Case Study: 500 MWe EGS Project Modeled on Fervo Cape Station

The GEOPHIRES example Fervo_Project_Cape-4 is a case study of a 500 MWe EGS Project modeled on Fervo Cape Station with its April 2025-announced upsizing from 400 MW to 500 MW. Case study inputs are formulated using a combination of publicly available data, extrapolations, and estimates. Financial results are calculated using the SAM Single Owner PPA Economic Model.

Key case study results include LCOE = $78.8/MWh and CAPEX = $4650/kW.

Click here to interactively explore the case study in the GEOPHIRES web interface.

Approach & Methodology

The case study is constructed to be representative of a 500 MWe EGS project similar to Cape Station, although it is not intended to be an exact facsimile. This is because not all relevant data points are publicly available (e.g. full PPA terms) while others may not be applicable outside of Cape Station’s first-of-a-kind status (such as drilling costs of initial wells which were more expensive at $4.8–9.4M per well).

Exact values were used for publicly available technical and engineering parameters, such as reservoir density (2800 kg/m³). Some technical parameters were inferred with high confidence from publicly available data, such as geothermal gradient (74 ℃/km) and well diameter. Other parameters were extrapolated or speculatively estimated based on plausibility and/or compatibility with known results, such as number of doublets.

The Inputs and Results tables below document key assumptions, inputs, and a comparison of results with reference values. Note that these are not the complete sets of inputs and results, which are available in source code and the web interface.

Inputs

See Fervo_Project_Cape-4.txt in source code for the full set of inputs.

Economic Parameters

Parameter	Input Value(s)	Source
Economic Model	SAM Single Owner PPA	The SAM Single Owner PPA economic model is used to calculate financial results including LCOE, NPV, IRR, and pro-forma cash flow analysis. See GEOPHIRES documentation of SAM Economic Models for details on how System Advisor Model financial models are integrated into GEOPHIRES.
Inflation Rate	2.3%	US inflation rate as of April 2025
PPA Price	Starting at 9.5 cents/kWh, escalating to 10 cents/kWh by project year 11	Upper end of ranges given in 2024 NREL ATB (NREL, 2024). Both PPAs ‘firm for 10 years at less than $100/MWh’ estimate given in a podcast.
Well Drilling Cost Correlation & Adjustment Factor	Vertical large baseline correlation + adjustment factor = 0.84 to align with Fervo claimed drilling costs of <$4M/well	Akindipe & Witter, 2025; Latimer, 2025.
Reservoir Stimulation Capital Cost Adjustment Factor	2.66	Estimated cost of ~$2M per well. Typical range for Nth-of-kind projects may be $0.5–2M.
Capital Cost for Power Plant for Electricity Generation	$1900/kW	US DOE, 2021.
Discount Rate	12%	Typical discount rates for high-risk projects may be 12–15%
Inflated Bond Interest Rate	5.6%	Typical debt annual interest rate
Fraction of Investment in Bonds (percent debt vs. equity)	60%	Approximate remaining percentage of CAPEX with $1 billion sponsor equity per Matson, 2024. Note that this source says that Fervo ultimately wants to target “15% sponsor equity, 15% bridge loan, and 70% construction to term loans”, but this case study does not attempt to model that capital structure.
Exploration Capital Cost	$30M	Estimate significantly higher exploration costs than default correlation in consideration of potential risks associated with second/third/fourth-of-a-kind EGS projects
Investment Tax Credit Rate (ITC)	30%	Same as 400 MWe case study (Fervo_Project_Cape-3)
Inflation Rate During Construction (additional indirect capital cost)	15%	Estimate high indirect capital costs in consideration of potential risks associated with unforeseen engineering challenges or construction delays

Technical & Engineering Parameters

Parameter	Input Value(s)	Source
Plant Lifetime	30 years	30-year well life per Fervo Energy, 2025 (Geothermal Mythbusting: Water Use and Impacts).
Well diameter	9⅝ inches	Next standard size up from 7”, implied by announcement of “increasing casing diameter”
Flow Rate per Production Well	107 kg/s	Fercho et al, 2025 models reservoir performance using 100 kg/s per well. The announced increased casing diameter implies higher flow rates, so the case study uses the maximum flow rate achieved at Cape Station of 107 kg/s per Fervo Energy, 2024.
Number of Doublets	59	Estimate based on extrapolation from previous case studies including Project Red and Fervo_Project_Cape-3
Number of Fractures per well	102	Estimate. (Note this is not a direct GEOPHIRES input parameter but was used to calculate other case study GEOPHIRES input parameters such as reservoir volume.)
Fracture Separation	18 m	Per Norbeck et al, 2024: lateral length is 4700 ft = 1432 m. Dividing 1432 by 80 = ~18 m fracture spacing.
Fracture Geometry	165.3 m × 165.3 m (Square)	Extrapolated from 30 million ft² fracture surface area per well per Fercho et al, 2025.
Reservoir Volume	5,418,039,158 m³	Calculated from fracture area (27,324.09 m²) × fracture separation (18 m) × targeted number of fractures per well (102)
Water Loss Rate	15%	Water loss rate is conservatively estimated to be between 10 and 20%. Other estimates and some simulations may suggest a significantly lower water loss rate than this conservative estimate. See Geothermal Mythbusting: Water Use and Impacts (Fervo Energy, 2025).
Maximum Drawdown	0.0153	Tuned to keep minimum net electricity generation ≥ 500 MWe and thermal breakthrough requiring redrilling occurring every 5–10 years
Reservoir Impedance	0.001565 GPa.s/m³	Yields ~15% initial pumping power/net installed power
Injection Temperature	53.6 ℃	Calibrated with GEOPHIRES model-calculated reinjection temperature (Beckers & McCabe, 2019). Close to upper bound of Project Red injection temperatures (75–125℉; 23.89–51.67℃) (Norbeck & Latimer, 2023).

