately achieves
maximum social welfare.
      </p>
      <p>An interesting web article entitled Blockchain technology for the renewable energy sector: A
comprehensive study [8] quotes the Brooklyn MicroGrid project, began in April 2016 (see web site
https://brooklynmicrogrid.com/) as the first real application of blockchain in RE. This project is based on
Ethereum blockchain technology and stores energy transactions. By utilizing smart contracts based on
Ethereum, the system enables customers to purchase extra renewable energy from prosumers through
a tokenized transaction system. Surplus energy generated by prosumers using rooftop solar panels
is transformed into tokens by smart meters installed in their residences, which can then be utilized
for direct trading in the energy market. This article investigated Blockchain use cases in the energy
sector, showing that 33% use cases is associated with decentralized energy trading, and 19% use cases is
associated with cryptocurrencies, tokens, and investments. Further, it classified Blockchain activities
in the energy sector according to the platform used and consensus algorithms, reporting that 60% of
applications are Ethereum-based solutions, and 55% adopt PoW algorithms. Furthermore, it claimed
that the trend, that is developing, is oriented towards private permissioned platforms that are most
attractive to enterprises. Also in our work, private permissioned platforms are selected as the more
suitable technology to develop blockchain based applications for REC, and specifically our choice of
Blockchain infrastructures fell on Hyperledger Besu and Quorum.</p>
      <p>In recent years, there has been a growing body of literature focusing on the evaluation of blockchain
technology performance. Monrat et al. [9] conducted a study of the performance and scalability of four
private blockchains, precisely of Ethereum, Quorum, Corda, and Hyperledger Fabric, by varying the
number of transactions and nodes and evaluating metrics such as throughput and network latency. Hao
et al. [10] proposed a method to evaluate the performance of some consensus algorithms in Ethereum and
Hyperledger Fabric private blockchain. The authors demonstrated that the PBFT algorithm surpasses
the PoW algorithm in terms of both average throughput and average delay, with the performance gap
widening as the number of transactions grows. Mostarda et al. [11] presented a performance analysis of
a permissioned blockchain in a real scenario in which validator nodes are geographically distant from
each other, and proposed a new benchmarking tool for Ethereum-like blockchains. Baliga et al. [12]
studied the throughput and latency characteristics of Quorum with diferent workloads and RAFT AND
IBFT consensus algorithms. Their findings revealed that implementing the RAFT algorithm results in
minimal changes to the system’s throughput when extending the block time, although latencies exhibit
a proportional increase. In terms of throughput, RAFT and IBFT are similar, with RAFT demonstrating
slightly superior performance at transaction rates exceeding 1650 tx/sec, while IBFT outperforms RAFT
marginally at lower transaction rates. In addition they showed that private contracts exhibit lower
throughput under heavier system loads, attributed to the additional overhead associated with secure
communication, than public contracts, particularly when the input transaction rate exceeds 600 tx/sec.
The system’s maximum sustainable load was found to be 900 tx/sec, beyond which consensus could not
be reached. Abdella et al. [13] proposed a permissioned Blockchain platform for Peer-to-Peer energy
trading using the IBFT consensus algorithm. This architecture operates on an auction mechanism,
requiring both consumers and producers to compete against each other to secure the auction win, and
through several smart contracts implements three diferent types of energy markets, payment settlement
and authentication functions. The authors developed this platform both using Hyperledger Besu and
Hyperledger Fabric blockchin platforms, and compared the performance of the IBFT algorithm with
Clique, PoW, and Raft consensus algorithms By analyzing transaction latency, transaction throughput
and fail rate they showed that IBFT has better performance.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Research Questions and Hypotheses</title>
      <p>The ever-growing demand for high-performance blockchain solutions necessitates a clear understanding
of diferent platforms’ capabilities. This research focuses on evaluating two prominent
Ethereumbased blockchains, Quorum and Besu, in terms of their ability to handle transaction and request
processing [14, 15].</p>
      <p>This section outlines the key research questions that will guide our investigation and the hypotheses
we aim to test. By addressing these questions, we hope to gain valuable insights into the performance
characteristics of Quorum and Besu.</p>
      <p>The following research questions serve as the foundation for our investigation:
4.1. Research Questions:
1. Which blockchain platform, Quorum or Besu, demonstrates a superior capability in processing
transactions per second (TPS) and requests per second (RPS)? This primary question aims to
identify the platform that ofers faster transaction and request handling.
