A common vision for the future of the nation’s energy grid involves homeowners selling unused power generated from rooftop solar panels to others in their communities, and working together to help ensure the reliability, resiliency, and security of the power grid everyone uses.
Sounds great in theory. But how can the grid manage such complex energy transactions at scale?
Several emerging solutions to this opportunity rely on blockchain technology. Researchers at the National Renewable Energy Laboratory (NREL) are evaluating the use of blockchain for transactive energy using hardware in the laboratory’s Energy Systems Integration Facility (ESIF) and it may reshape the world of electric systems operation.
“Distributing grid operational decision-making is revolutionary,” said Dane Christensen, a mechanical engineer in NREL’s Residential Buildings Research Group and a principal investigator on a blockchain pilot project.
“It’s really like somebody in the 1980s expounding on the economic opportunity of the Internet. Everyone would have laughed at you.
That’s kind of what’s happening right now with blockchain applications – the foundational tools for another technology revolution are emerging, and this could be one of them.”
The Potential for Blockchain in the Energy Sector
For the uninitiated, blockchain serves as a distributed digital record of actions agreed and performed by multiple parties.
Blockchain’s primary value is providing mathematical proof about the state of data, so that different parties to a transaction can agree on the outcome even if they do not know or trust each other.
Though commonly associated with cryptocurrencies such as Bitcoin, blockchain technology can be used with virtually any type of transaction involving digital ownership in real time.
These technologies rely on established cryptography and consensus mechanisms to ensure transactions remain secure, and an entire industry has emerged to apply blockchain technology in resolving real-world challenges.
Potential opportunities abound for the use of blockchain in the energy sector. The Congressional Research Service last year noted increasing interest among producers of distributed energy resources (DERs) – such as rooftop solar – to sell electricity to neighbors. Congress’ public policy research arm predicted that if this approach proves “practical and economical, blockchain technology could alter the manner in which electricity customers and producers interact.”
Today, utilities use complex software platforms called an energy management system (EMS) and advanced distribution management system (ADMS) to manage the demand, supply, and reliable delivery of electricity on the power grid.
But it is difficult to scale EMS and ADMS to interoperate transactions between thousands of homes, let alone the millions of connected devices in use in those homes.
“When you have hundreds of thousands or millions of devices out there that want to interact, you face a significant trust challenge,” said Tony Markel, a senior engineer in the Energy Systems Cyber-Physical Security Research Group at NREL.
“Trust between devices can only be achieved through methods that verify and enable proof that each system does what it said it was going to do. With blockchain, we may have a path to achieve secure, trusted communications between players without a need for central control.”
NREL Researchers Evaluate a Peer-to-Peer Blockchain
This required two blockchain transactions: a secure transmission of data about the amount of energy generated, and a payment to the seller.
Central to this research is an NREL-developed software solution called foresee. The software uses homeowners’ energy preferences – such as the temperature of their home, or their energy budget – to control connected appliances within the home.
In the blockchain experiment, foresee alerted the second home when it would be cheaper to buy renewable energy from its neighbor rather than paying the utility’s charges, then used a digital currency to complete the transaction.
The demonstration showed the ability to automatically match energy generation and demand between these two homes.
“There’s a lot of talk and buzz out there about blockchain but very little documentation,” said Dylan Cutler, principal investigator on the project.
“This project was a necessary first step in this field – for me, at least, and I think the lab in general – to get some comfort with the technology.”
The results highlighted the path for future research. Notably, Cutler pointed out, the use of blockchain in the energy markets will require an examination of grid reliability and resiliency and cybersecurity concerns.
One area Cutler’s initial research did not consider was the role a utility would play in peer-to-peer energy transactions, and that is something he said a future study must consider.
“I think we just have to recognize that utilities own our grid infrastructure and are on the hook to deliver and maintain a reasonable power quality,” he said. “If you were to sell power to your neighbor, it would be using the utility’s assets. Somehow, the utility needs to be aware and maybe compensated for that.”
