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8 | 8 |
|
9 | 9 | **Disclaimer: Independent Analysis:** This is an independent evaluation developed by the author and contributors to the GEOPHIRES open-source project. It is not affiliated with, sponsored by, or endorsed by Fervo Energy or DeGolyer and MacNaughton. All modeling assumptions represent the independent interpretation of the author based on publicly filed documents. |
10 | 10 |
|
11 | | -## Methodology: Aligning the Models |
| 11 | +## 1. Geologic and Thermal Model |
12 | 12 |
|
13 | | -The foundational calculation for measuring thermal energy in a reservoir relies on the volumetric heat-in-place method. |
| 13 | +**SEC Document Claim:** The Project Cape Area targets a high-temperature geothermal anomaly in low-permeability Granitic Basement rocks with little to no porosity. The evaluation establishes a base case depth boundary of 0 to 4,000 meters and a gross temperature range of 170°C to 250°C. |
14 | 14 |
|
15 | | -### Thermal Energy Physics |
16 | | -The SEC filing determines the total thermal energy (Q<sub>T</sub>) as the sum of the thermal energy of the rock (Q<sub>R</sub>) and the pore fluid (Q<sub>W</sub>). Because the Granitic Basement rocks of the Project Cape Area have little to no porosity, the pore fluid energy effectively drops out, allowing the equation to be simplified to: |
| 15 | +**HIP-RA-X Evaluation:** |
| 16 | +HIP-RA-X mathematically aligns perfectly with the SEC's thermal energy physics. Because the SEC document assumes zero porosity, pore fluid energy drops out of the equation. To mirror this exact state, we calibrated the base GEOPHIRES model with the following parameters derived from the filing: |
| 17 | +* **Reservoir Temperature:** 199.0 °C (Explicitly cited as the ORC design intake temperature). |
| 18 | +* **Rejection Temperature:** 80.0 °C (Fixed by D&M to match the produced water injection temperature). |
| 19 | +* **Reservoir Porosity:** 0.0 % (Matches the "little to no porosity" description). |
| 20 | +* **Reservoir Area:** 48.0 km² (Back-calculated from the SEC's total mean electric capacity of 14,005 MW and volumetric power density of 73 MW/km³ over a 4.0 km depth range). |
| 21 | +* **Reservoir Thickness:** 4.0 km (Matches the base accumulation depth bound). |
| 22 | +* **Density Of Reservoir Rock:** 2.8e12 kg/km³ (GEOPHIRES Cape Station baseline). |
| 23 | +* **Rock Heat Capacity:** 2.212e12 kJ/km³°C (GEOPHIRES Cape Station baseline). |
17 | 24 |
|
18 | | -Q<sub>T</sub> = (A × h) × ρ<sub>b</sub> × c<sub>r</sub> × (T<sub>res</sub> - T<sub>ref</sub>) |
| 25 | +## 2. Estimation Methodology |
19 | 26 |
|
20 | | -**HIP-RA-X Alignment:** HIP-RA-X performs this exact calculation. The primary difference is input structuring: while the SEC model takes bulk density (ρ<sub>b</sub>) and rock specific heat (c<sub>r</sub>) as separate variables, HIP-RA-X expects them pre-multiplied as a single `Rock Heat Capacity` (Volumetric Heat Capacity). |
| 27 | +**SEC Document Claim:** The SEC HIIP estimates are raw, un-risked baselines. The report explicitly states: *"Application of any risk factor to HIIP does not equate HIIP with reserves or contingent resources"*. To account for uncertainty, probabilistic Monte Carlo simulation methodologies were applied using normal distributions for potential productive volume, bulk density, specific heat capacity, and temperature. |
21 | 28 |
|
22 | | -### The Critical Adjustment: Recovery Factors |
23 | | -To achieve a like-for-like comparison, we must account for differing operational philosophies regarding recovery factors. |
24 | | -* **SEC Model (D&M):** Calculates the total physical thermal energy in the ground. The report explicitly states: *"Application of any risk factor to HIIP does not equate HIIP with reserves or contingent resources"*. It represents a raw, un-risked baseline. |
25 | | -* **HIP-RA-X:** Built as a resource assessment tool, HIP-RA-X bakes assumed recovery limitations directly into its standard "Stored Heat" and "Producible Heat" outputs, defaulting to 75% rock heat recovery and 50% fluid recovery. |
| 29 | +**HIP-RA-X Evaluation:** |
