The 28 Most Sustainable Cryptocurrencies

UPDATE: Following the immense interest in this topic and great leads on other green cryptocurrencies, I’ve added even more tokens/networks below for our 2023 list. We’ve also written recently about the push for greater sustainability in the NFT community.

Keep the suggestions coming, ideally with solid leads/info on why a token deserves attention from investors who care about sustainability, and I’ll do my best to take a look. Are you a Dogecoin fan? See why everyone’s favorite canine-inspired cryptocurrency didn’t make this list here.

How we compiled this list

Truth be told, it’s incredibly difficult to point to any one currency as being ‘greener’ than others. This is because there are so many parameters at play. Many much smaller cryptocurrencies, for instance, naturally have a far lower energy footprint because they involve far fewer daily transactions compared to Bitcoin. Scale them up, however, and they may be just as bad, if not worse than the cryptocurrency we currently love to hate.

That said, some cryptocurrencies are inherently more energy efficient than Bitcoin. Why? Because Bitcoin relies on a ‘Proof of Work’ system that involves huge amounts of calculations (and, thus, processing power) to produce a single token. Cryptocurrencies that instead use a ‘Proof of Storage’ or ‘Proof of Stake’ system use far less energy, as do currencies using a technology called block lattice, which doesn’t require mining.

Even among ‘Proof of Work’ cryptocurrencies, however, some are more energy intensive than others. This is primarily because these currencies use ASIC-resistant algorithms that consume significantly more energy than should be expected relative to how much of the cryptocurrency market they represent. A good example of this is RavenCoin which, by one calculation, accounts for 4.32% of the total rated power of the top 20 cryptocurrencies but has a market capitalization of just 0.06%. Interestingly, Bitcoin uses an algorithm that does allow for mining ASIC-based devices, and these devices are considerably more energy efficient than conventional graphic processing units (GPUs).

As Bitcoin rises in value, the climate suffers

Market dynamics also play a big role in the energy consumption of cryptocurrencies. In numerous cases, market slides or crashes that drop the price of Bitcoin, Ethereum, or other big players in this area lead to miners slowing down or turning off their devices as it’s no longer profitable to run the machines at that price.

In November 2018, for instance, the Digiconomist estimates that Ethereum’s miners more than halved their energy consumption (from around 20 TWh to 10 TWh) in under 20 days because the price tanked. As the price of Ethereum has once again risen in 2021, so too has the energy consumption associated with the cryptocurrency. As of March 31^st, 2021, Digiconomist estimates Ethereum as using more than 31 TWh annually, an all-time high.

So, which cryptocurrencies have a shot at being more sustainable than Bitcoin? Here are a few of the main contenders, in no particular order, presented with the caveat that this is absolutely not investment advice. At the time of writing, I have no investments in or ties to these or any other cryptocurrencies.

#1. SolarCoin (SLR)

SolarCoin is global, decentralized, and independent of any government. You can spend and trade SolarCoin just like other cryptocurrencies, but the key difference is that the platform aims to incentivize real-world environmental activity: verifiably produced solar energy.

How it works

SolarCoin has a novel approach to cryptocurrency, creating 1 Solarcoin for every Megawatt hour generated from solar technology. Currently, this network mostly relies on users uploading documentation to prove energy generation, but the Internet of Things may one day streamline this process with automatic updates from solar arrays.

Consider SolarCoin as a helpful way to more quickly offset the cost of installing a solar array!

#2. Powerledger (POWR)

POWR was an Ethereum token established in 2016/17 that powers the Powerledger platform. It debuted on Coinbase in November 2021, with the token’s price rising rapidly even while most cryptocurrencies fell in a market-wide crash.

POWR is required to participate in the Powerledger network and helps secure its various products, including energy trading, clean energy tracking, and verification.

As an aside, Powerledger is one of the few blockchains/cryptocurrencies I’ve encountered that has a female co-founder. Doctor Jemma Green is the Executive Chairman and co-founder and leads a team that includes several other women.

How it works

The Powerledger platform facilitates peer-to-peer energy trading and is effectively an operating system that tracks the trading of energy, flexibility services, and environmental commodities. More simply, renewable energy sources like wind and solar are somewhat uncertain, with variable output minute to minute, day to day. A centralized power grid is increasingly problematic when energy inputs and outputs are inconsistent. Powerledger offers a distributed, decentralized network that helps producers track, trace, and trade energy in real-time, making for more stable, resilient energy grids.

As a real-life example, Powerledger partners with the Midwest Renewable Energy Tracking System (M-RETS) to facilitate the trading of Renewable Energy Certificates (RECs) across North America.

In June 2021, POWR switched from the Ethereum platform to being a customized Solana-based blockchain. The rationale behind this move was to take advantage of the Solana code base’s scalability (which just isn’t there for Ethereum yet). Powerledger also integrated Safecoin’s voter subset consensus to reduce the number of administrative type transactions that the blockchain has to handle, keeping the platform secure and energy-efficient.

#3. Cardano (ADA)

Cardano was developed by the co-founder of Ethereum, Charles Hoskinson, and was tested by academics and scientists as the world’s first peer-reviewed blockchain. It functions mainly as a digital currency but can also be used for digital contracts, DApps, and other purposes. Compared to Bitcoin’s 7 transactions a second, Cardano can achieve 1000 per second.

How it works

Cardano is inherently more energy efficient than Bitcoin as it uses a ‘Proof of Stake’ consensus mechanism where those participating in the currency buy tokens to join the network. This helps save a staggering amount of energy, with the founder of Cardano claiming that the cryptocurrency network consumes only 6 GWh of power.

Cardano is similar in some ways to Ethereum, but without a lot of the bloat associated with the latter token. This enables Cardano to scale up to meet increased demands for the cryptocurrency, without compromising on speed or efficiency.

#4. Stellar (XLM)

The Stellar network was released in 2014 (forking off from Ripple) with the goal of bridging the gap between traditional financial institutions and digital currencies. Stellar doesn’t charge institutions or individuals for using the network and is increasingly seen as a serious alternative to PayPal as it enables faster, easier, and more cost-effective cross-asset and cross-border transactions.