Cutler, a senior researcher in NREL’s Integrated Applications Center, said the emergence of blockchain technology requires a newly designed market. While the common assumption of blockchain is the end user holds sway over the distributed control of energy, in reality it is likely that electric power utilities will at minimum be responsible for coordinating these neighborly transactions. “That’s the logical entity that would step in and operate this,” he said, “but the nature of blockchain enables it to not be a single party. It doesn’t have to be a utility.”
Community-Scale Energy Collaboration
NREL is building on this prior work to study the benefits for building owners and utilities. Using a blockchain-based market technology, the research centers on the operation of the electrical grid as homes and businesses continue to adopt rooftop solar generation, battery storage, electric vehicles, and smart appliances.
The laboratory’s partners are Exelon Corporation, a utility based in Chicago, and Energy Web Foundation, which develops open source blockchain software solutions.
Christensen and Sivasathya Pradha Balamurugan, NREL’s co-principal investigators on the project, said the use of blockchain would allow increased coordination between utilities and customers to achieve mutual benefits.
Electricity generated from renewable resources such as solar and wind that customers cannot use can be diverted to the grid, but there are limits. Feeders – which carry voltage from a substation to transformers – were not designed for the bidirectional flow of electricity.
“There will soon be feeders in the U.S. where if you plug in one more electric car, you could damage transformers or activate safety cutoffs because we’re reaching the limits of the capacity of the distribution grid,” Christensen said.
“Utilities are very interested in how to manage electric service without having to up-size all the grid equipment. Coordination of buildings’ energy use is a way to keep costs down, make better use of distributed generation, and improve reliability of the power grid.”
Using NREL’s ESIF systems, the research team is examining how blockchain-based energy markets can allow buildings to coordinate within a distribution feeder, under appropriate constraints defined by the utility.
In particular, the team will explore how a blockchain-based approach to digital identity can help utilities verify the attributes and the operations of distributed energy resources in their territory.
The project goal is to allow high levels of solar and flexible loads to be installed in buildings, while eliminating the occurrence of energy backfeed into the bulk power grid. If successful, this will allow building owners and utilities to work together to accelerate adoption of advanced energy technologies. It may also unlock new opportunities for customers with solar or storage assets to earn money or lower their bills by providing grid services.
By relying on blockchain, Christensen said, utilities could integrate many different types of DER with core operational tools (such as EMS and ADMS software) securely and efficiently. “Traditionally, integrating new resources into the grid comes at a substantial cost for a utility. A large part of that cost is driven by custom and manual processes for different DER types. Every feeder is different. Every home is different. As more renewables are adopted, as more electric vehicles are adopted, continuous expert engineering has to be done.”
The engineering to ensure one feeder operates efficiently and effectively in balancing supply and demand does not necessarily translate to another feeder. “What blockchain allows,” Christensen said, “is a scalable solution that you can easily set up on another feeder because it can be self-customizing.”
NREL and Exelon said a utility can use the findings of the new blockchain research to make a case for allowing a pilot project. “The virtual pilot occurring at NREL is as close as possible to installation on a live grid. The project will establish customer benefits, utility cost/benefit, and help to de-risk the blockchain market solution prior to a deployment.”
Other National Laboratories Collaborate with NREL
NREL has also embarked on a two-year effort with other national laboratories to accelerate the use of blockchain in the energy sector.
A new collaborative effort called Blockchain for Optimized Security and Energy Management (BLOSEM) intends to develop the architecture and infrastructure so that utilities can safely explore the technology.
“The interest specifically around blockchain is knowing that utilities need to be able to move faster on the integration side of things,” Markel said. “There’s an expectation that this could provide them some consistency in outcomes and knowledge that accelerates the adoption process.
There are still quite a few unknowns: How do you make this work and what information sets will stakeholders need to share?
Would the blockchain systems help highlight an untrusted device that’s been compromised by a cyber attack?
It’s a good space for the lab to really spend the time and effort to clarify those unknowns so we can guide necessary future developments.”
