Sources
Start with the underlying data.
Greener Numbers links material claims and calculator methodology to primary public sources wherever practical.
Federal energy data
The U.S. Energy Information Administration is the principal source for electricity sales, revenue, average retail price, fuel, and energy spending context.
Transportation and efficiency
The U.S. Department of Energy and its Alternative Fuels Data Center provide public methodology and comparison context.
Economic context
Bureau of Labor Statistics and FRED series may be added for energy-inflation context after source-specific review.