Stellar is operated by the Stellar Development Foundation, a non-profit organization. It got its start with funding from Stripe (the payments startup), along with donations from BlackRock, Google, and FastForward. Tax-deductible public donations fund the network’s operating costs and the hard market cap for Lumens and removal of an inflation standard demonstrates that the SDF is looking to maintain a network that enables easy, accessible, low-cost cross-border payments rather than to make a quick buck with massive gains in the price of Lumen.

The network has also attracted serious engagement from IBM and Deloitte, as well as banking institutions in Nigeria, the Philippines, India, France, the South Pacific, and most recently the Ukraine. This brings to life the SDF’s vision to “unlock the world’s economic potential by making money more fluid, markets more open, and people more empowered.” Stellar was the first distributed technology ledger to receive certification as Shariah compliant.

How it works

Through the Stellar network, you can exchange US Dollars, Bitcoin, Pesos, Yen, and pretty much any currency traditional or crypto. The network’s token, Lumens, are used to facilitate these trades on the blockchain-based distributed ledger at a fraction of a cent and with great efficiency (which also translates to a lower carbon footprint). The network also allows individuals and institutions to create tokens for use on the network, which has inspired some to use the network for sustainability initiatives such as investing in renewable energy.

The key distinguishing feature of the Stellar network is its consensus protocol. This SCP is open-source and relies on authentication of transactions occurring through a set of trustworthy nodes rather than running through the whole network as a proof-of-work or even proof-of-stake algorithm. The cycle for authentication is thus much shorter and faster, keeping costs low and energy use to a minimum. The algorithm behind this is known as a federated byzantine agreement and is an energy-efficient alternative to the Bitcoin style traditional mining network.

Stellar’s token, Lumens (XLM), can be bought and sold on most exchanges, including Binance, Coinbase, Kraken, Bittrex, Bitfinex, Upbit and Huobi.

#5. Nano (NANO)

Nano is free, fast, and uses considerably less energy than Bitcoin and many other cryptocurrencies. It has been around since the end of 2015 and has a relatively small carbon footprint even now. It is also scalable and lightweight as it doesn’t rely on mining.

How it works

Nano uses block lattice technology, which is energy efficient. It is still reliant on a Proof of Work mechanism, but the block lattice goes beyond blockchain to create an account-chain for each user on the network. The Nano platform uses a system called Open Representative Voting (ORV), where account holders vote for their chosen representative, who then work to securely confirm blocks of transactions.

On the Nano platform, user accounts can be updated asynchronously, rather than needing to involve an entire linear blockchain as is the case with Bitcoin and others. Instead of competition and delays, then, Nano involves just the sender and receiver account-chains and can handle as many as 125 transactions per second.

#6. IOTA (MIOTA)

As a cryptocurrency, IOTA has not proven as volatile in terms of price as many other tokens. While good news for those looking for more stability in the market and greater financial sustaianability, this has proven disappointing for those investors looking for the same pay-off as with early investments in Bitcoin, Ethereum, or other altcoins.

How it works

In terms of energy sustainability, because IOTA uses Fast Probabilistic Consensus for consensus and only relies on Proof of Work in part, the overall energy consumption of the network is very small. The best figures available for IOTA’s energy consumption come from a PhD student called Amir Abbaszadeh Sori. Writing before the algorithm update, Abbaszadeh Sori calculated the average ECPT (energy consumption per transaction) for IOTA and found that each transaction used just 0.11 Watt hours.

This is very low, even compared to more established financial networks such as VISA and Mastercard. And, like many cryptocurrencies, IOTA blows Bitcoin out of the water in terms of energy use. With the new updates set to make Atomic Transactions the norm for IOTA, this could reduce the transaction size from 1.7kb to less than 100 bytes, presumably reducing the energy consumption accordingly.

Indeed, IOTA released figures in May 2021 outlining a possible 33-95% reduction in energy consumption associated with the Chrysalis upgrade, reducing the energy requirement to just over a millionth of a kWh per transaction.

To calculate the ECPT under the current algorithm though, Abbaszadeh Sori used three smartphones with different processors and versions of Android (but no iPhones) and sent an iota token 25 times with each device. The measure of energy used included approval of the transaction, complete proof of work, preparing inputs and outputs, validating the receive address, synching the account, and final validation.

While the results were very clearly in favor of IOTA as a much more eco-friendly cryptocurrency, Abbaszadeh Sori himself acknowledges some limits to his study. For instance, there’s no accounting for IOTA nodes and IOTA Coordinator energy consumption. And now we have an updated IOTA 1.5, which no longer has the Coordinator Node, these calculations are less relevant.

That said, if we take the above figure for EPCT and multiply it by the 1000-1500 transactions per second that the current IOTA system is said to be able to handle, this amounts to annual energy consumption for IOTA of:

1000-1500 TPS = 31536000000-47304000000 transactions per year

0.11 wH per transaction = 3.47-5.2 Gigawatt hours per year

At the low end, this amounts to around the equivalent of 2,459 metric tons of greenhouse gas emissions annually. That’s 535 passenger vehicles on the road for a year, or the energy used by 296 homes for a year. At the higher end, with 1500 TPS, the numbers rise to 3,687 metric tons of GHG CO2-eq. That’s 802 cars on the road for a year, and 444 houses powered.

#7. EOSIO (EOS) 

EOSIO is a public blockchain beloved by developers because it is simple to set up and write applications in several programming languages, is highly scalable, and costs nothing.

How it works

EOSIO is another ‘Proof of Stake’ platform that uses pre-mined EOS tokens that can be traded on standard cryptocurrency exchanges such as Coinbase, Binance, and Kraken.

#8. TRON (TRX) 

Based in Singapore, TRON is a non-profit organization and public blockchain supporting almost every programming language. The peer-to-peer platform allows creators to share applications directly on the blockchain, making the whole process more energy efficient.

How it works

TRON operates using decentralized governance based on a two-tier model of Super Representatives (SR) and Super Representative Partners, with every account able to become an SR and able to vote for SRs.

The TRON currency, Tronix, is pre-mined and can be traded on Binance and other exchanges, with big plans afoot for TRON’s future, including using it to create decentralized gaming platforms. 