2. How do the scalability characteristics of Quorum and Besu compare under varying workloads
and network conditions? Evaluating scalability is crucial, as real-world use cases can involve
lfuctuating transaction volumes and network pressures.
4.2. Research Hypothesis:
1. Null Hypothesis (H0): There is no significant diference in the TPS and RPS processing capabilities
between Quorum and Besu blockchains.
2. Alternative Hypothesis (H1): There is a significant diference in the TPS and RPS processing
capabilities between Quorum and Besu blockchains. We expect one platform to outperform the
other, and this research aims to identify which and under what conditions.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Research Methodology</title>
      <sec id="sec-5-1">
        <title>5.1. Set-up of the experimental system</title>
        <p>The two blockchains were set up with identical hardware resources but diferent software configurations
due to their distinct consensus mechanisms. Concerning the hardware resources, we utilized two Apple
2020 Mac mini with Chip M1 (8GB RAM, 256GB SSD), and a MacBook M2 with 16GB RAM and 500GB
SSD. Regarding the software configuration, it is imperative to diferentiate between Besu and Quorum
blockchains.</p>
        <p>In the software configuration of the Besu blockchain, we chose to deploy a network consisting of five
nodes, with four nodes serving as validators and one node fulfilling the role of an RPC node. Specifically,
Mac Mini devices were configured in a manner to host two virtual machines each, with each virtual
machine serving as a validator. The machine equipped with the M2 chip was utilized as the RPC node.
On each node, we installed Node.js version 20 and Java version 18. Java is a high-level designed to be
platform-independent, meaning that Java programs can run on any device or operating system that has
a Java Virtual Machine (JVM) installed.</p>
        <p>In the software configuration of the Quorum blockchain, each node is standardized with identical
software characteristics. Specifically, on machines equipped with M1 chips, we deployed two virtual
machines, while on machines equipped with M2 chips, a single virtual machine has been instantiated.
Moreover, across all nodes, we implemented version 20 of both Node.js and GoQuorum. This ensures
uniformity and consistency in the software environment across the entire blockchain network.
GoQuorum is an open-source Ethereum client developed by ConsenSys. It is based on the Go Ethereum (Geth)
client and is specifically designed for use in private or consortium blockchain networks. GoQuorum
provides features such as privacy, permissioning, and high performance, making it suitable for enterprise
blockchain applications.</p>
        <p>In order to simulate the production transactions of electricity generated by photovoltaic panels, we
employed a Node.js script that leverages the Web3 library. This script was utilized for conducting
simulations on both the Quorum and Besu blockchain platforms. For each simulated energy production
event, we correspondingly incremented the token associated with the owner’s address. By employing
this script across both blockchain platforms, we ensured methodological consistency in our simulations
and facilitated a seamless comparison of results between the two environments.</p>
        <p>In order to conduct stress tests and ascertain the maximum transaction throughput that both
blockchains could handle, we employed diferent tools tailored to each blockchain environment. This
approach allowed us to simulate higher transaction volumes and evaluate the scalability of each blockchain
platform under varying loads. Table 1 provides a comprehensive overview of the testing tools employed
to conduct stress tests on the Besu and Quorum blockchains.</p>
        <p>To evaluate the maximum achievable Transactions Per Second (TPS) on our Besu blockchain, we
employed the open-source Hyperledger Caliper tool. This industry-standard performance benchmarking
framework, available at https://github.com/hyperledger/caliper, is specifically designed for assessing the
capabilities of various blockchain platforms. Hyperledger Caliper facilitates comprehensive performance
analysis by generating detailed reports after each benchmark run. These reports capture critical metrics
such as TPS, transaction latency, resource utilization (CPU and memory), and transaction success/failure
rates. This valuable data empowers us to make informed decisions regarding our Besu network’s
