A factory can buy enough solar certificates to say "100% renewable" while running on gas every night. HourMatch issues renewable certificates per plant per hour on a shared ledger, lets each one be retired once and only against the same hour's metered use, then checks any green-power claim against that ledger.
Why it matters: in a study of 115 companies with science-based targets, about two thirds of the Scope 2 cuts they reported for 2015 to 2019 came from certificates rather than real reductions (Bjørn et al., Nature Climate Change, 2022). The GHG Protocol opened a public consultation on hourly matching in 2025.
Demo data. Every company, power plant, contract and wallet here is fictional. The hourly solar, wind and hydro output curves are real: Taiwan Power Company open data, 6 to 12 October 2026 (data.gov.tw dataset 8931), scaled down to plant size.
Designed for the demo. Each company's yearly-style certificate volume was set on purpose to a little over its use (Northbay Fab 103%, Harbor Office 105%, Cloudline 104%), so that "100% renewable" is true on paper. The hour-by-hour shares are not tuned: they are whatever the real Taipower curves produce against those loads.
Where each number comes from.browser ledger numbers are computed on this page by a JavaScript copy of the contract rules, for the whole demo week or for your own files. Sepolia numbers are read from the contract on the Ethereum Sepolia test network, where one demo day (8 October) is written. The test suite replays the full week on the contract and checks that both give identical results.
Check your own hourly data
Files are read in your browser. Nothing is uploaded, stored or written on chain. Times without an offset are read as Taiwan time (UTC+8). Download the samples to see the format; they reproduce the demo company Northbay Fab.
What the shared ledger refused this week browser ledger
On Ethereum Sepolia, with separate wallets Sepolia
Evaluation: what it tests and what it does not
Taiwan context 台灣制度對照
Why a blockchain and not a database, and what it does not guarantee
One retirement state, many issuersTwo authorized issuers write certificates into one contract, and both sets count against the same "matched" counter for each company and hour. A kWh retired through one issuer cannot be claimed again through the other.
Anyone can re-check a claimmatchedBps(company, from, to) is a public read. An NGO, an auditor or a customer recomputes the share without an account or a data request. The button above does exactly that.
Anchored claims stay as writtenA company anchors the hash of its own claim from its own wallet. The share stored next to it is computed by the contract at that block.
Trust model, stated precisely
Once a transaction is in a Sepolia block, nobody can edit or delete it, including the operator. The contract has no function that changes a balance, a retirement or an anchored record after the fact, and it cannot be upgraded.
The operator decides which issuers are authorized and writes the metered use. Wrong meter data gives a wrong share. A meter correction is possible, is a public event, and can never go below what is already matched. In a real system meter data would come from the grid operator and the issuer list would be under multi-party control.
Only the wallet bound to a company can retire certificates or anchor claims for it. The binding is set by the operator.
Sepolia is a public test network with no money at stake. This is a prototype, not audited, and has no legal standing next to Taiwan's official registry.
If a single national registry published hourly certificates and opened read access, it could do most of this without a chain. Taiwan's registry issues certificates per 1,000 kWh with no hour today.