In October 2021, Tron announced its development of a $300 million fund called JustPlay (in partnership with APENFT and WINKLink) to invest in GameFi projects. Tron lends itself to decentralized gaming and this latest project leverages interest in play-to-earn apps on the Tron network.

#9. Signum (SIGNA)

In June 2021, Burstcoin officially changed its name to Signum, under the symbol SIGNA. The original Burstcoin is now essentially void due to a hard fork following a significant price decline after the crypto was delisted from Poloniex in May 2019.

Burstcoin was possibly the first blockchain to use Turing-complete smart contracts which allow for the creation of non-fungible tokens (NFTs) and use in on-chain games. As Signum, it likely remains one of the most environmentally friendly, sustainable cryptocurrencies as it has been using ‘Proof of Capacity’ rather than ‘Proof of Work’ since 2014 and recently updated to ‘Proof of Commitment’, along with the introduction of Smart Tokens.

How it works

With Signum, ‘miners’ are rewarded for using storage space for ‘mining’. Meaning that a computer with a 1 terabyte hard drive barely uses more energy to mine SIGNA than an idling computer. This makes it far more efficient than ASIC mining or GPU mining on a ‘Proof of Work’ algorithm.  It also makes it more equitable as you don’t need high-powered tech to mine SIGNA; you can even mine it using old mobile phones!

In 2021, Signum introduced Proof of Commitment (PoC+) decentralized consensus as the evolution of the Proof of Capacity (PoC) consensus. Miners can easily increase their effective storage capacity by committing a SIGNA balance (stake) in their account. This helps secure the network and improves the miner’s chance of earning mining rewards. PoC+ is arguably more sustainable as it increases effective capacity without the need for more hardware.

In October 2021, Signum introduced Smart Tokens. The idea here is a blockchain where tokens exist outside of smart contracts. These tokens thereby avoid the constraints of smart contracts and don’t need to be imported into your wallet. They are “unique entities that can be transferred or traded directly between accounts”.

The network is driven by volunteers and in 2021 founded Signum- Network Alliance (SNA), a not-for-profit organization to help Signum fulfill its vision of sustainability and innovation in blockchain technology.

You can trade SIGNA on Bittrex, STEX, and other cryptocurrency exchanges.

#10. Holochain/HoloTokens (HOT)

2021 was a big year for Holo. The crypto token price rose to nearly 53 times that of the 2018 ICO price (in USD terms, as of December 2021) and the company gave its Elemental Chat platform a test run, with a public release expected shortly. 

In September 2021, Holo released a “Sharding Ready” version of Holochain, followed by two additional releases to enhance usability by community developers and the Holo team. 

The ICO revolved around a pre-sale of cloud-hosting services as transferable ERC20 tokens called HOT on the Ethereum public blockchain. Again, this makes Holo different to other cryptocurrencies in that it is backed by a tangible asset (cloud-hosting services). Holo charges a fee on transactions using the P2P network, meaning that revenue is tied directly to the number of apps and hosts on the network.

How it works

Holochain is an open-source framework for peer-to-peer applications and its token HoloTokens (HOT) requires no mining. This means that you don’t need any specialized processors, nor is there excessive energy use involved in generating this cryptocurrency. Anyone who hosts hApps on their computer or device can receive HOT in return.

Holochain is immediate and efficient, does not rely on proof-of-work or proof-of-stake, but still enables scalable crypto-accounting. Each user provides a small amount of computing and storage, allowing P2P web applications to function, in theory, at a massive scale without need for centralized data centers or infrastructure. This depends largely on how many users sign up, however.

The cool thing about Holochain is that it can operate through a regular browser, without Holo Hosts needing to install any software. This makes it much more accessible to new, curious, and perhaps hesitant users. Holochain provides a bridge from the decentralized, P2P developer world to existing payment systems.

Because Holochain is a ‘pragmatic compromise,’ as noted by the company itself, some parts of this network are centralized. This makes it rather unique among cryptocurrency projects which typically aim to be entirely decentralized and rely fully on blockchain technology. In essence, Holo acts as a bridge between a fully decentralized network and traditional, familiar internet browsers, helping to expand the ecosystem and marketplace for DApps.

#11. DEVVIO

DEVVIO’s initial community offering was set to occur in June 2021, but there’s still no sign of this happening as of December 2021. Details remain scarce, so while this has the potential to be a good ‘green’ cryptocurrency, I’m increasingly wary that it’s going nowhere, especially as the team doesn’t seem to have many actual developers on staff.

The Devvio platform does appear to have gained some attention for its work in the ESG (Environmental, Social, Governance) space, however. So, while this may not be a crypto that’s going to skyrocket in value if an ICO ever happens, Devvio may be worth looking at for companies that need help with their ESG program.

According to DEVVIO founders, the DEVVIO network uses one millionth of the energy usage of Bitcoin and generates far less in terms of greenhouse gases. It was designed specifically to reduce energy expenditure and be a ‘greener’ cryptocurrency. This is clear from the founders’ commitment to creating DEVVIO as a blockchain ecosystem that can support multiparty collaboration and trust across stakeholders working in the field of environment and sustainability.

The DEVVIO system can be used to authenticate green certifications, enable markets for carbon credits, and facilitate financing for sustainability projects. And it does this without creating inefficiencies and massive energy requirements as projects scale ever upward. This isn’t a proof-of-work blockchain like Bitcoin. Instead, individual nodes talk to each other, creating an energy efficient system. It is also time efficient in that a web developer can quickly hook into DEVVIO’s blockchain.

DEVVIO’s current partners include Avnet and Panduit, which help companies embrace carbon neutrality in part by connecting big corporations to companies generating carbon credits through specific actions such as tree-planting, installing solar power infrastructure, and so forth.

How it works

DEVVIO is a distributed accounting protocol based on sharding, layer 2 protocols, and an efficient consensus mechanism. It can currently execute up to 8 million transactions per second (TPS). Each shard represents a blockchain ledger and thousands of these shards can be added to eventually enable tens of millions of TPS. This is an example of horizontal scaling, meaning that because each shard is independent, every transactions doesn’t have to go through the entire network to be authenticated; it just has to go through one independent blockchain.

