Tokenized-Carbon Credit Marketplace (on Polygon/Matic)

【Introduction of the Tokenized-Carbon Credit Marketplace (on Polygon/Matic)】

• This is a smart contract and dApp that is the Tokenized-Carbon Credit Marketplace which allow to be able to claim, audit, buy/sell carbon credits in a single platform. (for incentivize and accelerating the CO2 emission reduction)
  • By that whole process is executed on this platform, it is able to keep transparency and traceability .
  • The Carbon Credit Tokens (CCTs) are used for representing amount of carbon credits. (The Carbon Credit Tokens is created as ERC20 token)
  • Green NFT is used for a proof of audit of CO2 reductions for a project
  • This smart contract is deployed on Polygon (previously Matic Network ) in order to save cost of transaction and realize faster transactions.

【Workflow】

• ① A project owner (e.g. organizations, corporations, etc...) register themself on this dApp.

• ② A auditor (e.g. the institutions to issue carbon credit) is registered on this dApp.

  • Only admin (deployer of smart contracts) can register a auditor.

• ③ A project owner claim CO2 reductions to a auditor.

• ④ Auditor audit (=approve) a claim from a project owner.

  • Once a claim is audited, the Green NFT and the Carbon Credit Tokens (CCTs) are given (=charged) into a project owner's wallet.
  • A Green NFT represents a proof of audit of CO2 reductions for a project that is claimed.
  • Given-Carbon Credit Tokens (CCTs) are same amount with audited-amount of CO2 reductions.

• ⑤ A project owner put a Green NFT (=proof of audit) and the Carbon Credit Tokens (CCTs) on sale.

• ⑥ A buyer can buy the Carbon Credit Tokens (CCTs) based on GreenNFT in the carbon credit marketplace.

  • Once buying process is successful, CCTs that are bought by a buyer will be transferred into a buyer's wallet. (※ At that time, a Green NFT is not transferred. A Green NFT is kept in the project owner's wallet as a proof of audit)
  • That buyer can sell CCTs bought in the marketplace as secondary sales.
  • Price rate of the Carbon Credit Tokens (CCTs) is 1 CCT = 1 MATIC

【Demo Video】

• https://youtu.be/LiMHJL8H2oA

【Versions】

• Versions are following below:
  • Solidity (Solc): v0.6.12
  • Truffle: v5.1.60
  • web3.js: v1.2.9
  • openzeppelin-solidity: v3.4.1
  • ganache-cli: v6.9.1 (ganache-core: 2.10.2)
  • Node.js: v11.15.0

【Setup】

Setup private network by using Ganache-CLI

1. Download Ganache-CLI from link below
   https://www.trufflesuite.com/ganache

2. Execute Ganache

$ ganache-cli -d

※ -d option is the option in order to be able to use same address on Ganache-CLI every time.

Setup wallet by using Metamask

1. Add MetaMask to browser (Chrome or FireFox or Opera or Brave)
   https://metamask.io/

2. Adjust appropriate newwork below (In case of deploying smart contract on local)

http://127.0.0.1:8545

2. Adjust appropriate newwork below (In case of deploying smart contract on Polygon's Mumbai testnet)

https://rpc-mumbai.maticvigil.com/

(More configuration detail is here: https://docs.matic.network/docs/develop/metamask/config-matic/ )

Setup backend

• In case of deploying smart contracts on local

$ npm run migrate:local

• In case of deploying smart contract on Matic's Mumbai testnet

$ npm run migrate:polygon_testnet

Setup frontend

1. NPM modules install

$ cd frontend
$ npm install

2. Execute command below in root directory.

$ npm run start

3. Access to browser by using link

http://127.0.0.1:3000

【References】

• Polygon (Previously Matic)

  • Mumbai testnet (with Truffle) https://docs.matic.network/docs/develop/truffle

  • Matic Fancet (include for Mumbai testnet) https://faucet.matic.network/

  • Set up MetaMask for Mumbai testnet:
    https://docs.matic.network/docs/develop/metamask/config-matic/

  • Workshop https://youtu.be/BT-UZBInh7w?t=697

  • Deposit ETH into Matic https://docs.matic.network/docs/develop/ethereum-matic/plasma/eth