How it works
Every year, for 25 years, the model asks one question: what’s the cheapest mix of power sources that still keeps the lights on, every hour?
These six sources compete every year — the model picks how much of each to build.
Where the data comes from
The model is grounded in six years of real US electricity data (2020–2025) — nearly 700,000 hourly readings across 13 regions, broken down by source.
The knobs you can turn
Three big levers, plus per-source cost dials, shape every run:
A price on carbon pollution that climbs every year, making gas and coal steadily more expensive.
How much more electricity the region needs each year.
The cost of borrowing to build new plants — this can make or break nuclear, which takes decades to pay off.
What happens every simulated year
Every source loses a slice of its capacity each year — older, longer-lived plants (like nuclear) lose less than younger ones.
The region needs more electricity than last year, by a set growth rate.
For each source, it picks how much new capacity to add — whatever combination keeps costs lowest.
Cheapest power goes first. Leftover power charges the battery; shortfalls draw it down. Anything still unmet is an outage.
Building, running, and any outages all cost money. The optimizer keeps adjusting until it finds the cheapest year.
Want the math behind each step? See the methodology page.
A few terms you'll see
MW is how big a power plant is. MWh is how much energy it actually produced. A big plant that rarely runs still makes little MWh.
How often a source actually runs, as a percent of the time. Nuclear: almost always. Solar: only when the sun's out.
Electricity demand that went unmet. A well-run scenario keeps this at zero.
Ready to explore? Check out the library of real runs, or compare two scenarios side by side.