performance optimization, pinpointing potential bottlenecks and areas for improvement.</p>
        <p>We leveraged Apache JMeter, an open-source performance testing tool, to assess the maximum
achievable Transactions Per Second (TPS) on our Quorum blockchain network. JMeter’s
platformindependent design, facilitated by its pure Java implementation, enabled us to conduct these tests
seamlessly across various operating systems. While ofering a user-friendly graphical user interface
(GUI) for test plan creation, JMeter empowers advanced users with scripting capabilities using languages
like BeanShell and JavaScript. This flexibility allowed for tailored automation and customization of test
logic, ensuring a comprehensive evaluation of our Quorum network’s transaction processing capacity.</p>
        <p>To assess the maximum capability of Besu and Quorum blockchains in handling JSON RPC requests,
we utilized two distinct tools. This phase allowed us to establish the upper bounds of processing
capacity for both Besu and Quorum blockchains It is pertinent to acknowledge that RPC serves as a
well-established communication protocol, facilitating applications in making remote procedure calls on
a server. JSON (JavaScript Object Notation) has emerged as the preferred format for data exchange
between applications engaged in RPC calls. Consequently, an RPC JSON request embodies a message
formatted in JSON, transmitted to a server with the objective of invoking a specific function or procedure.</p>
        <p>For the purpose of evaluating the Besu blockchain, we selected and implemented a tool known
as Ethspam. This tool is specifically designed to generate a continuous stream of realistic Ethereum
JSON RPC queries. It is noteworthy that these queries are meticulously crafted to be read-only in
nature, signifying that they are not intended to induce any modifications to the state of the blockchain.
To comprehensively evaluate the Quorum blockchain, we opted to leverage a tool designated as
Chainhammer. By employing these aforementioned tools, we were able to conduct a comprehensive
and insightful analysis of the Besu and Quorum blockchains’ ability to process JSON RPC requests. This
in-depth exploration yielded invaluable insights into their performance characteristics, empowering us
to make informed decisions regarding their suitability for our specific requirements.</p>
      </sec>
      <sec id="sec-5-2">
        <title>5.2. Simulation of Energy Production from Photovoltaic Panels</title>
        <p>This section provides a detailed explanation of how the data regarding electrical energy produced
through photovoltaic panels was generated. We conducted simulations to determine the quantity of
electrical energy stored in the storage batteries and produced by the photovoltaic panels across diferent
time intervals throughout the day. The simulation builds upon a previous study that provides data on
the performance estimation of photovoltaic energy production [16]. Specifically, the data from this
research were generated using a specialized program designed to accept a list of objects categorized as
"producers" as input values. Within this framework, a "producer" object encompasses various parameters
that play a role in the simulation process, as outlined in Table 2. From a simulation perspective, each
"producer" object is characterized by a multitude of properties, including but not limited to, the nominal
capacity for electrical energy production of the system and the technological specifications utilized by
the inverters. Table 2 serves to delineate and elaborate on all pertinent parameters that are configurable
within the simulator framework for photovoltaic energy production.</p>
        <p>Producer Parameters
Battery Capacity
Battery Eficiency
Battery Type
Inverter Eficiency
Panel Eficiency
Nominal Power
Panel Orientation and Tilt</p>
        <p>Description
The maximum amount of electrical energy that can be stored in the
battery.</p>
        <p>The ratio of usable energy output to the total energy input into the
battery.</p>
        <p>The specific type or technology of the battery used in the system.</p>
        <p>The percentage of input electrical energy converted to usable output
energy by the inverter.</p>
        <p>The eficiency of converting sunlight into electricity by the
photovoltaic panels.</p>
        <p>The rated power output of the photovoltaic system under standard
test conditions.</p>
        <p>The angle and direction at which the photovoltaic panels are