To create the necessary complexity for security, DEVVIO has transactions move between shards, but each wallet is only assigned one shard. Payment happens on one shard (as part of Tier 1) and settlement on another (the Tier 2 network).

#12. Hedera Hashgraph (HBAR)

Hedera Hashgraph passed the number of Ethereum (ETH) transactions on May 6^th, 2021, making it one of the world’s biggest cryptocurrency networks. In theory, Hedera Hashgraph could process more than 100,000 TPS, which would allow it to easily rival Visa and other mainstream payment systems. Thankfully, this cryptocurrency (HBAR) is a proof-of-stake token, meaning it uses far less energy than proof-of-work tokens like Bitcoin.

HBAR has a current supply of around 8 billion hbars and a fixed supply of 50 billion hbars. It is a decentralized public network used for in-app payments, micropayments, and transaction fees, as well as for network protection. Developers can use Hedera to build secure applications with near real-time consensus. This is because instead of being a block ‘chain’, Hedera is more of a graph. In fact, it’s based on technology called a Directed Acyclic Graph (DAG) which means that the speed of transaction verifications increases as more transactions are added to the network.

The list of owners and the governing council of Hedera is impressive, including Avery Dennison, Boeing, Deutsche Telekom, DLA Piper, FIS (WorldPay), Google, IBM, LG Electronics, Magalu, Nomura, Swirlds, Tata Communications, University College London (UCL), Wipro, and Zain Group.

Hedera Hashgraph consists of four main services, including HBAR, the cryptocurrency that allows for low-fee, highly customizable transactions. The other services include smart contracts, file service, and consensus service.

How it works

Hedera Hashgraph works through a system called asynchronous byzantine fault tolerance (aBFT). This allows for high-level security even if there are malicious actors on the network. It is faster than Bitcoin or Ethereum because transactions are processed in parallel, rather than having to go through the whole blockchain in a serial manner.

The network reaches consensus through ‘gossip,’ with nodes on the Hashgraph talking to each other and comparing notes on the network’s transactions, instead of mining. Select transactions are deemed ‘famous’ by the nodes because they are communicated early in the gossip process and are then verified by multiple nodes across the network.

Hedera Hashgraph plans for more upgrades to the network in the second half of 2021, including introducing sharding. This will split the network into multiple shards to enable an increase in transactions.

One of the cool things about Hedera Hashgraph is that it is already being used to facilitate sustainability projects. This includes through Power Transition, a software system backed by Hedera Hashgraph. This highly scalable digital energy platform allows people and companies to control energy use from micro grids to national grids. It can help to reduce costs and make the move to a zero-carbon economy by dramatically improving communication between players in networks of any size, making for greater energy efficiency.

Power Transition estimates that the Hedera Hashgraph platform is 250,000 times more energy efficient than Bitcoin, using just 0.001 kilowatt hours per transaction, compared to 250 kWh for Bitcoin (Digiconomist puts it at 950 kWh), 55 kWh for Ethereum, and 0.003 for Visa.

#13. Chia (XCH)

Chia is another interesting cryptocurrency in that it can be mined on Amazon Web Services cloud computing platform. Setting this up takes just a few minutes, with chia ‘farming’ simple and straightforward compared to ‘mining’ of many other currencies.

Unlike many cryptocurrencies, Chia was created by a familiar name: Bram Cohen, the founder of BitTorrent. When the platform was launched, it reportedly led to a shortage of hard drives in China as people scrambled to acquire more storage space on which to farm XCH.

How it works

The Chia Network is a blockchain and smart transaction platform that allows users to take advantage of available hard drive space to run the decentralized network. Instead of proof-of-work, the Chia Network relies on proof-of-space-time. So, storing a certain amount of data over a certain amount of time can earn you XCH, Chia’s token. XCH was created in 2017 in response to the excessive energy use involved in mining crypto.

Chia farming was designed to be accessible, with no specialized equipment needed, nor massive amounts of power. The network’s blockchain transaction platform is called Mainnet and can be downloaded at chia.net. After downloading the software, you can choose to dedicate a portion of your uncommitted hard drive space to the network and this will then tick along nicely while your computer is running, without significantly affecting your machine’s performance or requiring vastly more energy.

#14. Algorand (ALGO)

Algorand is a proof-of-stake blockchain that gets its value because it supports smart contracts. The influence of each user on the network is proportional to their stake in the system, and Algorand’s blockchain is scalable and secure, as well as free from forks and other potential governance issues.

Released in late 2019, Algorand is also relatively new to the crypto scene but was able to manage almost one million transactions per day by December 2020. One of the founders of Algorand, Silvio Micali, is a profession of computer science at the Massachusetts Institute of Technology and a recipient of the Turing Award in 2012, in part for his contributions to cryptocurrencies and blockchain protocols, all of which inspires quite a bit of confidence when compared to other newer crytpos.

The speed of transactions on the Algorand platform and its low transaction fees, in addition to being a permissionless pure proof-of-stake blockchain protocol, all mean that the network is more accessible, scalable, and uses far less energy than Bitcoin and its ilk.

How it works

The pure proof-of-stake approach of Algorand means that all validating nodes are known to each other and have to agree to create a new block each time.

Algorand does not involve mining, and the network is trying to lead the way in blockchain sustainability by creating a carbon-negative network. It was designed to be energy efficient from the get-go and has committed to offsetting any emission gaps to reduce its environmental impact further. Micali himself has said, “I care about the planet” and that the proof-of-stake algorithm “drives electricity consumption to almost zero.”

On April 22, 2021, Algorand announced that its blockchain is fully carbon neutral, thanks in part to its partnership with ClimateTrade. This organization is a leader in carbon emissions transparency and traceability and the partnership with Algorand allows CimateTrade to enhance its sustainability efforts with corporations worldwide.

The Algorand Foundation is a not-for-profit organization behind this development. The Foundation also envisions bringing on board a whole community of blockchain and mainstream developers including those wanting to use the platform to support sustainable endeavors.