NREL’s initial role in BLOSEM expands on the laboratory’s previous accomplishments, with additional simulations planned to expand the use of blockchain. The National Energy Technology Laboratory is the lead organization on the project, with Ames Laboratory, SLAC National Accelerator Laboratory, and Pacific Northwest National Laboratory also part of the research team. The Grid Modernization Laboratory Consortium is funding BLOSEM. U.S. Department of Energy offices funding this project include the Office of Fossil Energy, Office of Nuclear Energy, and Office of Electricity Delivery and Energy Reliability.
“From a national lab perspective,” Markel said, “we are in a good position to lead energy and security related application of blockchain technologies. Our work should offer consistent metrics relevant to utilities on leveraging blockchain to enable millions of systems to behave in a trusted manner. That’s a big chunk of what we need to demonstrate along with resolving some key unknowns.”
Blockchain Technology Connects Us to the Future
Juan Torres, NREL’s associate laboratory director for energy systems integration, estimates it will take 5-10 years before blockchain technology solidifies its place in the energy sector. The mechanisms allowing neighbors to buy electricity from each other are not operational today.
“There is a significant amount of communication that’s required across the users, the folks who want to buy the energy,” Torres said. “There’s communication and negotiation between the various devices.
And somewhere along the way, we have to make sure those micro transactions won’t cause instabilities on the larger grid. Utilities need to be able to get information about these transactions. It’s a system with a lot of moving electrons is the way I would describe it.”
Smart grids are currently advancing technologically at a very fast pace by leveraging the benefits offered by Wireless Sensor Networks (WSNs) and the Internet of Things (IoT).
They offer optimization in energy production and consumption by the adoption of intelligent systems that can monitor and communicate with each other [1,2,3].
Automation of the smart sensor-based metering system by using Advanced Metering Devices (AMI) leads to a lesser requirement of manpower and more accuracy. Thus, by making the grid more intelligent, efficient energy utilization is achieved [4,5].
Smart grids also promise more efficient tapping of renewable sources of energy by offering technological support for the transfer of energy between local energy producers and consumers.
The consumers who can harvest renewable sources of energy such as sunlight using rooftop solar panels can become producers-cum-consumers (prosumers) by selling their surplus energy either to neighboring consumers or to the grid.
This promotes consumers to utilize renewable sources of energy . Since the energy demand is ever-growing and there are multiple sources of energy, the need for a decentralized energy management system has arisen .
The system should be able to manage the individual transactions between the users as well as between the user and the grid without any tampering of data or loss of information. Integrating distributed renewable energy resources whose power generation is highly fluctuating makes it very challenging for the utilities to estimate the state of the system.
Some works [8,9,10] have proposed novel Kalman filter-based approaches for accurate microgrid state estimation and control for the smart grids. Their models encourage consumers to use environment-friendly renewable energy sources which will lead to many benefits such as line-loss reduction, reliability, energy efficiency, etc.
The authors of  discussed energy demand reduction of the utilities and consumers and smart energy management while considering the ever-growing renewable energy integration.
Another issue that hinders an efficient grid management system is the requirement of third parties for the supply and distribution of energy. Third-party involvement always increases the cost of operation drastically and paves the way for erroneous transactions, intentionally or otherwise. This is where blockchain offers a promising solution to these existing issues of the smart grid [12,13].
The adoption of blockchain technology allows the grid network to decentralize its operations. That means the decision making and the transaction flows do not need to be channeled through a centralized system that is inclusive of third parties, e.g., mediators, banks, etc.
The record of transactions is stored in all or selected nodes involved in the operation of the network depending on the type of blockchain used [14,15]. The transactions of buying and selling of energy across users no longer needs to go through the procedures of a bank but rather can be done through a computer program by validating the required pre-determined clauses of the transaction .
Blockchain technology among various other benefits helps in setting up real-time energy markets and identity preserving transactions at much lower costs due to a simplified trading framework [17,18].