Results

See Fervo_Project_Cape-4.out in source code for the complete results.

Economic Results

Metric	Result Value	Reference Value(s)	Reference Source
LCOE	$78.8/MWh	$80/MWh	Horne et al, 2025
Project capital costs: Total CAPEX	$2.86B
Project capital costs: $/kW	$4650/kW (based on maximum total electricity generation)	$4500/kW, $3000–$6000/kW	Horne et al, 2025; Latimer, 2025.
Well Drilling and Completion Cost	$3.96M/well	$<4M/well	Latimer, 2025.
WACC	8.3%	8.3%	Matson, 2024.
After-tax IRR	28%	15–25%	Typical levered returns for energy projects

Technical & Engineering Results

Metric	Result Value	Reference Value(s)	Reference Source
Minimum Net Electricity Generation	503 MW	500 MW	Fervo Energy, 2025. The 500 MW PPA is interpreted to mean that Cape Station’s net electricity generation must never fall below 500 MWe.
Maximum Total Electricity Generation	615 MW		Actual maximum total generation may be bounded or constrained by modular power plant design not modeled in this case study. For example, a modular design with 50MW units may constrain maximum total generation to 600 MW.
Number of times redrilling	3	3–6	Redrilling expected to be required within 5–10 years of project start
Average Production Temperature	199℃	204℃, 190.6–198.6℃ (optimal plant operating range)	Trent, 2024; Norbeck et al, 2024.
Total fracture surface area per production well	2.787×10⁶ m²	2.787×10⁶ m² (30 million ft² per well)	Fercho et al, 2025.

Uncertainty & Sensitivities

Given the methodological approach, including speculative estimation of some input parameters, and lack of real-world reference data for comparison, the case study results are subject to uncertainty. This case study does not attempt to quantify uncertainties, but sensitivity analysis may be included in future updates. Users may wish to perform their own sensitivity analysis using GEOPHIRES’s Monte Carlo simulation module or other data analysis tools.

References

Akindipe, D. and Witter. E. (2025). “2025 Geothermal Drilling Cost Curves Update”. https://pangea.stanford.edu/ERE/db/GeoConf/papers/SGW/2025/Akindipe.pdf?t=1740084555

Beckers, K., McCabe, K. (2019) GEOPHIRES v2.0: updated geothermal techno-economic simulation tool. Geotherm Energy 7,5. https://doi.org/10.1186/s40517-019-0119-6

Fercho, S., Norbeck, J., Dadi, S., Matson, G., Borell, J., McConville, E., Webb, S., Bowie, C., & Rhodes, G. (2025). Update on the geology, temperature, fracturing, and resource potential at the Cape Geothermal Project informed by data acquired from the drilling of additional horizontal EGS wells. Proceedings of the 50th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA. https://pangea.stanford.edu/ERE/pdf/IGAstandard/SGW/2025/Fercho.pdf

Fervo Energy. (2025, March 31). Geothermal Mythbusting: Water Use and Impacts. https://fervoenergy.com/geothermal-mythbusting-water-use-and-impacts/

Fervo Energy. (2025, April 15). Fervo Energy Announces 31 MW Power Purchase Agreement with Shell Energy. https://fervoenergy.com/fervo-energy-announces-31-mw-power-purchase-agreement-with-shell-energy/

Fervo Energy. (2024, September 10). Fervo Energy’s Record-Breaking Production Results Showcase Rapid Scale Up of Enhanced Geothermal. https://www.businesswire.com/news/home/20240910997008/en/Fervo-Energys-Record-Breaking-Production-Results-Showcase-Rapid-Scale-Up-of-Enhanced-Geothermal

Horne, R., Genter, A., McClure, M. et al. (2025) Enhanced geothermal systems for clean firm energy generation. Nat. Rev. Clean Technol. 1, 148–160. https://doi.org/10.1038/s44359-024-00019-9

Jacobs, Trent. (2024, September 16). Fervo and FORGE Report Breakthrough Test Results, Signaling More Progress for Enhanced Geothermal. https://jpt.spe.org/fervo-and-forge-report-breakthrough-test-results-signaling-more-progress-for-enhanced-geothermal

Latimer, T. (2025, February 12). Catching up with enhanced geothermal (D. Roberts, Interviewer). https://www.volts.wtf/p/catching-up-with-enhanced-geothermal

Matson, M. (2024, September 11). Fervo Energy Technology Day 2024: Entering “the Geothermal Decade” with Next-Generation Geothermal Energy. https://www.linkedin.com/pulse/fervo-energy-technology-day-2024-entering-geothermal-decade-matson-n4stc/

NREL. (2024). Annual Technology Baseline: Recent Public Geothermal Power Purchase Agreement Pricing. https://atb.nrel.gov/electricity/2024/geothermal

Norbeck, J., Gradl, C., Latimer, T. (2024, September 10). Deployment of Enhanced Geothermal System Technology Leads to Rapid Cost Reductions and Performance Improvements. https://doi.org/10.31223/X5VH8C

Norbeck J., Latimer T. (2023). Commercial-Scale Demonstration of a First-of-a-Kind Enhanced Geothermal System. https://doi.org/10.31223/X52X0B

US DOE. (2021). Combined Heat and Power Technology Fact Sheet Series: Waste Heat to Power. https://betterbuildingssolutioncenter.energy.gov/sites/default/files/attachments/Waste_Heat_to_Power_Fact_Sheet.pdf