Algorand and ClimateTrade plan to implement a system whereby Algorand’s carbon footprint on-chain for a specific number of blocks will be notarized, allowing the equivalent amount of carbon credit to be calculated. This Algorand Standard Asset (ASA) will then be locked into a green treasury and the protocol will continue running as carbon-negative by carefully tracing and offsetting these amounts.

The Algorand blockchain currently has 10 billion ALGO, with distribution continuing to roll out up until 2030. ALGO is currently able to be bought and sold on Coinbase, Binance, OKEx, Kraken, and Huobi.

#15. MetaHash (MHC)

MetaHash offers a fast, efficient decentralized network with zero fees and the ability to mine/forge MHC using fairly low-key hardware. MHC is just one of four parts of the MetaHash project, the others being TraceChain, MetaApps, and MetaGate. TraceChain is an algorithm for routing traffic over the network. MetaApps allows users to write stand-alone decentralized applications using C++, PHP, and Solidity, among other programming languages. MetaGate is an open source user interface for third-party developers.

How it works

Metahash is another proof-of-stake protocol that is far more efficient than its pure proof-of-work counterparts. It originally operated using a delegated PoS mechanism but has transitioned to a multiple PoS mechanism to address issues that compromised decentralization of the network. In this system, “multi-layered validation provides the basis for protecting a network against corruption. In cases when the central
network entities, which generate blocks, appear to be corrupted, the rest of the network may vote to rebuild the network and to re-distribute the roles, thus, neutralizing the threat.” This model also allows validation and block distribution to run in parallel, decreasing consensus time and improving efficiency.

#16. Harmony (ONE)

Harmony is an Ethereum based, cross-chain application platform with a cryptocurrency (ONE) launched in June 2019. Harmony primarily creates a bridge between creators and consumers of non-fungible tokens (NFTs). Its main benefits are using an energy efficient proof-of-stake algorithm, very fast transaction times (with contracts finalized every two seconds), and impressive scaling capabilities.

In September 2021, Harmony announced a $300 million ecosystem development fund intended to encourage more crypto founders, builders and creatives to develop the Harmony ecosystem of apps and NFTs.

How it works

The Harmony platform uses sharding and FBFT consensus algorithms to increase speed and security and reduce the amount of energy required per transaction. This makes Harmony a fairly green cryptocurrency and blockchain.

Harmony works across Bitcoin, Ethereum, Polkadot, and the Binance Smart Chain and is focused on improving scalability across these networks.

#17. Tezos (XTZ)

Launched in 2018, Tezos was one of the original Proof of Stake (PoS) smart contract layer one blockchains. It was also one of the largest initial coin offerings every held, worth $232 million at the time (July 2017). Most (80%) of this initial supply went to investors, with 10% each going to the Tezos Foundation and Dynamic Ledger Solutions. The launch of the Tezos mainnet was delayed by a series of lawsuits from unhappy investors who argued that tez was, in essence, an unregistered security.

Tezos is an energy efficient Proof of Stake (PoS) blockchain that is self-upgradable, scalable, and secure. It is an impressive piece of crypto tech, with a reputation for transparency and innovation. The Tezos blockchain operates using the cryptocurrency tez (not capitalized) and has the ticker symbol XTZ.

Tezos was developed by Arthur Breitman, who published a white paper in 2014 proposing the blockchain. It took four years to launch the mainnet, with the intention from the outset being to create a network that actively invited contributions from the developer community. 

How it works

Unlike Bitcoin, Ethereum, and many other blockchains, Tezos has an on-chain governance mechanism that allows the network to continuously improve without the need for a hard fork. This system means participants in the network can propose, vote upon, adopt, and deploy improvements efficiently. 

The result is a leading edge blockchain network that can quickly innovate. The algorithm enables transactions to be processed quickly, cheaply, and at a fraction of the energy used by Proof of Work networks like Bitcoin. 

Tezos is a collaborative network that operates without an official core team, or employees. It is an open-source software project, and anyone can contribute code to make the blockchain better. The decentralized project has various entities worldwide helping to support the platform’s growth. 

The self-amendment capacity of Tezos avoids the issues with forking that have hounded other blockchains, such as Ethereum. Instead of needing to fork or split into two different blockchains when carrying out major upgrades, Tezos can amend itself without disruption to the network and without creating massive division in the community. 

Another advantage to self-amendment is that the process of upgrading is more easily coordinated and executed at a lower cost. Further amendments are also easier to implement as there remains just one blockchain, not two or more that also require upgrades. 

Anyone who stakes 8,000 tez is known as a Baker and can vote on proposed amendments and upgrades put forward by Tezos developers. The four-step procedure takes around 23 days, and proposals that receive majority support are then tested on a testnet for 48 hours. Those that gain support from a super majority are then fully implemented on the mainnet. Because of the minimum investment of 8,000 tez, there’s a financial incentive to contribute to the success of the network.

Using programming languages 0Caml and Michelson, which facilitate formal verification, Tezos is a super secure blockchain that can be used safely in the aerospace, nuclear, and semiconductor industries. All of this makes Tezos very attractive to a variety of users.

Who uses the Tezos platform?

Tezos allows users to build powerful decentralized finance (DeFi) apps, other tools, games, and NFTs on its network. Current users include Red Bull Racing Honda and McLaren Racing, as well as OneOf, an eco-friendly music-focused NFT platform with artists such as Doja Cat, Quincy Jones, and John Legend.

The French banking giant Societe Generale also signed on to use Tezos for a central bank digital currency.

You can buy tez on most major coin exchanges, including Binance and Coinbase.

#18. Flow (FLOW) 

Flow is both a PoS blockchain that is fast, decentralized, and highly usable and the cryptocurrency native to the Flow network. It is designed for building games, apps, NFTs and other internet-scale protocols and applications that need low-latency (i.e., very fast processing times) and high-throughput (i.e., a lot of transaction happening very rapidly across millions of users).

Flow is a developer’s dream as the platform offers a ton of white papers that provide a complete specification of the system.

How it works

Flow is the brainchild of the team behind CryptoKitties and offers the unique approach of separating mining or validating roles into four distinct processes. This makes things both more efficient and more accessible: anyone with a reliable internet connection can participate as a Flow validator, thanks to a new encoding technique called Specialized Proofs of Confidential Knowledge (SPoCKs) which addresses the Verifier’s Dilemma.