The computation and power consumption of IoT devices are important challenges restricting the application of blockchain in IoT and smart grid. The authors of  proposed a decentralized on-demand energy supply architecture for miners in the IoT network, using microgrids to provide renewable energy for mining in the IoT devices.
This paper identifies some of the various scenarios in which blockchain can be incorporated in the smart grid, and discusses the various technological aspects about each scenario.
The main contributions of this paper are:
- We discuss major applications of blockchain in smart grids, giving details such as blockchain architecture, sample block structure and blockchain-related technologies employed in each application area.
- A table summarizing these application areas with important technical details is also presented after a discussion of the application areas.
- We then discuss commercial implementations of blockchain in the smart grid.
- We also discuss existing challenges for incorporating blockchain into the smart grid and present some future research directions.
The rest of the paper is organized as follows. Section 2 gives a brief overview of blockchain technology. In Section 3, important application areas of blockchain in the smart grid are discussed. Section 4 summarizes several commercial implementations of blockchain in the energy sector. In Section 5, practical challenges in the incorporation of blockchain into the smart grid are discussed. Section 6 suggests some future research directions. Finally, the paper is concluded in Section 7.
Blockchain is a decentralized ledger meant for keeping a record of the various transactions carried out in the network right from the beginning of the chain. The ledger is shared among different nodes (also referred to as peers) that participate in the network, with each peer having its copy of the ledger.
Each block in the chain is connected to the previous one using cryptographic techniques, which makes the system secure and resistive to malicious attacks and malpractices, as illustrated in Figure 1. Each node can check for the validity of the transactions and reach a consensus before adding the block to the blockchain, thus providing a high level of transparency and reliability.
Composition of Blockchain
Each transaction in a blockchain is verified by the participating nodes using a consensus algorithm and, if a consensus is reached upon its validity by the nodes, the transaction data are stored into structures called blocks.
Mining is the addition of the blocks into the blockchain while the Miners or the Mining Nodes are the nodes involved in this process. A cryptographic hash function  links any two adjacent blocks in the blockchain, with the hash of the previous block stored in the current block.
To carry out a successful attack, the attacker trying to modify a particular block in the blockchain has to ensure that all the following blocks are also modified. Since the hash of the current block is stored in the next block, modifying any field of the current block will also modify its hash.
Thus, the older the target block is, more challenging it is for an attacker to modify and update the block and all the succeeding blocks until the newest block in the blockchain.
Furthermore, the attacker also has to ensure that no new block has been added into the blockchain by the time his changes are reflected in the blockchain. This requires a much higher processing and hashing capability on the attacker’s end compared to the combined capability of all the miners.
Therefore, such an attack on the blockchain network remains economically quite infeasible. In addition, since a copy of the complete blockchain is available with each participating node of the network, any malpractice such as modification of a block of the blockchain can be easily detected.
These cryptographic security techniques thus provide data immutability to the blockchain. Each block essentially comprises of a block header and a block body. The block header contains various fields such as the previous hash, timestamp, etc. The timestamp indicates the time of the creation of a block.
Version denotes the type and format of data contained in the block while the Merkle root hash is the combined hash of all the transactions that have been added into that block. Merkle trees are generated by iteratively hashing pairs of transactions until there is only one hash value left.
The single hash value is called the Merkle root. Merkle root is the digital fingerprint of all the transactions stored in a particular block. Using a Merkle root, a user can securely and efficiently verify the presence of a particular transaction in a block.
A nonce is an arbitrary number used by the mining nodes to change the block’s hash value to satisfy the consensus criterion of a blockchain. The block body comprising of the transaction information related to the block can be divided into two parts.
The first part of the block stores information about the transactions (amount, date, time, etc.), whereas the other part stores information about the participants of the transactions. All blocks are connected to form a chain having information about the transaction history of the whole network and are shared with the whole network [21,22,23,24].
Classification of Blockchains
Blockchains are generally classified into three types, namely public, consortium and private blockchain. A comparison of these three types based on different parameters is summarized in Table 1.