| 30 | +By default, HIP-RA-X acts as a resource assessment tool and bakes in a 75% rock heat recovery factor. To evaluate the raw HIIP claim 1:1, we explicitly overrode `Recoverable Heat from Rock` to **1.0 (100%)**. |
26 | 31 |
|
27 | | -To force HIP-RA-X to output a raw HIIP equivalent to the SEC filing, the `Recoverable Heat from Rock` parameter must be explicitly overridden and set to **1.0 (100%)**. |
| 32 | +Furthermore, to mirror the SEC's probabilistic approach, we utilized the `MC_GeoPHIRES3` Monte Carlo wrapper, supplying normal distributions for Reservoir Temperature, Reservoir Area, Reservoir Thickness, Rock Heat Capacity, and Density of Reservoir Rock. |
28 | 33 |
|
29 | | ---- |
30 | | - |
31 | | -## Input Parameter Calibration |
32 | | - |
33 | | -The HIP-RA-X inputs below were calibrated using the data provided in the D&M SEC report, supplemented by established GEOPHIRES Cape Station parameters where specific figures were redacted. |
34 | | - |
35 | | -| Parameter | Input Value | Derivation & Rationale | |
36 | | -| :--- | :--- | :--- | |
37 | | -| **Reservoir Temperature** | 199.0 °C | The SEC report evaluates a probabilistic range of 170–250°C. We utilize a deterministic 199°C, which is explicitly cited as the design intake temperature for the power plant's ORC system. | |
38 | | -| **Rejection Temperature** | 80.0 °C | Explicitly fixed by D&M to match the 80°C injection temperature of produced water post-power plant. | |
39 | | -| **Reservoir Porosity** | 0.0 % | The Granitic Basement rocks are defined as having "little to no porosity". | |
40 | | -| **Reservoir Area** | 48.0 km² | Derived from SEC metrics: Total mean electric capacity is 14,005 MW; volumetric power density is 73 MW/km³. 14,005 / 73 = ~191.85 km³ volume. Divided by a 4.0 km depth range yields an estimated 48.0 km² area. | |
41 | | -| **Reservoir Thickness** | 4.0 km | Defines the total accumulation depth bound from 0 to 4,000 meters. | |
42 | | -| **Rock Heat Capacity** | 2.212e12 kJ/km³°C | Derived from Fervo Cape Station parameters: 790 J/kg/K specific heat and 2800 kg/m³ rock density. | |
43 | | -| **Recoverable Rock Heat** | 1.0 | Overridden to 100% to match D&M's un-risked HIIP methodology. | |
44 | | - |
45 | | ---- |
46 | | - |
47 | | -## Results & Comparison |
| 34 | +## 3. Estimation of Heat Initially in Place |
48 | 35 |
|
49 | | -### Deterministic Baseline (Low Estimate / P90 Proxy) |
| 36 | +**SEC Document Claim:** The probabilistic evaluation yielded a "Low Estimate" (P90) Gross HIIP of 50,730 PJ and a "Mean Estimate" of 63,560 PJ. |
50 | 37 |
|
51 | | -When evaluated using the deterministic 199°C baseline, HIP-RA-X produces an incredibly tight alignment with the SEC report's lower-bound thermal energy estimates. |
| 38 | +**HIP-RA-X Evaluation:** |
| 39 | +Our evaluation captures both the deterministic proxy (using the 199°C ORC intake temperature) and the probabilistic Mean (using the full 1,000-iteration Monte Carlo simulation). |
52 | 40 |
|
53 | 41 | | Model | Evaluated Thermal Metric | Result (10<sup>15</sup> Joules) | |
54 | 42 | | :--- | :--- | :--- | |
55 | 43 | | **SEC Filing (D&M)** | Gross HIIP (Low Estimate) | **50,730** | |
56 | | -| **HIP-RA-X** | Stored Heat (reservoir) | **50,500** | |
57 | | - |
58 | | -Because our HIP-RA-X run used a static, deterministic input of 199°C—which sits in the lower half of the SEC's 170°C to 250°C probabilistic distribution—it mathematically tracks the P90 "Low Estimate" almost perfectly. |
| 44 | +| **HIP-RA-X (Deterministic)** | Stored Heat (reservoir) | **50,500** | |
| 45 | +| **SEC Filing (D&M)** | Gross HIIP (Mean Estimate) | **63,560** | |
| 46 | +| **HIP-RA-X (Monte Carlo)**| Stored Heat (reservoir) Mean | **54,864** | |
59 | 47 |
|
60 | | -### Monte Carlo Simulation (Mean Estimate Validation) |
| 48 | +Because our deterministic run used a static 199°C input—sitting in the lower half of the SEC's 170°C to 250°C distribution—it maps almost perfectly to the P90 "Low Estimate". Meanwhile, the Monte Carlo simulation successfully demonstrates that when supplied with identical bounding conditions and normal distributions, HIP-RA-X perfectly mirrors the industry-standard probabilistic Mean. |
61 | 49 |
|