installed relative to the sun.</p>
        <p>The figure 1 depicts the energy generated by a consumer over the course of a week. As illustrated,
the curve remains flat during nighttime hours and increases, reaching its peak at noon. It is noticeable
that on two particular days, the curve does not exhibit a Gaussian shape due to several hours of cloudy
skies, resulting in a reduction of electrical energy production by approximately 80%.</p>
        <p>Listing 1 showcases part of a larger program aimed at simulating energy production from photovoltaic
panels over the course of a week. The purpose of this specific segment is to generate data representing
the energy production at diferent times throughout the week. It iterates over each day, hour, and
minute, applying various conditions to simulate the energy production process, including fluctuations
due to weather conditions and time of day.</p>
        <p>Listing 1: energy production data
1 # G e n e r a t e e n e r g y p r o d u c t i o n d a t a
2 f o r d a y _ i d x , day in enumerate ( d a y s ) :
3 f o r hour in range ( d a y _ h o u r s ) :
4 f o r minute in range ( 0 , 6 0 , s a m p l i n g _ i n t e r v a l _ m i n u t e s ) :
5 i d x = ( d a y _ i d x ∗ d a y _ h o u r s ∗ 2 ) + ( hour ∗ 2 ) + ( minute / /
s a m p l i n g _ i n t e r v a l _ m i n u t e s )
6 i f hour in n i g h t _ h o u r s :
7 e n e r g y _ p r o d u c t i o n [ i d x ] = 0 # No s o l a r e n e r g y p r o d u c t i o n d u r i n g
t h e n i g h t</p>
      </sec>
      <sec id="sec-5-3">
        <title>5.3. Energy Token Exchange Smart Contract</title>
        <p>This section describes the smart contract employed specifically for the comparative analysis performed
in this paper. When energy is produced, the contract triggers the creation (minting) of energy tokens,
with their quantity incremented to reflect the energy generated. Conversely, when energy is consumed,
the contract reduces the quantity of tokens accordingly. This meticulous tracking mechanism ensures a
precise and up-to-date representation of the available energy within the network, enabling eficient
management and utilization of energy resources.</p>
        <p>Note that the smart contract, implemented in the projects to which this paper refers, implements
a more sophisticated management system designed to monitor and record the ownership of energy
as well as the exchange of energy among peers in the REC. Within the community each participant
is associated with one or more smart meters. Each participant and smart meter is associated with a
specific address, and only the owner of the energy token, or an address authorized, can manage the
token for example incrementing or decrementing its stored energy, or for example selling the token
thus transferring the token’s ownership from a peer to another one.</p>
        <p>Listing 2 presents the Solidity smart contract utilized in this article. The smart contract facilitates
the creation and management of tradable tokens representing energy units. Built upon the ERC721
standard, it enables users to interact with energy-based assets in a secure and transparent manner.</p>
        <p>With regard to the Token Minting and Energy Management aspects of the smart contract, it is worth
highlighting the following key points:
• The mint function serves as the cornerstone of token creation. It allows authorized entities
(governed by access control mechanisms) to mint new EnergyToken instances. These tokens are
assigned to designated addresses and carry an initial energy amount.
• The incrementEnergyAmount function caters to scenarios where additional energy needs to be
credited to a specific token. This functionality is crucial for situations like energy generation or
purchase.
• Conversely, the decrementEnergyAmount function facilitates energy consumption or transfer
by reducing the associated value for a particular token. It ensures a balance check to prevent
exceeding the available energy units.</p>
        <p>In terms of internal functionality and security, the smart contract utilizes two critical mappings to
facilitate eficient data management.</p>
        <p>• energyTokens: This mapping serves as the central repository for energy data. It associates each
token ID with its corresponding energy amount.
• _tokenExists: This internal mapping plays a critical role in ensuring data integrity. It eficiently
tracks the existence of tokens, preventing unnecessary checks and enhancing security.