Classification of blockchains [25,26,27,28,29,30,31].
|Parameter||Public Blockchain||Consortium Blockchain||Private Blockchain|
|Receptivity||Fully open||Open to some nodes||Open to a person/entity|
|Access to Write||Anyone||Specific nodes||Internally controlled|
|Access to Read||Anyone||Anyone||Open to the public|
|Speed of Transaction||Low||High||Extremely high|
|Decentralization||Fully decentralized||Less decentralized||Less decentralized|
Applications of Blockchain in Smart Grid
Figure 2 lists important applications of blockchain in the smart grid scenario. Based on the existing surveys and reviews on blockchain applicability in IoT [32,33,34,35], in this paper, we focus on these five important application areas in smart grids where blockchain technology has been extensively researched.
Each of these application areas is discussed below giving details of the blockchain architecture employed, the structure of a sample block and the different blockchain technologies used.
Peer-To-Peer Trading Infrastructure
A major drawback in the existing grid networks is the lack of security regarding the transactions caused by the involvement of mediators and other third parties. This hierarchical organizational trading structure of the grid leads to heavy operating costs with low efficiency of operation [36,37].
On the other hand, a blockchain-based trading infrastructure offers a decentralized platform that enables the Peer-to-Peer (P2P) trade of energy between consumers and prosumers in a secure manner.
The identity privacy and security of transactions is higher in the decentralized platform compared to the traditional system. The P2P energy trade finds purpose in many applications including the Industrial Internet of Things (IIoT) and enhances the possibility of developing micro-grids leading to sustainable energy utilization [38,39].
The UK based Energy Networks Association has declared the plan to invest 17 billion Euros in the local energy markets using the smart grid . Various aspects of P2P energy trade using blockchain are discussed below.
Based on the various state-of-the-art research works surveyed on P2P energy trading infrastructure using blockchain, the blockchain architecture for a typical P2P energy trading system can be shown as in Figure 3.
This architecture is based on the reference model used in , in which the authors used a consortium blockchain-based secure P2P energy trading system. A comparison of several such research works is shown in Table 2.
Depending on the market scenario, the required computational power and the speed of transactions, the decision regarding the choice of blockchain type to be used can vary.
Table 2 – Comparison of state-of-the-art research papers on P2P energy trading using blockchain.
|Ref.||Cost and Energy Optimized||Optimization Applied||Secure against Attacks||Security Analysis||Scalable||Performance Analysis|
A public blockchain gives a high level of transparency by providing a copy of the distributed ledger to each node, and the ability to perform consensus and validation of data. However, the disadvantage comes in the form of energy consumption and performance.
A consortium blockchain, on the other hand, allows only a set of pre-authorized nodes to handle the distributed ledger or the transaction database. Only these authorized nodes are allotted high computational capabilities required to solve the consensus algorithm thereby reducing the overall power consumption and facilitating faster transactions.
The authors of  proposed a consortium blockchain platform for facilitating a secure P2P system for energy trade in IIoT, called energy blockchain.
The different energy nodes comprising of small scale consumers, industrial consumers, electric vehicles, etc. are given the flexibility to choose their roles as buyers/sellers or idle nodes can initiate transactions according to their requirement.
A record of these transactions is stored and managed by a special authorized set of entities called Energy Aggregators (EAGs).
In the case of P2P energy transfer, a typical block in the blockchain network, as shown in Figure 4, consists of data structures that include information regarding the amount of energy used and the timestamp indicating the usage of energy usually dealing with a particular transaction . The number of structures and the data included depends on the architecture adopted.
In a consortium blockchain with predefined processing and consensus nodes, the block structure consists of the Block ID for unique identification; Header, which is hashed with a Secure Hash Algorithm (SHA); Lock Time, which indicates the time of addition of that particular block into the network; and the transactions.
