megawatt.fun

Sources

Every number on the guide, where it comes from, and how it was worked out.

  1. The continuous formula is the interpolation usually credited to Carl Sagan. Gray (2020) shows it appears in his prose, not as an explicit equation. Gray, The Astronomical Journal (2020). ↩
  2. 2024 world primary energy, 176,737 TWh, divided by 8,784 hours = 20.1 TW. Our World in Data energy dataset (EIA and Energy Institute); saved copy: kardashev-baseline.json, retrieved 21 September 2026. ↩
  3. Our World in Data, Energy use per person vs GDP per capita: total energy supply per person (Energy Institute Statistical Review 2026 and other sources) and GDP per capita, PPP (World Bank et al.). Latest year per country, 191 countries, retrieved 28 September 2026. Correlation computed on log10 values. Saved copy: energy-gdp.json. ↩
  4. Capacity factors for 2025, US utility-scale plants: nuclear 91.0%, wind 34.2%, solar PV 24.4%. EIA, Electric Power Monthly, Table 6.07.B. Solar runs less often in cloudier and higher-latitude places, so the solar count here is a floor. ↩
  5. Unit sizes: average new onshore wind turbine 6.16 MW in 2025, GWEC Global Wind Report 2026; AP1000 reactor 1,110 MW net, Westinghouse. ↩
  6. World fleets at the end of 2025: solar 2,392 GW, wind 1,291 GW. Added in 2025: solar 511 GW, wind 158.7 GW, both records. IRENA, Renewable Capacity Statistics 2026. ↩
  7. Operating reactors: 404 on 1 January 2026 per the World Nuclear Industry Status Report, 413 per IAEA PRIS. They count idle reactors differently; we use 413. All assumptions: build-assumptions.json. ↩
  8. Solar land: 8.9 acres per MW of capacity, total site area, US average. NREL, Land-Use Requirements for Solar Power Plants in the United States (Ong et al., 2013). ↩
  9. Texas total area 695,662 km². US Census Bureau, State Area Measurements. ↩
  10. Base Core sizes 39.2 kWh and 78.4 kWh, pv magazine USA, 4 August 2026. The homes count is an estimate: it assumes 12 hours of the new power has to come out of storage, using the 39.2 kWh size. ↩
  11. Illustrative day: the demand and solar shapes are drawn to show the timing mismatch, not taken from a real grid. The math on top of them (what charges, what's wasted, what's short) is exact. ↩
  12. Base Power, Base Core and How it works. ↩
  13. ERCOT, About ERCOT. ↩
  14. ERCOT day-ahead hub-average prices, 13 August 2026, from ERCOT's public system-wide prices feed; saved copy: CSV. ↩
  15. This site's own capex model and README: $150/kWh over a 15-year life, one cycle a day. Energy-only floor, not full battery value. ↩