How it works
Four steps, all on public data.
1. Find your grid
Your ZIP code (or your connection's approximate region, from Cloudflare) picks the state, and the state picks its main balancing authority. You can pick another grid from the list.
2. Read the fuel mix
Every hour we pull the EIA-930 data: megawatt-hours from coal, gas, oil, nuclear, wind, solar, hydro and others, for every U.S. balancing authority.
3. Price the carbon
Each fuel's share × EIA's pounds of CO2 per kWh (coal 2.31, gas 0.96, petroleum 2.46; others 0) gives each hour's intensity.
4. Find the pattern
The latest days are averaged by hour of day and turned to your time zone. The greenest segment is the cleanest hour.