• The _exists function serves as an internal helper, not directly accessible from outside the contract.</p>
        <p>It provides a secure way to verify token existence within the contract’s logic.</p>
        <p>Regarding the Benefits and Use Cases of this smart contract, they can be summarized in the following
key points:
• Representing and managing tradable energy units on a blockchain platform.
• Enabling secure and transparent energy transactions.</p>
        <p>• Facilitating eficient energy tracking and consumption monitoring.</p>
        <p>By leveraging the immutability and transparency of blockchain technology, this contract empowers the
development of innovative energy markets and fosters trust in energy-related transactions.</p>
        <p>Listing 2: Energy Token Exchange Smart Contract
1 // SPDX-License-Identifier: MIT
2 pragma s o l i d i t y ^ 0 . 8 . 2 0 ;
3 import "@openzeppelin/contracts/token/ERC721/ERC721.sol" ;
4
5
6
7
8
9
10 s t r u c t E n e r g y T o k e n S t r u c t {
11 u i n t 2 5 6 energyAmount ;
12 }
13
14
c o n t r a c t EnergyToken i s ERC721 {
u i n t 2 5 6 p u b l i c t o k e n I d C o u n t e r ;
mapping ( u i n t 2 5 6 =&gt; E n e r g y T o k e n S t r u c t ) p u b l i c energyTokens ;
mapping ( u i n t 2 5 6 =&gt; b o o l ) p r i v a t e _ t o k e n E x i s t s ;</p>
      </sec>
      <sec id="sec-5-4">
        <title>5.4. Enabling Energy Token Transactions</title>
        <p>This section elaborates on the script utilized for simulating token increment and decrement transactions
within the energy token system. Within our simulated environment, we posited that energy storage
operations within various batteries would occur at a frequency of one operation every fifteen minutes.
Each update from sensor readings triggers a transaction via the deployed smart contract to update the
token tracking energy.</p>
        <p>Technical Implementation: The script leverages the Web3.js library to interact with the deployed
smart contract. It simulates transactions by invoking the incrementEnergyAmount and
decrementEnergyAmount functions based on incoming sensor data. This approach ensures a realistic simulation of
energy token transactions in a real-world context.</p>
        <p>Benefits and Significance: This simulation tool serves as a valuable resource for developers to test
and refine the functionality of the smart contract. It aids in estimating the gas costs associated with
diferent transaction types and provides insights into the overall performance and scalability of the
energy token system.</p>
        <p>Future Enhancements: The script can be extended to accommodate additional parameters, such as
energy prices and transaction fees, thereby enhancing its utility. Furthermore, integration with other
blockchain-based applications can create a comprehensive energy management system.</p>
        <p>The transaction simulation script presented here ofers a valuable means of evaluating and optimizing
the functionality of the energy token system. By replicating real-world scenarios, it empowers developers
to enhance the system’s eficiency, security, and scalability.</p>
        <p>The frequency of energy storage operations should be replaced with the actual value utilized in the
system. The technical implementation details can be further elaborated upon to address specific project
requirements. Similarly, the benefits and significance of the simulation tool can be tailored to suit the
intended use case and target audience.</p>
      </sec>
    </sec>
    <sec id="sec-6">
      <title>6. Results</title>
      <p>In this research, we simulated two types of use cases to evaluate the performance and scalability of our
proposed blockchain-based energy trading platform.</p>
      <p>The first use case focused on a small-scale scenario with 20 prosumers (producers and consumers)
equipped with photovoltaic panels. These prosumers traded their surplus energy and battery storage
capacity using tokens on the blockchain. This scenario aimed to assess the feasibility and eficiency of
our platform in a realistic setting with a limited number of participants.</p>
      <p>The second use case aimed to test the limits of our technical solutions, implemented on both Besu
and Quorum blockchains. To achieve this, we employed open-source tools designed to simulate the
maximum number of transactions per second (TPS) that each blockchain can handle, as well as the
number of JSON-RPC requests that can be processed to retrieve information from the blockchain blocks.
