Carbon methodology · v1.0

How carbon intensity
is estimated.

A transparent, reproducible estimate—not a claim of meter-level precision. Gridmix Atlas combines reported generation with a fixed lifecycle factor for each fuel.

THE CALCULATION
Σ (generationfuel × factorfuel)÷Σ generationall fuels= gCO₂e/kWh

Each MW observation is multiplied by its interval duration to get MWh. Negative generation is excluded from the carbon total. The same calculation is applied at every displayed time range.

Factor library

Lifecycle emission
factors.

Factors are central estimates in grams of CO₂-equivalent per kWh. They include lifecycle effects for consistency across fossil, renewable, and nuclear generation.

Fuel familyMapped labelsgCO₂e/kWhBasis
WindWind11Lifecycle
NuclearNuclear12Lifecycle
HydroHydro / Large Hydro / Small hydro24Lifecycle
GeothermalGeothermal38Lifecycle
SolarSolar45Lifecycle
BiomassBiomass / Biogas / Bioenergy230Lifecycle
ImportsImports390Default when origin is unknown
Natural gasNatural Gas / Gas490Lifecycle
OilOil650Lifecycle
Other fossilOther Fossil700Conservative blend
CoalCoal / Coal and Lignite820Lifecycle
StorageEnergy Storage0Counted at charging generation
01

Production-based

The estimate follows electricity reported inside the selected system. It is not a consumption-based flow model and does not trace imported power to its originating plant.

02

Average, not marginal

This is the weighted average of the visible mix. It does not estimate which generator would respond to one additional kWh of demand.

03

Storage accounting

Storage is assigned zero at discharge because charging emissions are already present in the generating mix. Without charge-source tracing, this can make short windows look cleaner than they truly are.

04

Source coverage varies

Rooftop solar, embedded generation, interchange, and storage may be omitted or grouped differently by each operator. The data-health panel reports interval completeness, not unreported resources.

Primary references
NREL lifecycle factor datasetQuartile estimates by technology and lifecycle phase ↗U.S. EIA power-sector CO₂ factorsObserved fuel-specific combustion emissions ↗EIA coefficient methodologyHow fuel carbon coefficients are derived ↗