Geothermal Calculator
Turn a volcano, geyser or any heat source into Steam Turbine power — or size an Aquatuner cooling loop and see how much of its power the turbines refund. Three modes: Power (heat → watts), Cooling (heat load → infrastructure), and Combined Loop (heat source + fixed turbine count → the chamber's equilibrium temperature). Verified against the live-game Steam Turbine and Aquatuner mechanics.
Uses this type's typical roll. For your exact roll, dial it in on the Geyser Calculator and read the heat there.
Recommended — the turbine's own 95 °C output water runs through radiant pipes inside it. Zero parasitic power.
Power maxes at 850 W/turbine at 200 °C; above that, power is flat but heat deletion keeps rising (run hotter only to delete more heat).
Turbines
Power
Active = build for the peak; average folds in 0% uptime (dormancy).
Water & mass balance
Dry / closed loop — the turbines recycle their own output water back to steam. Self-sustaining once primed (no bleed-off needed).
Steam Turbine power and Aquatuner cooling, done properly
The geothermal calculator has three modes. Power mode takes a heat source — any volcano or geyser from the game data, or a custom DTU/s input for magma biomes, rocket exhaust or anything else — and tells you how many Steam Turbines it can sustain, whether the limit is heat or steam mass, the gross and net watts (both for the active season and averaged over dormancy), and the water/mass balance of the loop. Cooling mode flips it around: give it a heat load — directly in DTU/s or as "cool X kg/s of an element from one temperature to another" — and it sizes the Aquatuners for each coolant, then works out the turbines that delete the Aquatuner's dumped heat and the power they refund, so you see the real net power cost of the cooling loop. Combined Loop mode is the real-build question the wiki tools skip: put a heat source and a fixed number of turbines on one steam chamber and it solves for the equilibrium temperature the chamber settles at — and warns you when it's undersized (temperature creeps away) or oversized (turbines stall at the activation floor).
Every number is built on the live-game mechanics: the Steam Turbine's linear 850 W power curve and 95 °C output, the 125 °C activation and 100 °C overheat thresholds, and the Aquatuner's flat 14 °C delta at 10 kg/s and 1,200 W. Turbine cooling is a mode choice — self-cooled by the turbine's own output water (the sane default, zero parasitic power) or Aquatuner-cooled — rather than an unconditional overhead tax. Coming from the Geyser Calculator? Its steam-turbine section links straight here with your geyser preloaded.
Geothermal calculator FAQ
- How much power does a Steam Turbine make in Oxygen Not Included?
- A Steam Turbine outputs up to 850 W, scaling linearly from 0 W at 95 °C to the full 850 W at 200 °C steam — power = 850 × (T − 95) ÷ 105, capped at 850 W. Above 200 °C the power stays flat at 850 W but the turbine keeps deleting more heat, so you only run hotter when heat deletion is the goal. Each turbine pumps up to 2 kg/s of steam across its five intake ports.
- Do I need an Aquatuner to cool a Steam Turbine?
- Usually no. The standard self-cooled design runs the turbine's own 95 °C output water through radiant pipes inside the turbine to keep it below its 100 °C overheat point — that costs zero extra power. An Aquatuner is only needed when the chamber runs very hot; the calculator lets you pick self-cooled (recommended) or Aquatuner-cooled and shows the parasitic power either way.
- Is a geothermal steam loop self-sustaining?
- For a dry heat source like a volcano the steam loop is closed — the turbines recycle their own 95 °C output water back into steam, so it is self-sustaining after a one-time prime with water. A condensable source such as a steam vent or hot water geyser adds mass to the loop, so it slowly gains water you need to bleed off. The calculator flags which case you are in.
- How many Aquatuners do I need, and how much power do the turbines refund?
- One Aquatuner removes SHC × 10 kg/s × 14 °C of heat per second — 585,060 DTU/s with water or polluted water, and 1,181,600 DTU/s with Super Coolant, all at 1,200 W. In Cooling mode the calculator sizes the Aquatuners for your heat load per coolant, then computes the Steam Turbines needed to delete the heat the Aquatuner dumps and the power they refund, giving the true net power cost of the loop.