Each transaction is generated when the buyer requests energy from the transaction servers of the supervisory nodes. The transaction part of the block structure consists of data specific to each transaction such as Transaction ID (TID), Meter ID (MID), Amount of Energy Requested (AER), Amount of Energy Granted (AEG) for the requesting buyer by the supervisory nodes based on the available energy from the sellers, Energy coins Transferred (ET) by the buyer for the transaction, Digital Signature of the Seller (DSS) indicating a successful transaction, and Digital Signature of the Processing node (DSP) indicating validation of the transaction. It also includes timestamps indicating Time of Request (TR) and Time taken for Transaction (TT).
- Virtual currency: Using blockchain, a virtual currency can be created for representing each unit of electricity. This system is highly useful in situations where renewable energy is generated at the prosumer’s end. Surplus energy available to the prosumer can be sold by engaging in transactions with other peers within the blockchain network and transferring this electrical energy into the grid. The prosumer can earn virtual currency for the energy sale at a specified price while the consumers with deficit can buy energy for their requirement with the virtual currency. The true identity of both the buyer and the seller do not need to be disclosed in such transactions using virtual coins [39,46]. Further, incentive schemes can be introduced for the promotion of renewable energy. A set of peers who contribute the most to the trade of renewable energy can be chosen by monitoring the transaction history from the blockchain ledgers and rewarded with virtual currencies.
- Credit-based transactions: Since there is some latency in the validation and addition of transactions into the blockchain, which in turn delays the release of virtual currency for the respective user, users might face a shortage of virtual currency temporarily. A credit-based transaction system helps such users in purchasing the required energy without actual possession of virtual currencies at that moment. Li et al.  utilized a credit-based payment scheme where each node is allotted an identity, a set of public and private keys, a certificate for unique identification, and a set of wallet addresses upon a legitimate registration onto the blockchain. Upon initialization, the wallet integrity is checked and its credit data are downloaded from the memory pool of the supervisory nodes (which store records on credit-based payments). The request from each node for the release of credit-based tokens is validated by the credit bank managed by the supervisory nodes and released if the requesting node meets the specified criteria. These tokens which are then transferred to the wallet of the node can be used to buy the required energy from other selling nodes [39,47].
- Smart contracts: These are computer codes consisting of terms of agreements under which the parties involved should interact with each other. They are finite state machines that implement some predefined instructions upon meeting a particular set of conditions or certain specified actions. Smart contracts associated with the smart meters in the grid are deployed in the blockchain. They ensure secure transactions by allowing only authentic data transfers between the smart meters and the supervisory nodes and report if any unauthorized and malicious tampering of data has occurred [47,48].
Power Generation and Distribution
Numerous cyberattacks on smart grids have been undertaken in the past where the malicious attackers have used various methods such as Denial of Service (DoS), Data Injection Attacks (DIA), etc. to manipulate data and gain control in the grid [68,69].
This has resulted in complications such as regional power outages and even complete blackouts . Incorporating blockchain into the power generation and distribution systems help in the prevention of data manipulation since one of the prime characteristics offered by the blockchain system is its ability to ensure data immutability.
Figure 9 shows how a blockchain system can be incorporated into a power generation station with a Single Machine Infinite Bus (SMIB) system and its distribution networks. This framework is created based on the architectures discussed in other works on power generation and distribution using blockchain [66,71].
An SMIB is constituted by a synchronous generator G, which is connected to the infinite bus through a reactance Z; a load, which is fed through a load switch SL; a Power System Stabilizer (PSS) used for damping the generator’s electro-mechanical oscillations to protect the shaft line and to provide grid stabilization; and a control switch SC for the PSS, which takes its input from the load switch.
A cyber attacker can use a suitable attacking scheme to modify the conditions of the switches resulting in the removal of load from the generator and leading to sudden transition in the terminal voltages to very high values.
Since the control switch, SC to PSS, is tampered with, automatic voltage regulation is rendered unresponsive and damping of the oscillations does not occur. This leads to shaft damage and loss of synchronization in the target generator.