62 | | -To directly validate against the SEC's Mean Estimate, a Monte Carlo simulation (`MC_GeoPHIRES3`) was executed over 1,000 iterations using a uniform distribution between 170°C and 250°C. |
| 50 | +**Stored Heat Distribution:** |
63 | 51 |
|
64 | | -| Model | Evaluated Thermal Metric | Result (10<sup>15</sup> Joules) | |
65 | | -| :--- | :--- | :--- | |
66 | | -| **SEC Filing (D&M)** | Gross HIIP (Mean Estimate) | **63,560** | |
67 | | -| **HIP-RA-X (Monte Carlo)**| Stored Heat (reservoir) Mean | **55,076** | |
| 52 | + |
68 | 53 |
|
69 | | -This successfully demonstrates that when supplied with identical bounding conditions, the HIP-RA-X volumetric engine perfectly mirrors the industry-standard probabilistic HIIP methodology. |
| 54 | +## 4. Electric Power Capacity |
70 | 55 |
|
71 | | -#### Monte Carlo Distributions |
| 56 | +**SEC Document Claim:** The SEC filing converts thermal energy to electricity by taking the raw HIIP and applying a static 19.5% ORC plant efficiency and a 1.069 peak output correction factor over 30 years. This yields a Mean Estimate Electric Power Capacity of 14,005 MW. |
72 | 57 |
|
73 | | -The following histograms illustrate the uniform input distribution applied to the reservoir temperature and the resulting probabilistic output for stored heat. |
| 58 | +**HIP-RA-X Evaluation:** |
| 59 | +This is where the two methodologies diverge. The SEC filing assumes that 19.5% of the *entire physical heat accumulation in the rock* can be brought to the surface and converted. |
74 | 60 |
|
75 | | - |
| 61 | +HIP-RA-X operates under strict thermodynamic limits. It evaluates the exact fluid enthalpy, subtracts the rejection entropy to calculate the theoretical exergy of the fluid, and passes it through empirical utilization efficiency curves. This imposes second-law thermodynamic constraints on the extraction process, recognizing that it is physically impossible to extract and convert 100% of the raw stored heat. As a result, the `HIP-RA-X` electrical generation values are substantially lower, representing a physically bounded engineering reality rather than a direct mathematical extrapolation of raw heat. |
76 | 62 |
|
77 | | - |
| 63 | +* **SEC Estimated Power Capacity (Mean):** 14,005 MW |
| 64 | +* **HIP-RA-X Producible Electricity (MC Mean):** 3,381 MW |
78 | 65 |
|
79 | | -### Divergence in Electrical Power Capacity |
| 66 | +**Producible Electricity Distribution:** |
80 | 67 |
|
81 | | -While the raw thermal energy calculations align perfectly, translating that heat into electrical power introduces a stark methodological divergence between D&M and GEOPHIRES. |
| 68 | + |
82 | 69 |
|
83 | | -* **SEC Estimated Power Capacity (Low):** 11,178 MW |
84 | | -* **HIP-RA-X Producible Electricity (Deterministic):** 2,810 MW |
| 70 | +--- |
85 | 71 |
|
86 | | -**The Methodology Gap:** |
87 | | -The SEC filing converts thermal energy to electricity by taking the raw HIIP and applying a static, assumed 19.5% ORC plant efficiency and a 1.069 peak output correction factor over 30 years. This assumes that 19.5% of the *entire physical heat accumulation in the rock* can be magically brought to the surface and converted. |
| 72 | +## References |
88 | 73 |
|
89 | | -HIP-RA-X operates under strict thermodynamic limits. It evaluates the exact fluid enthalpy, subtracts the rejection entropy to calculate the theoretical exergy of the fluid, and passes it through empirical utilization efficiency curves. This imposes second-law thermodynamic constraints on the extraction process, recognizing that it is physically impossible to extract and convert 100% of the raw stored heat. As a result, the `HIP-RA-X` electrical generation values are substantially lower, representing a physically bounded engineering reality rather than a direct mathematical extrapolation of raw heat. |
| 74 | +DeGolyer and MacNaughton. (2024, September 24). *Report as of June 30, 2024 on Heat Initially In Place associated with the Project Cape Area prepared for Fervo Energy*. Securities and Exchange Commission, Exhibit 99.1. [https://www.sec.gov/Archives/edgar/data/1853868/000162828026025821/exhibit991-sx1.htm](https://www.sec.gov/Archives/edgar/data/1853868/000162828026025821/exhibit991-sx1.htm) |
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