The Unreasonable Ecological Cost of #CryptoArt (Part 2)


  • 27.04.2021 Kyle McDonald has been doing more research on “Per-Transaction footprint responsibility models. The model that I use is what he calls “model_gas”. In his analysis he looks at eight different models, which range from 1/2 of what I calculate in this article, up to 4x to 8x higher. His report is worth a read for those wanting to get into more detail.

Additional notes

These figures are calculated from blockchain data and existing research. Are they “accurate”? They are as accurate as they can be based on the current data and research, which does have many unknowns. Furthermore, the true figures are continually changing. In that respect these figures are best thought of as representing the true scale (e.g. hundreds of Kg C02, tonnes of CO2, tens of tonnes of CO2 etc. i.e. orders of magnitude). The accuracy also depends on the acceptable error margin. One of the most authoritative critiques of the method used by [1] comes from Jonathan Koomey [16], who finds the model too “simplistic”. For an analyst who works with clients where lives are literally at stake if errors are made [19], this is completely understandable. For the purposes of our discussion however, even if the true carbon footprint of a multi-edition NFT is 50 tonnes CO2 instead of 100 tonnes, it really should not affect this conversation — as it is not going to be in reality, 50 grams, or even 50 Kg. Furthermore, the “Bevand” method — which is recommended by Koomey — is used by [15] to estimate the energy consumption of Bitcoin, and is currently producing 40% higher estimates than the method used by [1, 23], rendering it unlikely that the Ethereum estimates will be significantly (e.g. an order of magnitude) over-estimating.

China’s mining distribution (for BTC) in Sep 2020. Note Sichuan (Hydro) is leading. [14]
China’s mining distribution (for BTC) in Apr 2020. Note Xinjiang (Coal) is leading. [14]


So far I’ve chosen to focus most of my analysis (and the website on SuperRarewhich is just one of many CryptoArt NFT platforms, and by no means the worst offender when it comes to carbon footprint. E.g. SuperRare offers ‘one-off’ NFTs. In Part 1, I also share some figures from NiftyGateway (which I calculate in the same way, measuring Ethereum Gas). NiftyGateway doesn’t track bids and sales on-chain. However, they do allow editions of 100s, which incur footprints orders of magnitude higher than those mentioned below.

  • 79977 transactions relating to these NFTs
  • 633 CryptoArtists

Background: how is the footprint calculated?

Different Ethereum transactions require different amounts of Ethereum Gas (not to be confused by ‘real world gas’), based on the complexity of the actions carried out by the smart-contract as a result of the transaction [17]. Blocks also have a Gas limit (currently 12.5 million). This limits the amount of computation that can be required by all of the transactions in a block, effectively also limiting the number of transactions in a block. “In general, the more complex the transactions are, the fewer you can fit within one block” [18]. Thus the amount of Gas required by a transaction is representative of how much of a block it it is taking up. E.g. a simple transaction (~21K Gas) will take up 21000/~12500000 => ~0.17% of a block. Whereas an operation such as ‘minting’ an NFT (~260K Gas) will take up 260000/~12500000 => ~2% of a block. Since the energy required and footprint of mining a block is independent of its contents and number of transactions, the Gas required by a transaction is representative of the portion of a block’s footprint it will incur.

Footprint per unit of Gas

From the total amount of Ethereum Gas and energy consumed by the Ethereum network over a period [1, 2, 3], we can calculate the energy footprint per unit of Gas. Then we can calculate the footprint of a particular transaction³, from the amount of Gas that it used. Likewise for each NFT, by adding up the footprints of each transaction. Carbon footprint is calculated in a similar manner, looking at emissions averaged across regions where mining is most common [7]¹.

Footprint per transaction type

The footprint of a single average ETH transaction is estimated to be 35 kWh [1]. However, this is not the energy consumption of a typical transaction relating to a NFT.

Calculating footprint of NFTs

For each NFT, I search the Ethereum blockchain for all of the transactions that the NFT has been involved in. Using the footprints per unit of Gas that I mentioned above, I can calculate the footprints relating to the NFT (or artist)³.

Footprint per average NFT

79,977 transactions on SuperRare used 12,040,321,070 Gas, giving a total of 6,567,686 kWh (6.5 GWh) and 3,831,601 KgCO2 (3831 tonnes CO2).

Footprint per average transaction relating to a NFT

12,040,321,070 Gas across 79,977 transactions gives:
150,547 Gas => 82 kWh / 48 KgCO2 per transaction (on SuperRare).

NFT Statistics

The data for this section can be found here, and more up-to-date data can be downloaded from

Energy consumption per NFT

Carbon emissions per NFT

NFT Age (time since being minted)

SuperRare’s first NFT was minted 33 months ago.
50% of NFTs were minted in the last 9 months
20% of NFTs were minted in the last 3 months
6% of NFTs were minted in the last month.