This can be avoided by incorporating the blockchain into the power generation system . The time-stamped values of each switch state and the target generator can be stored as data in the blocks.
Specific nodes can be given the privilege to validate and mine the data into the blocks. In the event of an attack, violation in the current state of each switch should be reported to the blockchain.
A smart contract in the metering device would then identify the violation and maintain the previous terminal value of the target generator by enforcing PSS to damp the oscillations.
The block body, as shown in Figure 10, includes measurements, switch states, violations and timestamp. The measurements part of the block includes the frequency, voltage, and current generated by the system.
Switch States store the states of the switches SL, SC, and PSS and the measured value of the target generator G. The failed status of the switches as reported by the respective metering devices is stored in the violations part of the block. The timestamp indicates the time instant of the measurement. This data is further utilized by the smart contract to take the necessary action.
Commercial Implementations of Blockchain in the Smart Grid
One of the foremost applications of blockchain in the smart grid is to incorporate virtual currencies for payments. The first company to accept Bitcoin for payment of energy bills was BASNederland .
This inspired several other companies to come up with cryptocurrency-based solutions for billing and metering, and several of them providing incentives for users making payments using cryptocurrency instead of those using fiat currencies [77,78].
Meanwhile, some other companies such as the South Africa based startup Bankymoon are developing smart meters with integrated payments using Bitcoin . The Netherlands based companies Spectral and Alliander have developed a blockchain-based token for energy sharing called Jouliette .
This token allows the P2P transaction of electricity through spending the energy tokens from their e-wallets. Another company, PowerLedger, an Australia based startup, developed a blockchain-based platform for P2P renewable energy transfer between residential prosumers and consumers .
The platform makes use of a smart contract-based system called POWR to enable the transfer of tokens called Sparkz. The company has demonstrated its ability in saving significant revenue for the users and supplying additional incentives for renewable energy producers.
The most significant implementation of blockchain in P2P decentralized energy trading and creation of a local marketplace is the Brooklyn microgrid. It was launched by the US energy firm LO3Energy along with ConsenSys, a Blockchain company .
The first trial of the project, which was carried out with five prosumers and five consumers, marked the first-ever recording of energy transactions using blockchain. Ethereum-based smart contracts were used to architect the platform, which facilitated the consumers to buy surplus renewable energy from the prosumers through a token-based transaction system.
The surplus energy tapped through the rooftop photovoltaic (PV) panels by the prosumers is converted into tokens by the smart meters installed in their houses, which can be directly used for trade in the energy market.
This platform records the mode of transaction in energy units or tokens as per the requirement of the user. The ledger stores, in chronological order, details about each transaction, such as the parties involved, the amount of energy consumed/sold and the related contract terms.
The future developments in the Brooklyn microgrid system include assigning the users with the ability to choose from the prospective buyers/sellers the required energy, among other privileges such as the ability to decide the percentage of energy share needed to buy from prosumers and the main grid. A bidding system will be used in which renewable energy will be sold to the highest bidder.
A mobile application is also being developed to provide users with easy means of interaction with the platform. Such projects will change the face of energy transactions in the coming future .
ShareandCharge is a blockchain-based platform developed jointly by InnogyMotionwerk, a subsidiary of German energy conglomerate RWE, and a blockchain firm Slock. This platform allows P2P energy trading among EVs and the private charging stations .
The users can use their e-wallets to know about the real-time prices and carry out transactions on this public Ethereum-based platform, which automatically manages certificates and billing. JuiceNet is yet another blockchain-based platform deployed by a company called eMotorwerks in California for leasing out charging piles to EV drivers for some time .
The platform maintains a record of the transactions and allows the owner of the charging pod the required payment. Moreover, JuiceNet provides a mobile application for the owners of the EVs to locate a charging pile from among the enlisted charging piles in the neighborhood.
Challenges for Blockchain Incorporation into Smart Grid
Transactions in a blockchain increase on a day-to-day basis, which calls for heavy storage capabilities to accommodate the ever-growing number of transactions. Currently, the storage for Bitcoin has exceeded 200 GB while that for Ethereum has reached about 1 TB.