In most blockchains, a single miner or validator performs all or most of the tasks of validation. This slows things down and means some of the work is carried out by multiple parties unnecessarily. With Flow, the pipelined architecture reduces this redundancy and improves efficiency and security by separating out the tasks. Even those with a small amount of computer power available can participate by performing some of the less energy intensive parts of a transaction.

The four validation roles comprise Collection, Execution, Verification, and Consensus, with no sharding needed. On Flow, smart contracts and user accounts can interact in one atomic, consistent, isolated, and durable (ACID) transaction, meaning things flow efficiently and developers can build seamlessly on each other’s code. With Flow, every application on the network can also function as a platform on which to build.

#19. Avalanche (AVAX)

Avalanche is a smart contract platform that uses a PoS algorithm and the native token AVAX, which is deliberately restricted to 720 million AVAX coins in circulation. It has an architecture that allows for custom private or public blockchains to be deployed as subnets, and these subnets can facilitate around 4,500 transactions per second, at a lower cost than networks such as Ethereum. 

Avalanche is compatible with Ethereum’s programming language (Solidity) and is scalable and decentralized, secure and energy efficient. For these reasons, it is popular with developers building DeFi projects, NFTs, games, and more. The Avalanche network consists of three component blockchains: the Platform Chain (P-Chain) which coordinates validators and the creation of subnets; the C-Chain for smart contract creation; and the X-Chain for managing and exchanging assets.

Participants in Avalanche stake AVAX on the P-Chain to become general network validators. A stake can also be delegated to another validator, allowing them to earn a portion of the validator reward. It is also possible to specify validation of a particular subnet blockchain.

#20. Gridcoin (GRC)

Gridcoin is an efficient decentralized blockchain that uses idle computational power to carry out scientific research through the Berkeley Open Infrastructure for Network Computing (BOINC). The platform was launched in 2013 and uses a Proof-of-Stake algorithm. Participants in the network are rewarded with coins using a Proof of Research algorithm through BOINC.

The open source platform uses the native coin GRC and current projects include protein folding through Rosetta@Home, mapping the Milky Way galaxy (Milkyway@home), and figuring out solutions to public health and clean energy problems (World Community Grid). Unlike other scientific cryptocurrencies, Gridcoin can support a wide variety of different projects, limited only by what users of BOINC broadcast.

How it works

As a decentralized network, Gridcoin performs transactions peer-to-peer cryptographically, meaning there’s no need for a central authority to disburse rewards. The original Gridcoin (Classic) used a hybrid PoW algorithm, allowing participants to hash half the time and donate half time to science. The Gridcoin-Research algorithm made the PoW component obsolete as this PoS algorithm allows nearly all the computational power go to science while a tiny amount maintains and secures the blockchain.

Researchers can create their own projects on BOINC for free, and Gridcoin rewards people for granting access to unused computer power otherwise unavailable to these researchers. BOINC has been running since 2003 and is a well-regarded and secure system.

#21. Mina Protocol (MINA)

Mina is touted as the world’s lightest blockchain at just 22 kb. It is powered by participants, who quickly synchronize and verify the network. This makes it arguably more sustainable and egalitarian than many other blockchains which require intermediaries with heavy computational power to run nodes.

Mina Protocol was founded in 2017 by Evan Shapiro and Izaak Meckler but took four years to build and test before its launch in March 2021. In April 2021, the Mina Foundation held a community token sale that raised $18.75 million for the project. This money will be used to maintain the network’s assets and distributed by the foundation as grants for community developers.

The MINA token powers the network, with users rewarded for creating blocks and validating transactions. The initial coin offering was one billion MINA tokens, with more added over time and inflation managed through Mina Protocol governance.

How it works

Mina is decentralized and so lightweight that it allows every participant to act as a full node in the PoS consensus. Transactions are computed off-chain and verified on-chain, using a much smaller proof than most other blockchains. The small proof represents the state of the whole chain, rather than the latest block. 

Because Mina is built on a consistent-sized cryptographic proof, the blockchain remains accessible even as it scales to process billions of transactions. In contrast, the Ethereum blockchain went from just over 5 GB in 2016 to 220 GB in 2021, meaning that the network requires validator nodes to have a huge amount of memory and processing power. 

To send and receive transactions on Mina, every participant has to run a node. The algorithm also requires block producers and snark workers to run effectively. Snark workers help compress network data and generate proofs of transactions. Block producers then bid on these proofs and select the transaction to include in the next block (a bit like conventional validators or miners). 

MINA helps to secure the network and can be used to interact with ‘Snapps”, or decentralized zk-SNARK powered applications built on the Mina Protocol. Invented by MIT professor and Algorand founder Silvio Micali, zk-SNARKs stands for “zero-knowledge succinct non-interactive arguments of knowledge. These apps validate and share proofs of data without sharing the data itself – an attractive system for decentralized finance. 

One of the first Snapps, Teller, is a handy app that helps users keep their information private while proving their credit score to traditional financial services in order to access loans. Such apps are also easily scalable while remaining efficient and cost-effective.

#22. ReddCoin (REDD)

ReddCoin is a standout alt coin designed for use on social media as a digital social currency for tipping or rewarding individuals, charities, or other organizations without requiring an intermediary. ReddCoin uses a PoS velocity (PoSV) algorithm, and the full amount of every tip goes to the recipient, unlike with platforms such as Patreon, GoFundMe, JustGiving and others where the intermediary takes a cut to fund the system.

ReddCoin has itself received donations and is now self-funded and volunteer-run. Established in 2014, ReddCoin is a longstanding cryptocurrency that has seen many improvements, including to its PoS algorithm. There are more than 60,000 users of Redd in more than 50 countries, owing to its ease of use across major social media platforms such as Facebook, Twitter, Reddit, and Instagram.

How it works

ReddCoin uses a Proof-of-Stake Velocity (PoSV) algorithm to validate blocks. This process is called ‘minting’ instead of ‘mining’ on ReddCoin and uses both ownership and activity to delineate value. This algorithm requires much less computing power compared to mining and enables fairly fast transactions (just 60 seconds on average) at low or no cost.

