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Comparison
Firm vs Intermittent Power
Firm power is available on demand; intermittent power depends on weather. Understanding the difference explains why a clean grid needs both — and where fusion fits.
- Firm
- Available on demand, any time
- Intermittent
- Weather- and time-dependent
- Grid need
- Firm capacity behind intermittent supply
- Fusion
- Firm, clean
The single most important distinction in modern grid planning is between firm and intermittent power. Firm generation is dependable — you can call on it whenever it's needed, day or night. Intermittent generation (wind, solar) is cheap and clean but delivers on nature's schedule, not the grid's.
| Dimension | Firm / Intermittent |
|---|---|
| Availability | On demand / weather-dependent |
| Examples | Fusion, fission, gas, geothermal, hydro / wind, solar |
| Grid role | Reliability backbone / low-cost bulk energy |
A grid can't run on intermittent supply alone — something firm must fill the gaps, and today that's mostly fossil fuels. The scarce, valuable thing in a decarbonizing grid is therefore firm clean power. That's the category fusion is built for. See what is firm power? and grid firming.