Gas token arbitrage: the CHI and GST2 refund loop on Ethereum

Ethereum transaction fees have always been a moving target, but few users realise that a secondary market exists around the refund mechanism itself. Sophisticated traders and automated bots do not simply pay gas; they mint, hold, and burn specialised tokens designed to absorb part of the network's refund pool.

Gas tokens turn the Ethereum Virtual Machine's storage refund rule into a tradable commodity. By creating and later deleting contract storage, users can bank a rebate that is paid in priority fees and base fees. The two most prominent implementations, 1inch's CHI and the original GasToken project's GST2, have built an entire arbitrage economy around this quirk, reshaping how blocks are filled when the base fee drops sharply.

The origin of gas tokens and their original design

The GasToken project launched in 2017 as an experiment in tokenising storage refunds. Users could mint GST or GST2 tokens when gas prices were low by populating new storage slots in a smart contract, paying the upfront cost of writing data on-chain. When prices rose, those tokens could be burned, deleting the storage and triggering a refund paid by the network to the transaction's caller.

This design captured a fundamental truth of EVM economics: creating storage is expensive, while deleting storage once offered up to a half-refund. The contract acted as a voucher, deferring the refund until it became economically attractive. 1inch later launched CHI with optimised minting and burning logic, packaging the same idea into a token that composes cleanly with its DEX aggregator routes.

How CHI and GST2 capture refund value

The mechanics rely on EIP-2200 net gas metering, where the refund counter for a transaction reduces the actual gas consumed. When a user burns CHI or GST2 inside a swap, the refund is applied before the priority fee is calculated, effectively subsidising the trade. In practice, a swap that costs 200,000 gas can settle for the equivalent of 140,000 gas if enough tokens are burned.

Because refund capacity is capped per block, the tokens themselves carry a market price that fluctuates with congestion. During peak demand, CHI can trade at several gwei per token on Uniswap or Curve pools. During quiet blocks, the price collapses because there is little reason to mint. This price discovery is where keen traders extract value beyond a simple swap discount.

Arbitrage windows when base fees collapse

The most lucrative moments arrive when Ethereum's base fee crashes following the post-London EIP-1559 adjustment mechanism. After a few empty blocks, the base fee can halve every few seconds, creating windows where minting storage becomes almost free. Bots monitor mempool data and base fee history to mint CHI aggressively during these dips, then list the tokens for sale as congestion returns.

This is genuine arbitrage in the truest sense: the same instrument carries different implied values across the spot token price, the refund schedule, and the prevailing base fee. Searchers and MEV bots compete to be first to mint and first to list, which is why gas token liquidity is usually deepest on decentralised venues rather than centralised order books.

The Australian angle: fees in AUD and local exchange habits

For Australian traders routing through Swyftx, BTC Markets, or Independent Reserve, the refund economics land differently. A 30% effective discount on an Ethereum swap, when translated into AUD, can mean the difference between a profitable and a loss-making trade on smaller capital allocations. ASIC's ongoing scrutiny of crypto product distribution has pushed local exchanges toward clearer fee disclosures, but on-chain rebates still escape that reporting.

The Australian Taxation Office treats crypto-to-crypto swaps as taxable events, regardless of whether a gas token rebate was involved. That means burning CHI inside a swap does not magically neutralise the cost basis calculation; traders still need to record the AUD value at the time of disposal. A common mistake among Sydney and Melbourne-based DeFi users is to assume that cheaper gas translates into a smaller taxable gain, which is not how the ATO frames it.

Energy footprint and the mining connection

Refund tokens also sit inside a broader conversation about the environmental cost of proof-of-work chains. Ethereum's move to proof-of-stake has reduced its direct energy exposure, but the arbitrage bots that mint and burn CHI still influence how blocks are constructed on any remaining PoW network. Coverage of the hidden environmental cost of bitcoin mining often overlooks how much of the noise on legacy chains actually comes from refund-token farming rather than genuine transfers.

This is not an abstract concern for Australian operators. Several Perth-based mining outfits have repurposed older hardware toward renewable-heavy grids, and the marginal economics of every block depend heavily on whether the included transactions are arbitrage-driven or organic. Refund token activity inflates block sizes without contributing proportional settlement value, which skews energy-per-transaction metrics upward.

Practical playbook for active Ethereum users

For users who actually transact, the rules are simpler than the bot economy suggests. Mint CHI or GST2 when the base fee sits below roughly 20 gwei and the network has been quiet for several blocks. Hold the tokens until base fee rises above 60 gwei, then burn them inside any high-value swap or contract interaction where the refund meaningfully offsets the gas cost.

Track the CHI/gwei ratio on a dashboard before deciding to mint. If the ratio is already above parity, the trade is crowded and the upside has been priced in. Local tools like Etherscan's gas tracker, set to display in Australian time, give a clearer picture than global charts because peak congestion in AUD trading hours often differs from Asian or US peaks.

The real takeaway is that Ethereum's fee market is no longer a single price; it is a layered system of base fees, priority fees, and refund token prices that interact in real time. Treating the three as separate inputs, rather than one bundled cost, is how active users keep more of their AUD when the network gets busy.