Because ReddCoin’s algorithm is streamlined, transactions can be done on cellphones and other small devices. In fact, everyone who holds ReddCoin is automatically a minter, with a higher stake meaning a greater chance of finding blocks and being rewarded with more ReddCoin.

ReddCoin scales easily and can trade higher volumes as demand increases. And the simplicity of ReddCoin means that even those who don’t understand cryptocurrencies’ underlying technology can still use it easily. Indeed, ReddCoin is about to launch the ReddMobile app which will make social tipping even more straightforward. The app will allow users to tip others with ease and to store, send, and receive ReddCoin on their phones. Existing ReddWallets and ReddIDs can be imported to the new app and the wallet is used to stake ReddCoin with up to 25% annual returns possible.

#23. GoChain (GO)

GoChain was founded in 2017 by a team with experience in cloud computing. The idea was to build a network that was scalable without being energy intensive. It processes transaction in 3-5 seconds, can handle 1300 transactions per second, and has an average fee of $0.01 at the time of writing. GO is the native token on the network and is required for every transaction sent to the GoChain.

The initial coin offering occurred in 2018 and raised a hard cap of around $13.7 million. GO is an Ethereum based ERC-20 token and can be used to access all GoChain services. There are currently nearly 500 million tokens in circulation and plans for another billion to be added gradually. 

How it works

GoChain is a smart contract platform and can be used for transferring tokens and storing files. It is compatible with Ethereum but has a fraction of the carbon footprint, so developers wanting to cut their environmental impact could easily switch chains without requiring code rewrites.

GoChain uses a Proof-of-Reputation consensus mechanism. This is similar to a Proof-of-Authority model, which GoChain still uses for nodes with a very high reputation. The difference is that the GoChain algorithm accounts for all participants’ reputations in ensuring a secure network. To engage in the blockchain, a user has to have a reputation, meaning that anyone trying to cheat the system is quickly prevented from further activity.

#24. EFFORCE (WOZX) 

EFFORCE is the brainchild of Apple founder Steve Wozniak (hence the ticker symbol). The entire purpose of this unique blockchain is to help crypto investors make money while contributing to environmentally sound energy efficiency initiatives.

Typically, the energy efficiency industry is a complex multiparty financial system that is hard to navigate, especially for the average investor. EFFORCE makes investing in energy efficiency projects simple and accessible, which has the potential to dramatically increase overall investment in the sector and a more sustainable future.

Wozniak first dreamt up EFFORCE in 2017, along with co-founders with experience in energy efficiency projects. A presale and roadshow took place in 2019 and the platform development was finalized in 2020 for factories and real estate projects and then listed on HBTC. In the first quarter of 2021, EFFORCE completed its first efficiency project and began Energy Efficiency Sharing. 

The WOZX token was listed for trade on BitEx in April 2021 at the same time that the software platform was opened to the public. A capped number – 100 million – of WOZX were created at launch, with 45% of the tokens allocated privately, including 20% to EFFORCE itself, 20% towards mining incentives, and 15% for ecosystem and consulting activities.

Mining occurs once a successful project launches on EFFORCE. Any token rewards are then issued on a sliding scale over a ten-year period. This helps to protect liquidity of the asset and the value of the token over time.

How it works

EFFORCE allows you (or your company) to offset your future energy bills by investing in energy efficiency projects now. The EFFORCE algorithm then uses smart contracts (called Energy Performance Contracts, or EPCs) to redistribute resulting savings to token holders and initial investors. The redistribution of these rewards is based on exact energy consumption and savings data without the need for any intermediary to assess or estimate savings.

The beauty of EFFORCE is that it commodifies energy savings by creating a new tradable asset class, which has the effect of helping to scale up energy efficiency investments for the benefit of all of us. Energy efficiency has, according to EFFORCE, twice the potential of renewable energy investments in this early phase.

EFFORCE also makes investing in energy efficiency projects more democratic and financially accessible. Where the sector has typically been limited to major investors and large contributions from just a handful of parties, EFFORCE allows anyone to invest at any amount. EFFORCE also solves the problem of putting contributors and savers in contact. 

The platform also acts in a consultancy role, guiding projects through development and funding. At least 1% of total energy savings from all of the projects will be distributed to all EFFORCE token holders. This may be adjusted through the platform’s governance mechanism, with token holders having voting rights.

#25. GreenTrust (GNT)

GreenTrust is a sustainable decentralized blockchain with a carbon neutral network and the aim to help the world become carbon neutral by 2050. 

The network runs on the GNT token which can be exchanged for carbon offset certificates. The general idea is to use the blockchain to better measure, reduce, and offset everybody’s carbon footprint. For every 350 transactions on the network, GreenTrust plants a tree.

How it works

GreenTrust is powered by Binance Smart Chain and uses a consensus mechanism Proof-of-Stake Authority (PoSA) which is energy efficient, fast, and low-cost. The network’s smart contract was audited in June 2021 by Techrate and the GreenTrust project is building partnerships with likeminded organizations also aiming to decarbonize the global economy.

GreenTrust’s transaction fees help fund tree planting and will be used to develop renewable energy projects. There is a total supply of 126 trillion GreenTrust tokens, of which just under 25% are currently in circulation.

GNT is available on Binance, PancakeSwap, and ApeSwap, as well as several other exchanges.

#26. Near Protocol (NEAR) 

Near Protocol is a certified carbon neutral blockchain that hosts various apps, NFTs, games, and more. It even includes an app that helps facilitate the buying and selling of used cellphones. The Near Protocol development platform uses the NEAR token and is also a foundation and collective that gives out grants to develop the Near ecosystem.

The network is energy efficient and low cost, with users and developers earning 30% of transaction fees. And by using the network, users are already offsetting CO2, whether they intend to or not!

NEAR also plans to release an NFT platform called Mintbase, on which crypto artists will create digital artworks that represent South Pole projects. These NFTs will be auctioned off and a majority of proceeds will go towards CO2 offsetting projects in developing countries that are results-based and verified by a third party.

How it works

Near Protocol is a development platform that runs a sharded, PoS, layer one smart contract. The network works with programming languages Rust and AssemblyScript.

