In this video you will learn about a subject that no one likes talking about: the environmental impact of Non-Fungible Tokens, or NFTs.
We take an in-depth look into the carbon footprint of blockchain technology and we break down every Watt-hour of energy consumed in processing NFTs from creation to sale.
We created this video to provide a factual, un-opinionated view based on a recent study, with the idea to spark a well-informed conversation.
Things to know before we start
NFTs briefly defined
NFTs are a way to verify true ownership of a digital item by attaching a unique key to it via a process called minting.
When an NFT is minted, data that represents ownership is stored on a blockchain network and whoever started the minting process is given the key that unlocks the ownership data on the blockchain.
When you buy an NFT, you buy the only verifiable version of the item. This naturally increases its value because the item is unique in comparison to it’s copies that are non-NFT versions.
Power consumption of blockchain technology
NFT data is stored on the blockchain and through the Proof-of-Work mechanism, data blocks are checked by miners in order to reach consensus about the integrity of the data.
This process is what makes blockchain technology highly secure and decentralized, but the continuous data checks costs computational power.
Regular blockchain usage such as trading cryptocurrencies require, simply put, two actions: currency IN registration and currency OUT registration.
In the case of NFTs, multiple blockchain data blocks are added, which in comparison with regular usage requires more checks, simply because all the NFT data is larger in size than regular transaction data.
This calls for the argument that the power usage, and therefore carbon footprint, for just NFTs is out of balance.
Carbon footprint calculation
To clarify first, what exactly is a carbon footprint?
A carbon footprint is the sum of all carbon emissions released throughout a product’s manufacture process and use.
As you can imagine there are many variables, so we usually refer to an approximation when discussing carbon footprint.
In the case of calculating the carbon footprint of NFTs there are several phases in the process that have no known carbon footprint and there are very few scientific peer-reviewed publications on the topic.
Hence, estimating the carbon footprint of creating an NFT is difficult and at this moment relies on estimations.
Let’s look at the process specifically for NFTs that use the Ethereum blockchain. A couple of things must happen to create, or mint, an NFT:
- At the moment of minting, the token must be verified as a commodity on the blockchain
- The account balance of the owner must be adjusted to reflect the addition of that commodity. This enables it to be exchanged or verifiably “owned” in the future.
- The transactions mentioned above must be included in a block on the blockchain.
- All miners must reach consensus that the block is valid via the Proof-of-Work mechanism.
Miners are responsible for all of these tasks and the Proof-of-Work mechanism informs the entire Ethereum network about the actual ownership status of the NFT.
This means that mining must be sufficiently challenging, or else the Proof-Of-Work system is susceptible to faulty data.
Looking at the mining process, a single Ethereum transaction has a carbon impact of 33.4 kilograms of CO2, which is roughly comparable to 74,000 VISA transactions.
In contrast, the average transaction for NFTs has a carbon footprint of roughly 48 kilograms CO2.
Carbon footprint data
80,000 transactions were examined, involving 18,000 NFTs on the SuperRare NFT marketplace, which is one of the more popular NFT marketplaces at this moment.
The average footprint of a single transaction involving an NFT, including minting, bids, sales, and transfers is 82 kilowatt-hour, with outputs of 48 Kilograms Carbon.
This is more than twice the cost of a regular Ethereum blockchain transaction.
Now, a single NFT may include many transactions – including minting, bidding, canceling, sales, and ownership transfers. Dividing the footprint by transaction type, we get:
- Minting: 142 kilowatt-hour, 83 Kilograms Carbon
- Bids: 41 kilowatt-hour, 24 Kilograms Carbon
- Cancel Bid: 12 kilowatt-hour, 7 Kilograms Carbon
- Sale: 87 kilowatt-hour, 51 Kilograms Carbon
- Transfer of ownership: 52 kilowatt-hour, 30 Kilograms Carbon
This often boosts the footprint of a single NFT into the 100-900 kilowatt-hour range, as well as hundreds of Kilograms of Carbon emissions, if not more.
