Enhanced Geothermal Output Calculator
Calculate power output from an enhanced geothermal system (EGS).
About this calculator
Enhanced geothermal systems pump water down into hot, dry rock, let it pick up heat, and bring it back up to drive a turbine — this calculator models that chain from raw thermal energy down to net electricity. It first computes the thermal power carried by the produced fluid using Q = ṁ·Cp·ΔT (flow rate times water's specific heat, 4.186 kJ/kg·K, times the temperature drop between the reservoir and the reinjected fluid). That thermal power is then capped by physics: the calculator computes the Carnot efficiency limit — the theoretical maximum for turning heat into work between the reservoir and reinjection temperatures (both converted to absolute Kelvin) — and multiplies it by your turbine's efficiency to get an actual conversion efficiency. This treats turbine efficiency as a fraction of the unreachable Carnot ceiling, which is a common simplified stand-in for the messier real-world losses in binary-cycle or flash-steam plants, rather than a first-principles thermodynamic cycle model.
Net electric output per well then subtracts parasitic load — the power the pumps, fans, and auxiliaries consume just to run the plant — before multiplying by well count for total plant output. Annual output assumes a fixed 95% availability factor (roughly 8,322 of 8,760 hours per year), which is a reasonable industry rule of thumb but won't match a specific plant's actual uptime. Because deltaT and Carnot efficiency both hinge on the gap between reservoir and reinjection temperature, the single most consequential input is how aggressively you reinject — a lower reinjection temperature raises both figures but also strains the equipment and the reservoir's long-term heat recovery.
Inputs
Results
Net Power per Well
7.12 MW
Total Plant Output
21.35 MW
How to Use This Calculator
- Enter the reservoir temperature and the production flow rate per well.
- Enter the reinjection temperature to set the temperature drop across the system.
- Set the turbine efficiency and parasitic load percentages.
- Enter the number of production wells in the plant.
- Review the net power per well and total plant output in MW, along with thermal power, annual output, and conversion efficiency.
How the result changes with Reservoir Temperature
| Reservoir Temperature | Net Power per Well | Total Plant Output |
|---|---|---|
| 100 | 0.48 MW | 1.44 MW |
| 150 | 3.01 MW | 9.04 MW |
| 300 | 18.39 MW | 55.17 MW |
| 400 | 32.23 MW | 96.7 MW |
What each input means
- Reservoir Temperature
- Temperature of the geothermal reservoir fluid.
- Production Flow Rate
- Flow rate per production well in liters per second.
- Reinjection Temperature
- Temperature of fluid reinjected into the reservoir.
- Turbine Efficiency
- Turbine isentropic efficiency.
- Parasitic Load
- Power consumed by pumps, fans, and plant auxiliaries.
- Production Wells
- Number of production wells.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersReservoir Temperature = 200, Production Flow Rate = 80, Reinjection Temperature = 70, Turbine Efficiency = 70 = 6 input(s) provided
- Calculate Net Power per WellNet Power per Well7.12 = 7.12
- Calculate Total Plant OutputTotal Plant Output21.35 = 21.35
- Calculate Thermal Power per WellThermal Power per Well43.53 = 43.53
- Calculate Annual Output per WellAnnual Output per Well59227 = 59227
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What is the Carnot efficiency limit and why does it matter here?
Carnot efficiency is the theoretical maximum fraction of heat that can ever be converted to work between two temperatures, computed here as 1 minus the reinjection temperature over the reservoir temperature (both in absolute Kelvin). The calculator multiplies that ceiling by your turbine efficiency to get the actual conversion efficiency, so no matter how efficient the turbine itself is, the plant can never convert more of the thermal power to electricity than physics allows for that particular temperature gap.
Why does lowering the reinjection temperature increase output — and what's the tradeoff?
A lower reinjection temperature widens ΔT (raising thermal power) and simultaneously raises the Carnot ceiling (since Tc/Th shrinks), so both drivers of electricity output move in your favor. The tradeoff is real-world, not modeled here: reinjecting cooler fluid strains pumps and piping and can cool the reservoir faster over time, hurting the resource's long-term productivity.
What does parasitic load represent, and why is it subtracted after conversion?
Parasitic load is the share of gross generated electricity consumed on-site just to keep the plant running — circulation pumps, cooling fans, and other auxiliaries. The calculator computes gross electric output first (thermal power times conversion efficiency), then multiplies by (1 minus parasitic load) to get the net electricity actually available to sell or use, which is always lower than the gross figure.
Where does the 95% figure in the annual output calculation come from?
It's a fixed availability factor representing roughly 8,322 of the year's 8,760 hours, meant to approximate a well-run plant's actual uptime after accounting for maintenance and downtime. It's a reasonable industry assumption but isn't calculated from any input you provide, so a specific plant's real annual output could differ if its actual availability is higher or lower than 95%.
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