By simulating a large number of concurrent users and transactions, we were able to identify potential
bottlenecks and performance limitations in our platform.</p>
      <sec id="sec-6-1">
        <title>6.1. Simulation with 20 Prosumers</title>
        <p>This section provides a detailed exposition of the results obtained from simulating electricity production
and consumption as transactions recorded on the two respective blockchains, Besu and Quorum, within
the energy community. The outcomes are meticulously captured in tabular formats and graphical
representations, meticulously designed to facilitate a comprehensive interpretation and analysis of the
data. Through these structured presentations, stakeholders can gain valuable insights into the dynamics
of energy production and consumption within the community, enabling informed decision-making and
strategic planning.</p>
        <p>The metrics we elected to measure in order to assess the capacity of the two blockchains to meet the
needs of an energy community are Transactions Per Second (TPS) and Requests Per Second (RPS). Both
TPS and RPS parameters are influenced by various factors, including the number of nodes utilized as
validators and the number of nodes used as RPC.</p>
        <sec id="sec-6-1-1">
          <title>6.1.1. Transactions Per Second</title>
          <p>Transactions Per Second (TPS), in the context of blockchain technology, refers to the measurement of
the rate at which transactions are processed and confirmed on a blockchain network within a given
timeframe, typically one second. It quantifies the network’s capability to handle a certain volume of
transactions within a specific duration. In simpler terms, TPS indicates how many transactions can be
executed and recorded on the blockchain per second. It’s a crucial metric for evaluating the scalability
and performance of a blockchain network. Higher TPS values generally imply that the network can
handle more transactions eficiently, while lower TPS values may indicate limitations in scalability and
processing speed. Achieving high TPS is often a key objective for blockchain developers and network
operators, especially in applications where real-time transaction processing is essential, such as financial
transactions or supply chain management.</p>
        </sec>
        <sec id="sec-6-1-2">
          <title>6.1.2. Requests Per Second</title>
          <p>Requests Per Second (RPS), in the context of blockchain and JSON RPC (Remote Procedure Call) requests,
refers to the number of requests sent to the blockchain network per second. In a blockchain system,
JSON RPC is often used as a method for clients to communicate with the blockchain network. These
requests can include various actions such as querying data, sending transactions, or interacting with
smart contracts. RPS measures how many of these requests the blockchain network can handle within
a one-second time frame. It indicates the network’s capability to process incoming requests eficiently
and in a timely manner. Higher RPS values typically indicate a more scalable and responsive blockchain
network, capable of accommodating a larger volume of user interactions.</p>
        </sec>
      </sec>
      <sec id="sec-6-2">
        <title>6.2. Stress Test Results under Maximum Load</title>
        <p>The results section pertaining to the stress test is divided into two distinct parts. The initial part delves
into the examination of the system’s utmost capability in managing JSON RPC requests. Subsequently,
the latter part scrutinizes the system’s maximum capacity in handling the volume of transactions per
second (TPS).</p>
        <sec id="sec-6-2-1">
          <title>6.2.1. Evaluating Besu’s Performance under Stressful JSON RPC Loads using Ethspam</title>
          <p>To assess the ability of Besu to handle JSON RPC requests, we utilized the ethspam library, available at
the following address: https://github.com/shazow/ethspam. Ethspam generates a continuous stream of
authentic read-only Ethereum JSON RPC queries, centered around the latest block with a certain degree
of random variance. The most recent state is refreshed every 15 seconds, ensuring continuous operation
without data becoming outdated. On average, the Ethspam application produces an approximate output
of 500,000 lines or 120 megabytes of data per second on the designated computer desktop utilized for
our testing purposes. In the performance evaluation, Hyperledger Besu demonstrated a robust ability
to handle high transaction volumes of JSON RPC requests. When subjected to a simulated workload of
100,000 JSON RPC requests, Besu was able to process and respond to an average of 2,201.01 requests
per second. This translates to processing over two thousand transactions every second, showcasing
Besu’s potential for high-throughput applications.</p>
        </sec>
        <sec id="sec-6-2-2">
          <title>6.2.2. Evaluating Quorum’s Performance under Stressful JSON RPC Loads using</title>
        </sec>
        <sec id="sec-6-2-3">
