This case study – example name: Fervo_Project_Cape-4 – is a 500 MWe EGS Project modeled
on Fervo Cape Station with its April 2025-announced
upsizing from 400 MW to 500 MW,
using a combination of publicly available data, extrapolations, and estimates.
The case study is constructed to be representative of a 500 MWe EGS project similar to Cape Station, but 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 well diameter and geothermal gradient (74 ℃/km). Other parameters were extrapolated or speculatively estimated based on plausibility and/or compatibility with known results, such as reservoir volume.
The Inputs and Results tables below highlight key input assumptions (for parameters lacking publicly available data) and 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.)
| Parameter | Input Value(s) | Source |
|---|---|---|
| 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 | Maximum flow rate achieved at Cape Station per https://www.businesswire.com/news/home/20240910997008/en/Fervo-Energys-Record-Breaking-Production-Results-Showcase-Rapid-Scale-Up-of-Enhanced-Geothermal. The announced increased casing diameter implies higher flow rates. |
| Number of doublets | 54 | Estimate based on extrapolation from Project Red and Fervo_Project_Cape-3 |
| Reservoir size & geometry | Reservoir Volume = 5,801,599,999 m³; Fracture Separation = 10 m | Extrapolation to based on a resulting heat extraction profile that is plausible and compatible with required electricity production. Actual number and size of fractures not known. |
| Water Loss Rate | 15% | Water loss rate estimated to be between 10 and 20% |
| Maximum Drawdown | 0.009 | Tuned to keep minimum net electricity generation ≥ 500 MWe and number of times redrilling = 1 |
| Reservoir Impedance | 0.001 GPa.s/m³ | Same as 400 MWe case study (Fervo_Project_Cape-3) |
| 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 https://atb.nrel.gov/electricity/2024/geothermal. 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, 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; Latimer, T. (2025, February 12). Catching up with enhanced geothermal (D. Roberts, Interviewer). https://www.volts.wtf/p/catching-up-with-enhanced-geothermal. |
| Reservoir Stimulation Capital Cost Adjustment Factor | 2 | Estimated cost of ~$1.5M per well falls within typical range of $0.5–2M |
| Capital Cost for Power Plant for Electricity Generation | $1900/kW | https://betterbuildingssolutioncenter.energy.gov/sites/default/files/attachments/Waste_Heat_to_Power_Fact_Sheet.pdf |
| Discount Rate | 7.5% | Intended to be approximately equivalent to the 8% inflated equity interest rate used in the 400 MWe BICYCLE case study (Fervo_Project_Cape-3) |
| Inflated Bond Interest Rate (debt annual interest rate) | 5.6% | |
| Fraction of Investment in Bonds (percent debt vs. equity) | 28.6% | It is estimated that Fervo currently has more equity financing than debt financing. This particular value is tuned in conjunction with discount rate and interest rate to create a WACC of 8.3% per https://www.linkedin.com/pulse/fervo-energy-technology-day-2024-entering-geothermal-decade-matson-n4stc. 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) |
See tests/examples/Fervo_Project_Cape-4.txt in source code for the full set of inputs.
| Metric | Result Value(s) | Reference Value | Reference Source |
|---|---|---|---|
| LCOE | $73/MWh | $80/MWh | https://www.nature.com/articles/s44359-024-00019-9 |
| Project capital costs | ~$4200/kW (based on maximum total electricity generation) | $4500/kW, $3000–$6000/kW | https://www.nature.com/articles/s44359-024-00019-9; Latimer, T. (2025, February 12). Catching up with enhanced geothermal (D. Roberts, Interviewer). https://www.volts.wtf/p/catching-up-with-enhanced-geothermal. |
| Maximum Total Electricity Generation | 564 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 550 MW. | |
| Minimum Net Electricity Generation | 505 MW | 500 MW | https://fervoenergy.com/fervo-energy-announces-31-mw-power-purchase-agreement-with-shell-energy/. The 500 MW PPA is interpreted to mean that Cape Station's net electricity generation must never fall below 500 MWe. |
| Average Production Temperature | 200℃ | 204℃, 190.6–198.6℃ (optimal plant operating range) | https://jpt.spe.org/fervo-and-forge-report-breakthrough-test-results-signaling-more-progress-for-enhanced-geothermal; https://eartharxiv.org/repository/view/7665/. |
| Well Drilling and Completion Cost Correlation | $3.96M/well | $<4M/well | Latimer, T. (2025, February 12). Catching up with enhanced geothermal (D. Roberts, Interviewer). https://www.volts.wtf/p/catching-up-with-enhanced-geothermal |
| WACC | 8.3% | 8.3% | https://www.linkedin.com/pulse/fervo-energy-technology-day-2024-entering-geothermal-decade-matson-n4stc |
| After-tax IRR | 18.80% | 15–25% | Typical levered returns for energy projects |
| Number of times redrilling | 1 | 1–2 | Redrilling expected to be required within 5–10 years of project start |
See tests/examples/Fervo_Project_Cape-4.out in source code for the results.