Holders of NEAR can participate in network governance and earn tokens for staking or securing the network. NEAR can also be earned by winning a NEAR hackathon, being active in the community, engaging in development bounties, and other activities that help grow the ecosystem. You can also receive NEAR from friends even if you don’t have a NEAR account. This is done through the NEAR Drop, whereby one person can pre-fund a new account and then send a hot link to the account for someone else to retrieve the tokens.

Near was certified carbon neutral in February 2021 by South Pole, a leading low-carbon project developer, and climate solutions provider. This was due to NEAR offsetting its first year’s emissions through documented, verifiable, tree planting and reducing subsequent emissions. The foundation uses a measurement method that includes direct and indirect emissions associated with the network. This includes electricity used to power the network, purchased hardware and cloud services, and even emissions associated with travel and teleworking by the NEAR team.

#27. MobileCoin (MOB)

If you like Signal, you’ll probably already know MobileCoin. This super simple payment method was adopted by Signal as an energy efficient near-zero energy cryptocurrency that runs on the back of existing mobile phone networks. It is easy to use, carbon negative, private and secure, and offers near instantaneous digital cash payments.

To achieve carbon negative status, fans of MobileCoin donated renewable energy to offset the entire network’s emissions for the foreseeable future.

The founder of Signal was an early technical advisor for MobileCoin and the blockchain has attracted a range of key investors including Coinbase Ventures. It raised $66 million in Series B funding and around $107 million in total funding after four years in development. 

MobileCoin is also a supporter of the arts and culture, with a platform called MobileCoin Radio offering space for creators to showcase their work. This is for audio, digital, spoken word, and other work, and there’s even an Artist in Residence program courtesy of MobileCoin. 

How it works

MobileCoin was designed to be used by anyone with a cellphone. Breaking down barriers to engaging with cryptocurrencies, the network engages directly with messaging apps on your phone or desktop computer. It is encrypted, secure, and private, and the blockchain runs on a federated byzantine agreement (FBA) algorithm. This makes MobileCoin energy efficient and fast while remaining decentralized. 

The platform has a number of open source libraries including MobileCoin Fog and MobileCoin is available on hundreds of millions of devices worldwide. It is a leading cryptocurrency payment network, if not the most popular digital cash application. MobileCoin has also secured partnerships with US banks to allow in-app purchasing and direct-to-bank account conversions.

MobileCoin is available on FTX, BitFinex, buymobilecoin.com, and other platforms.

#28. Electroneum (ETN)

Similar to MobileCoin, Electroneum is a cellphone based crypto payment platform launched in 2017. It is based in the UK but has the intention of providing a safe, fast, and secure payment system for the billion or so people with no traditional banking services worldwide. 

Electroneum had an initial coin offering of $40 million and launched its wallet manager in December 2017. Around half of the total supply of Electroneum tokens are now in circulation, amounting to more than 10 billion ETN coins.

In March 2018, the platform launched one of, if not the first Android mobile mining application. The founder of Electroneum, Richard Ells, also founded and launched AnyTask in 2019. This freelancing platform focuses on giving freelancers in developing countries access to the digital economy. Sellers on the platform pay no fees and don’t need a bank account.

How it works

Electroneum was originally built using the Monero codebase but migrated in 2019 to a Proof-of-Responsibility (PoR) blockchain. Unlike the original permissionless network, which allowed anyone to mine ETN for profit, the move to PoR allows for miners to be hand-picked by the project. This permissioned network has 12 validators, all of which are non-governmental organizations (NGOs). These entities earn rewards for validation and use these to fund charitable work. In the future, universities will also be able to act as validators on the network.

The Electroneum network was one of the first to adopt AML/KYC measures to safeguard transactions. As a moderated blockchain using PoR, the network is insusceptible to a 51% attack, with a mechanism to prevent any group of miners from owning more than 50% of the network. If or when an attack does happen, the rogue validator can be shut down quickly and efficiently. 

By offering an on-phone mining app, Electroneum democratizes mining, removing the need for expensive, power-hungry servers. Miners are expected to spend block rewards earned through Electroneum’s PoR algorithm to support humanitarian projects, though this isn’t measured or verified in any way. The algorithm is energy efficient, using an estimate less than half a kilobyte per hash.

Electroneum allows for cross border transfers, with the ability to send ETN anywhere in the world at almost no cost.

Special mention – Ethereum (ETH)

Ethereum has been making a big song and dance about going green for many years, but there’s been little follow through on all that promise. The cryptocurrency still uses enough energy every year to power a major country and as much electricity per transaction as could power an average U.S. household for a day. Still, Ethereum is more energy efficient than Bitcoin and they’re at least trying to make things better.

The founder of Ethereum has long admitted the wastefulness of the bloated cryptocurrency and in 2014 began a lofty project to overhaul Ethereum’s code with the help of the open-source movement. The plan is to replace the current Proof of Work model with a Proof of Stake mechanism, but progress has been slow. As of 2019, the developers scrapped their original strategy of rebuilding the plane while it is in the air and instead adopted a two-chain approach where Proof of Work and Proof of Stake temporarily run alongside each other. They dubbed this Ethereum 2.0.

In December 2020, Ethereum launched Beacon Chain as the first step in this shift of the network. Under Beacon Chain, Ethereum 2.0 stores and manages the registry of validators and deploys the Proof of Stake consensus mechanism. It is currently running alongside the original chain, however, with full implementation not planned until 2022. This means that the touted one hundredfold reduction in energy per transaction is yet to be realized.

(Not so) Final thoughts

With more than 4,500 tokens out there, I’m sure I’ve missed a few excellent options for sustainable cryptocurrencies. Given the exponential growth in this area of digital finance, chances are the best is yet to come anyway. If you know of an eco-friendly cryptocurrency, please leave a comment or send us an email and we’ll take a look. Feel free to check out our environmental analysis of the Dogecoin as well.

In the meantime, if you’re an investor who has already reapportioned your assets from fossil fuel companies and so forth into more sustainable investments, consider doing the same with any cryptocurrencies you hold. And if you already have a solar array set up, or are living a sustainable lifestyle, there’s basically nothing to lose by signing up to SolarCoin and/or BitGreen.