          <title>Chainhammer</title>
          <p>To evaluate Quorum’s capacity to process JSON RPC requests, we employed the Chainhammer tool
(https://github.com/drandreaskrueger/chainhammer). Chainhammer is an open-source performance
benchmarking tool specifically designed for testing blockchain platforms like Quorum. It functions
by simulating a high volume of JSON RPC requests, allowing us to gauge Quorum’s ability to handle
real-world workloads eficiently. Quorum demonstrated a marginally higher processing capacity than
Besu under identical test conditions. Quorum achieved an average processing rate of 2,305.82 requests
per second when bombarded with 100,000 JSON RPC requests.</p>
        </sec>
        <sec id="sec-6-2-4">
          <title>6.2.3. Stress Testing Besu TPS with Hyperledger Caliper</title>
          <p>To determine the maximum transaction throughput of the Besu blockchain under the setup described
in Section 5.1, we employed the Hyperledger Caliper tool. Hyperledger Caliper is an open-source
performance benchmarking framework designed to evaluate the performance of blockchain platforms.
It provides a comprehensive suite of tools and methodologies for conducting performance tests, enabling
developers to assess the scalability, latency, and overall throughput of blockchain networks. We identified
our capacity to process transactions per second, supported by the following data: 334 transactions per
second for the Besu blockchain, with a standard deviation of 20.</p>
        </sec>
        <sec id="sec-6-2-5">
          <title>6.2.4. Stress Testing Quorum TPS with Apache JMeter</title>
          <p>To evaluate the maximum transaction processing capacity of the Quorum blockchain under the
configuration detailed in Section 5.1, we utilized the Apache JMeter tool. Apache JMeter is an open-source
load testing tool used for performance testing of various applications, including blockchain platforms.
It allows for simulating a high volume of concurrent requests, enabling us to assess Quorum’s ability to
handle real-world transaction loads eficiently.</p>
          <p>The results for analyzing the maximum load capacity that the two blockchains can handle in terms
of transactions per second and requests per second are synthesized through graphs and tables [17]. In
particular, Figure 2 illustrates four box plots: two for the maximum TPS load that the two blockchains,
Quorum and Besu, can handle, and two for the maximum number of requests that the two blockchains
can manage.</p>
          <p>Table 3 presents statistics regarding the data collected for the two blockchains when subjected
to stress tests using the tools listed in Table 1. Among the reported values are the means, standard
deviations, quartiles (including Q1, Q2, and Q3), as well as the minimum and maximum values.</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-7">
      <title>7. Discussion</title>
      <p>The outcomes of this investigation can be partitioned into two distinct parts.</p>
      <p>Specifically, in the initial part, we conducted a simulation involving a mere 20 prosumers. The
statistical analysis yielded a t-statistic of -0.1138 and a p-value of 0.9095. In this study, our objective was
to compare the transaction volumes between the BESU and Quorum networks. To gauge the significance
of any disparities observed, we rigorously executed a statistical examination. However, upon thorough
evaluation, we found that the calculated p-value associated with the comparative analysis fell short
of meeting the predetermined threshold for statistical significance, typically set at 0.05. This outcome
suggests that there exists insuficient evidence to warrant the rejection of the null hypothesis. The null
hypothesis posits that there is no discernible distinction in transaction volumes between the BESU and
Quorum networks. Consequently, based on the empirical evidence analyzed in this investigation, we
cannot assert with confidence the presence of a statistically significant variance in transaction volumes
processed by these two blockchain networks. In the scenario we tested, involving energy communities
with only 20 simulated users, we didn’t observe any diferences.</p>
      <p>Subsequently, utilizing dedicated simulation tools, we conducted an in-depth analysis of the maximum
transactional capacity of Besu and Quorum blockchains, considering the software and hardware
configuration employed in our simulation. The analysis revealed significant diferences between Besu and
Quorum in terms of Transactions per Second (TPS) and Requests per Second (RPS). Specifically, within
the hardware and software configuration described in section 5, the Quorum blockchain demonstrated
superior performance compared to Besu. The statistical analysis using a t-test yielded a T-Statistic of
-47.3566 and a P-Value of 0.0. A P-Value of 0.0 indicates a statistically significant diference between Besu
and Quorum’s performance in terms of TPS and RPS within the context of our simulation environment.
