Green NFTs
Moving resource-intensive NFT operations to an energy-efficient chain
Published 06.24.2021
As the transition towards Ethereum 2.0 continues to progress, the xDai network is supporting and closely following the shift to Proof-of Stake and increased energy efficiency. The required architectural overhaul is complicated and needs to be done with absolute care considering the value tied to the Ethereum ecosystem. It should not be rushed.
However, at the same time global emissions continue to rise, the earth continues to swelter, and Ethereum energy consumption continues to grow, currently surpassing the energy expenditure of Portugal. This problem is growing more dire by the day, and we all know climate change isn’t following the same “eventual” Ethereum 2.0 timeline. This issue needs to be addressed head-on, before Eth 2.0 is fully rolled out.
Fortunately, it is possible to take action now by moving some types of resource-intensive Ethereum operations to the xDai network.

NFT Operations are Gas

While we wait and iterate towards a new energy-efficient Ethereum, there are ways projects can vastly reduce carbon footprints right now, and still maintain compatibility with Ethereum for easy reintroduction once sustainability is achieved. NFTs on xDai are a great place to start.
On Ethereum and other EVM blockchains like xDai, NFT minting is a gas-intensive process relative to regular transactions. In addition to NFT creation, the bidding process, transfers, sales and other possible features all add up to additional gas expenditure.
In this thorough analysis by Memo Akten, the creator of the now defunct site http://cryptoart.wtf, the average carbon footprint of a single NFT on Ethereum is around 340kWh and 211 KgCO2. This is the equivalent of an EU resident’s total electric power consumption for more than 1 month!
When breaking down NFT energy needs, Akten looked at gas expenditure across a range of NFT-related processes. At the time, he determined the average energy consumption for an NFT was approximately 10x the cost of a simple transaction.
At the time of his analysis, in December 2020, a single Ethereum (ETH) transaction was estimated to have a footprint averaging around 35 kWh. In June, 2021, this has increased by more than 3x to 123.02 kWh! This increase is a result of more usage/price gains and subsequent mining. Akten found the footprint for the average NFT was 340kWh. In June 2021 this equates to 1,190 kWh per NFT on Ethereum.
Many artists and others appalled by this impact continue to mint and trade on Ethereum while trying to offset these enormous emissions. Beeple estimates it costs about $5000 to offset just 1 of his collections. This is one way for wealthier artists to help assuage their guilt and have a positive impact, but what if the carbon doesn’t need to be generated in the first place? What if instead of offsetting carbon emissions we offset the entire NFT process by moving it to a green, energy-efficient chain?

Moving to xDai

Moving this same transaction to xDai results in a huge and dramatic drop in energy expenditure. Since the xDai network already runs on Proof-of-Stake with a smaller group of nodes, energy usage is drastically reduced.
In an analysis done by Lab10, the average xDai transaction consumed 0.0000058 kwH of energy. Assuming the same 10x for an NFT-related transaction, the average energy expenditure for NFT related actions is 0.000058 kwH. Considering an energy-efficient CFL/LED (8 W) lightbulb uses 0.008 kWh per hour, it would take more than 137 NFT-based transactions (including minting, trading, selling etc) on xDai to equal 1 hour of light from the most energy-efficient lightbulb available on the market today. Using Akten’s analysis for Ethereum, a single NFT would require nearly 150,000 lightbulbs!!
Average kWh for 1 NFT group of operations
Equivalent low-watt lightbulb usage for 1 hour (.008 kWh)
NFTs can be traded, listed, bid-on, sold etc on xDai with support from tools and infrastructure already on-board. If projects need to bridge NFTs to the Ethereum mainnet they can do that as well, although this process uses the same amount of energy as minting an NFT on Ethereum. Projects can also wait for a more opportune time to bridge (when gas costs are lower, resulting in lower energy expenditure) or ideally wait for Eth2, where energy efficiency will be increased by 99+%!
As more projects and NFT users come to xDai, it makes sense to maintain a robust NFT ecosystem on xDai until Ethereum’s sustainable future is realized. xDai is committed to maintaining compatibility with Ethereum, and when sustainability is here any NFT can be sent back to the mainnet in an energy-efficient way as desired.
The effort to move NFT and other resource-intensive operations to xDai (it’s extremely easy from a code perspective due to Ethereum compatibility) is well worth the potential environmental costs of waiting and wishing for Eth2. Projects are beginning to take the lead and responsibility for their carbon footprints by minting NFTs directly on the xDai chain.

