CO2ken

Contracts

CO2ken has two core Solidity contracts: the ledger contract. which tracks the minting and retiring of CO2kens (co2ken.sol) and a storage contract (co2kenData.sol), which holds - most importantly - an ownable CO2ken price value.

co2ken.sol

• mint(string memory ipfsHash, uint256 amountTokens) public onlyOwner(): allows the owner to create new CO2kens
• withdraw() public onlyOwner(): allows the owner to withdraw monies received to the contract
• offsetCarbon(uint256 payment) public: allows anyone to pay a dollar-denominated value into the contract to offset carbon
• offsetCarbonTons(uint256 tons) public: allows anyone to pay a ton CO2 denominated value into the contract to offset carbon

co2kenData.sol

• setCO2kenPrice(uint256 _co2kenPrice) public onlyOwner(): allows the owner to set the price of CO2kens

polluter.sol

Contains the Green contract that can be inherited by others to make available the offset() modifier.

• offset(uint256 offsetThreshold): a modifier that accepts a threshold parameter to offset all accumulated carbon emissions of the function once it is crossed (batching)

Also contains the Polluter contract which is Green to demonstrate modifier functionality.

Contract Addresses

Rinkeby

CO2kenData - 0x127AE08f45d687dA7887ceA369F2f4D95cb9baf2

CO2ken (for demo) - 0x6a1B0C693DD4AA99bA8E93247AA221Fb30525Cfe

Polluter (is Green) - 0x57AaFA7eA3D66e2C9540d455BDBe093De9DB6bf4

WEENUS (test ERC20) - collect test WEENUS by visiting https://rinkeby.etherscan.io/token/0xaff4481d10270f50f203e0763e2597776068cbc5#writeContract connecting web3 wallet and write to drip()

The Graph

Setup and Deployment

To setup and deploy subgraph run the following commands:

npm run codegen

graph auth https://api.thegraph.com/deploy/ GRAPH_AUTH_TOKEN

graph deploy --debug --node https://api.thegraph.com/deploy/ --ipfs https://api.thegraph.com/ipfs/ benesjan/CO2ken

Requesting data

The Graph uses GraphQL API. To get a balance of purchased CO2kens for address "0xaa81ca5483020798f1a8834e1fb227e1c02c8ede" run:

curl -X POST -H "Content-Type: application/json" --data '{ "query": "{ userBalances(id: "0xaa81ca5483020798f1a8834e1fb227e1c02c8ede") { balance } }" }' https://api.thegraph.com/subgraphs/name/benesjan/co2ken