Number of transactions per NFT

1 in 9 NFTs (11%) have no transactions in addition to being minted
half (48%) have 3 or fewer transactions
3 in 4 (73%) have 5 or fewer transactions
1 in 14 (7%) have 10 or more
0.5% have 20 or more
0.1% have 30 or more
1 NFT has more than 50 transactions

Artist Statistics

The data for this section can be found here, and more up-to-date data can be downloaded from

Number of NFTs minted per artist

1 in 17 artists (6%) have minted only 1 NFT
1 in 3 (31%) have 5 or fewer NFTs
half (55%) have 10 or more
1 in 3 (36%) have 20 or more
1 in 6 (16%) have 50 or more
1 in 14 (7%) have 100 or more
1% have 200 or more
2 artists have 300 or more NFTs

Energy consumption per artist

Carbon emissions per artist

Carbon emissions per artist

Artist Age (time since joining platform)

1 artist joined over 2.5 years ago
1 in 7 (14%) joined over 2 years ago
2 in 3 (65%) joined in the last year
half (45%) joined in the last 6 months
1 in 4 (27%) joined in the last 3 months
1 in 11 (9%) artists joined in the last month

Income and revenue distributions

NFT primary sales

The average sale price is 0.868 ETH ($975)
1 in 3 NFTs (37%) have not sold at all
Half of the NFTs sold for less than $225 (i.e. median)
4 out of 5 NFTs (78%) sold for less than $1000
1.5% sold for more than $10K
1 NFT sold for more than $100K

NFT secondary sales (10% goes to the artist)

90% have not resold (i.e. zero secondary sales royalties)
99% generated less than $5K (less than $500 for the artist)
3 NFTs (0.02%) generated more than $100K (more than $10K for the artist)

Total revenue per NFT (including primary and 10% secondary sales)

Artist primary sales

The average primary sales income is 24 ETH ($30K)
1 in 7 artists (14%) have made no primary sales at all
Half of the artists made less than $9.5K (i.e. median)
1% made more than $250K
1 artist made more than $1M

Artist secondary sales (10% goes to the artist)

Half of the artists (56%) did not receive any secondary sales royalties.
1 in 3 (38%) generated less than $1K (i.e. less than $100 per artist).
3 artists (0.5%) generated more than $250K (i.e. more than $25K per artist)

Total income per artist (including primary and 10% secondary sales)

The top 0.1% of artists earned 8% of total income ($1.5M of $19M)
The top 1% earned 21% of total income ($4M of $19M)
The top 10% earned 57% of total income ($11M of $19M)
The top 20% earned 75% of total income ($14.5M of $19M)
The bottom 40% earned 2% of total income ($390K of 19M)
The bottom 20% earned 0.2% of total income ($40K of 19M)

Final thoughts

See Part 1 for conclusions, I won’t repeat them here.


  1. The KgCO2 calculation has a larger margin of error compared to kWh. First, it inherits the error of kWh. Second, naturally some modes of energy production (e.g. coal, oil, gas) release more greenhouse gases compared to others (e.g. hydro, wind, solar, nuclear) [8]. Perhaps unsurprisingly, there are heated disagreements over whether the energy fueling the massive mining farms around the world are predominantly greener than average, or worse. The current estimate with regards to percentage of total hashing energy coming from renewables is 39% [11]. However, even with renewables, unless the source is an off-grid, or otherwise underutilized plant, one must also take displaced renewables into account [12]. Footnote 5. has more information.
  2. It’s important to note, that while there are some very useful tools out there to calculate kWh and KgCO2 estimations for ETH wallets [9], these only look at the transactions that a ETH wallet was directly involved in (e.g. transfer of ETH funds). However, minting, sales and bids on an NFT are not necessarily linked to the authors’ ETH account depending on the platform used, so these tools will miss them. Instead, to calculate the footprint of an NFT, one must look at the smart-contract(s) involved. (Note that there may be more than one smart-contract involved for a single NFT, as it is on SuperRare: one contract for minting and transfers, another contract for bids).
  3. It might be more accurate to compute the energy consumption per unit of Gas at the time of the transaction, by using historical figures. However I don’t do this, and I use recent figures. The reason for this is because I’m less interested in the footprint of past NFTs, and I’m more interested in the footprint of current NFTs.
  4. Due to sheer volume, simple, typical, daily, activities also add up. A single email is thought to produce in order of ~1–10g of CO2. But just the CO2 emissions of spam emails were estimated to be around 3 billion KWh per year according to a report in 2009 [15].
  5. (moved to main body)



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