Projects using xDai for NFTs

Many projects have already moved some or all operations to xDai. Some were initially motivated by cost-savings, however the savings per tx have also translated into big energy savings. Below are a few of the many NFT-based projects using xDai to help offset their carbon footprints.
*Lightbulb hours saved based on Akten's analysis above of average energy requirements for NFT tokens on Ethereum.


POAPs are digital collectibles minted on xDai. Projects typically use POAPs for proof-of-attendance to events. Each badge serves as a cryptographic proof that someone has attended a function or event. There are currently 269581 addresses holding 359,263 POAPs on xDai.
Lightbulb Hours Saved ((359,263 * 148,750) - (359,263 * 0.0073)) = 53,440,368,627

​Crypto stamp​

Crypto stamp is a public project from the Austrian Post. The post mints digital postage stamps on the blockchain which are paired with physical postage stamps. Environmental concerns were a key component as to why the Crypto stamp project chose to mint and perform other operations (like color reveals) on xDai. There are 100,000 CS3 NFT stamps on xDai.
Lightbulb Hours Saved ((100,000 * 148,750) - (100,000 * 0.0073)) = 14,874,999,270


Gitcoin Kudos are NFTs minted and sent to others to show appreciation and build relationships. There are currently 80375 addresses holding 90,077 kudos on xDai.
Lightbulb Hours Saved ((90,077 * 148,750) - (90,077 * 0.0073)) = 13,398,953,092


Nifty.Ink allows users to draw and mint NFTs directly on xDai. These operations are typically even more resource-intensive than standard NFT operations. Nifty supports new users with a burner wallet and fun, easy interaction. There are currently 10,119 addresses holding 18,733 inks.
Lightbulb Hours Saved ((18,733 * 148,750) - (18,733 * 0.0073)) = 2,786,533,613

NFT Marketplaces

Marketplaces on xDai also support the sale and transfers of NFTs, further reducing carbon output. Some of the largest contributors to high energy expenditure on Ethereum are actually the marketplaces that handle NFT creation, bidding, selling and transfers. Popular marketplaces on xDai include:
  • ​Cargo: Create, share, sell and buy digital collectibles
  • ​Unique.one: NFT Marketplace
  • ​Eporio: NFT Marketplace
  • ​Unifty: NFT project hub for custom farms and collections.
A complete list is available here, and includes smaller, innovative NFT collectives pushing the boundaries.

Recycle or Toss?

Many people consider their carbon footprint when making everyday choices. Sometimes it is a bit more inconvenient to recycle a bottle than throw it away, to take public transport, use a cloth bag, or the myriad of other tradeoffs we make to support the environment. If you are a blockchain user, your transactional choices should also be considered in this equation. Starting to use xDai can also be a bit inconvenient ( custom MetaMask Network setup, we're looking at you
) but the impact is immediate and important on a global level.
While no single type of transaction is more or less responsible for Ethereum’s energy expenditure, moving resource intensive transactions like NFT minting to alternative, green PoS-based chains like xDai is a way to free up space, reduce congestion, and potentially influence energy output on the Ethereum mainnet.
The xDai team and community are very excited for Eth2 and the efficiency (and speed, cost reduction, decentralization etc) it will bring to the ecosystem. But it’s not here yet, and we can do our part right now to help alleviate some of the Eth1 problems causing harm to the environment. Using green chains when appropriate makes sense, and is a viable option available for users today.