In reality, the average NFT has a footprint of roughly 340 kilowatt-hour or 211 Kilograms Carbon of the 18,000 NFTs on the SuperRare marketplace.
A single NFT footprint is similar to a month’s worth of total electric power use for a European resident, with emissions identical to driving 1000 kilometers or flying for two hours.
It’s also important to remember that each time an NFT is created or sold, it’s a new transaction.
Now imagine this: one single-edition NFT costs an energy usage of 340 kilowatt-hour and emissions of 21 Kilograms of Carbon.
A single artist would very likely sell multiple NFTs, which would multiply those numbers proportionately.
How NFTs are impacting the environment
67% of the 633 artists on SuperRare have NFTs with a CO2 footprint greater than one tonne, even though half of the artists have just joined the platform in the previous six months.
18% of the artists’ NFTs had a carbon footprint larger than 10 tonnes. To put it in context, this is the equivalent of 12 transatlantic trips or a 5-year supply of electricity for an European resident.
On SuperRare, the average footprint of an artist’s NFTs is 10 megawatt-hour, 6 tonne CO2, whereas the median is 3 megawatt-hour, 2 tonne CO2.
That makes the average NFT footprint equivalent to an European resident’s electricity consumption for 3 years, or driving for 30,000 kilometers in a petrol-fed car or taking a flight for 57 hours straight.
Now let’s take all the NFTs registered on SuperRare and see their combined impact on the environment to get an idea of the bigger picture.
The total number of NFTs currently on SuperRare is 18,159. The ecological cost of keeping track of all these amounts to the energy usage of 6,154,717 kilowatt-hour, or roughly 6 Gigawatt-hours, and emissions amounting to 3.8 Metric tonnes of CO2.
This is equivalent to 2000 years worth of electrical energy consumption by a single person in Europe, or driving for 20 million kilometers and flying for 37,000 hours.
Keep in mind that these numbers are only for one of many NFT marketplaces and also based on numbers at the beginning of the NFT revolution.
The fundamental reason for the high energy consumption of blockchains like Ethereum and Bitcoin is that they use a consensus mechanism called Proof-of-Work.
Proof-Of-Work is an excellent system to verify data integrity, but as global adoption of blockchains that use Proof-Of-Work technology increases, so does the power consumption by miners to verify the data.
Other blockchain variants that offer NFT support such as Tezos, Symbol, and Polygon, all make use of the improved Proof-of-Stake mechanism that does not require large amounts of computing power and therefore use less electricity.
Tezos for example claims that their blockchain uses only 0.00006Terrawatt-hour of energy per year, compared to 33.57Terrawatt-hour for Ethereum.
However, there is good news for Ethereum fans.
With ETH2.0, a greener Proof-Of-Stake upgrade is proposed for the current Ethereum ecosystem. Ethereum plans to bring down the costs as well as the ecological impact of not just NFTs but the Ethereum blockchain as a whole – by as much as 99.98%.
Another possibility is the utilization of carbon offsets.
A carbon offset is a payment you make to help fund a project that reduces carbon emissions, such as developing solar power plants to reduce the use of fossil fuels or removing carbon dioxide from the atmosphere, like planting forests.
The number of offsets you buy can theoretically match the number of carbon emissions you produce, so the two can be “canceled out.”
Though they appear to be a good solution, specialists advise that they should only be used when there are no other options because it can take decades to offset the carbon emissions.
Now you know how NFTs impact the environment and you are better equipped with knowledge to make an educated decision whether you support or disapprove of their usage.
Keep in mind that, regardless of whether the blockchain uses Proof-of-Work or Proof-of-Stake, electricity consumption isn’t the only factor that contributes to its carbon and environmental footprint.
More computer hardware is used as the number of bitcoin miners and stakers grows, which has its own industrial and extractive effects. As a result, the total carbon footprint of NFTs is almost sure to be larger than previously projected.
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