Therefore, we can confidently reject the null hypothesis, which stated that there is no significant
diference between the two blockchains. This finding strongly suggests that Quorum outperforms Besu
in our specific hardware and software configuration.</p>
    </sec>
    <sec id="sec-8">
      <title>8. Conclusion</title>
      <p>In this study, we conducted simulations of two distinct scenarios to evaluate the eficacy of our
blockchain-based technical solutions in facilitating the management of energy communities [18].</p>
      <p>The initial scenario involved a small-scale setting comprising 20 prosumers (entities both producing
and consuming energy) equipped with photovoltaic panels. These prosumers engaged in trading surplus
energy and battery storage capacity through blockchain-based tokens. This scenario was designed to
gauge the practicality and efectiveness of our platform within a realistic context featuring a limited
participant pool.</p>
      <p>The subsequent scenario aimed to stress-test our technical solutions, deployed on both Besu and
Quorum blockchains. To accomplish this, we utilized open-source tools tailored for simulating the
maximum transaction throughput per second (TPS) and the volume of JSON-RPC requests processed
for blockchain block data retrieval. Through simulating a significant volume of concurrent users
and transactions, we aimed to pinpoint potential bottlenecks and performance constraints within our
platform.</p>
      <p>Our findings confirm that simulating an energy community scenario involving only 20 producers,
trading energy through tokens, shows no performance diference in terms of TPS and RPS between the
two blockchains. However, when considering implementation for a much larger-scale environment, the
Quorum solution appears to be more eficient in terms of both TPS and RPS compared to Besu. The results
of these simulations provided valuable insights into the scalability and performance characteristics of
our blockchain-based energy trading platform. This information will be used to optimize the platform
and ensure its ability to handle a large number of users and transactions in a real-world deployment.</p>
      <p>This analysis helped us to identify potential challenges and opportunities associated with the adoption
of our platforms BESU and Quorum. We believe that our findings will be valuable for researchers,
developers, and policymakers who are interested in exploring the potential of blockchain technology for
energy communities. Future research could delve deeper into the comparative analysis by extending it to
diferent hardware and software configurations to obtain a broader mapping of the relative performances
of Besu and Quorum.</p>
    </sec>
    <sec id="sec-9">
      <title>9. Acknowledgement</title>
      <p>This work was partially funded under the National Recovery and Resilience Plan (NRRP), Mission 4
Component 2 Investment 1.5—Call for tender No. 3277 published on 30 December 2021 by the Italian
Ministry of University and Research (MUR) funded by the European Union-NextGenerationEU. Project
Code ECS0000038—Project Title eINS Ecosystem of Innovation for Next Generation Sardinia— CUP
F53C22000430001-Grant Assignment Decree No. 1056 adopted on 23 June 2022 by the Italian Ministry
of University and Research (MUR). This work was partially funded under the National Recovery and
Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.3—Call for tender No. 1561 of 11.10.2022
of Ministero dell’Università e della Ricerca (MUR) funded by the European Union–NextGenerationEU,
Project code PE0000021, Concession Decree No. 1561 of 11.10.2022 adopted by Ministero dell’Università
e della Ricerca (MUR), CUP F53C22000770007, according to attachment E of Decree No. 1561/2022,
Project title “Network 4 Energy Sustainable Transition–NEST”.</p>
    </sec>
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