Even though a considerably high number of transactions are being carried out using Bitcoin, the processing rate of data into blocks in a blockchain is estimated to be about seven per second.
Meanwhile, the average number of transactions in Ethereum is up to 15 per second. Such low rates of processing are attributed mostly to the consensus mechanism, PoW, which is used in the Bitcoin technology.
High processing power and time are required by the nodes to compute the PoW algorithm to add the block into the blockchain network. According to the report in , to process 30 million transactions, 30 billion kWh of electricity was spent, which accounted for about 0.13 percent of global electricity consumption.
In the energy sector, for large scale operations, the number of transactions per second is very high since thousands of users are simultaneously involved in the process of buying and selling energy. This creates a large overhead upon the nodes involved in the consensus and validation process. This problem can be addressed by replacing the PoW consensus algorithm either with the Proof-of-Stake (PoS) or the Proof-of-Authority (PoA) algorithm. These algorithms require much less computing capacity and support much higher rates of transactions. A new blockchain platform named EnergyWeb blockchain is aimed specifically at the energy sector with transaction rates as high as a few thousand per second. It uses the PoA consensus mechanism, which gives it such high processing rates.
Further research and innovations have to be carried out to find solutions to properly scale up the platform to accommodate the requirements of the smart grid system without compromising on the security aspects .
Other so-called “second-layer” solutions are intensely being researched by the community for addressing the scalability issues [32,87]. Off-chain  and side-chain  techniques have been proposed for reducing the number of transactions and for parallelizing the transaction validation, respectively. Research is also leading to advancement in the enabling technologies such as Distributed Hash Table (DHT) , InterPlanetary File System (IPFS) , and nonlinear block organizations such as Directed Acyclic Graph-based chains (DAGchains)  to potentially address the scalability and throughput challenges.
Chances of Centralization
Currently, blockchain application in the energy sector is still a budding technology and is prone to attacks from the energy conglomerates who might exploit it for financial advantages. One of the reasons for centralization is the clustering of mining nodes into mining pools for better computational capacity.
The only chance of changing the transactional data in a block is through the 51 % attack, where the attacker controls 51 % of the computational capacity in the network. By clustering the mining nodes into pools, there exists a risk of the mining pools acquiring enough resources to plot a malicious attack. Another reason for centralization is the fact that much of the architecture in the energy sector is based on consortium or private blockchains.
The reason for their popularity is the problem of power wastage and latency associated with public blockchain architectures. Since a predefined set of nodes are responsible for validation and consensus in the public blockchains, chances of malpractice exist. Therefore, strict supervision under governmental laws should be enforced especially in the beginning stages to ensure security.
Development and Infrastructure Costs
Implementing blockchain in the smart grid requires high infrastructural costs for re-architecting the current grid networks, upgrading smart meters to aid in transactions through smart contracts, infrastructure for Information and Communication Technologies (ICT) specific for Blockchain operations, other related Advanced Metering Interfaces (AMI) and software for development of the whole platform.
Such high infrastructure costs may dissuade grid operators from the incorporation of blockchain into the grid structure. The current infrastructure of the grid has been adopted after years of research and development and it yields optimal results with much less overall expenditure. For example, the grid communication system currently employs technologies such as telemetry which is more mature as well as much less expensive compared to blockchain.
Legal and Regulatory Support
The regulatory bodies do support the active participation of users in the energy market, and the formation of community energy structures. However, when it comes to radical changes in the main power grid framework, the current grid legal system does not support the trading of energy from prosumers to consumers and does not endorse the adoption of the distributed ledger into the framework. New types of contracts have to be developed especially for the P2P trading system and changes in the energy tariffs need to be brought about to support such services.
Such matters are heavily regulated in the current grid system. For these reasons, even though blockchain technology has proven its worth in the formation of microgrids, without amended legal structures, it is very challenging to adopt the technology into the main grid framework.
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