From 6c79b128f3bb53b832c4a74ab7d3cd09f9d4f5e2 Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Sun, 1 Feb 2026 10:29:38 -0800 Subject: [PATCH 1/7] WIP - initial draft of Discussion, Limitations, & Future Work section --- docs/Fervo_Project_Cape-5.md.jinja | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index 06eb2bfe..279f9586 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -476,6 +476,28 @@ Key differences: {# TODO others e.g. Fervo_Project_Cape-3... #} +## Discussion, Limitations, & Future Work + +While this case study establishes a validated baseline for Second-of-a-Kind (SOAK) EGS viability using standardized +consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as a "plant-gate" feasibility +capability rather than a fully burdened commercial pro-forma. +Several financial, technical, and regulatory factors were not explicitly modeled and represent areas for future refinement. + +### Financial & Corporate Structure Limitations + +The current economic model (SAM Single Owner PPA) focuses on project-level cash flows but excludes several +"soft cost" realities of non-recourse project financing. +Including these would likely reduce the levered IRR by several percentage points: + +1. Working Capital & Reserves: The cash flow analysis assumes immediate liquidity. It does not model Debt Service Reserve Accounts (DSRA) or Major Maintenance Reserve Accounts (MMRA), which typically require "locking up" 6 months of debt service or significant cash balances, creating a cash drag on equity returns. +1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may range from 1–3% of the total debt volume, representing a sunk cost at Financial Close (FID) that is not reflected here. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant tracking issue on GitHub. +1. Insurance Premiums: The model does not include specific line items for Construction All-Risk (CAR) or Operation All-Risk (OAR) insurance. For EGS projects involving deep subsurface risks, insurance premiums could represent an additional annual operating expense not captured in the standard "percentage of CAPEX" OPEX methodology. + +### Technical & Operational Considerations + +1. Grid Interconnection & Transmission: For a 500 MWe project, interconnection costs (substation upgrades, gen-tie lines) can be substantial. Unless the site is adjacent to high-capacity transmission with available queue space, interconnection costs could add materially to the project budget. +1. Seasonal and Hourly Performance Granularity: As noted in the Surface Plant Parameters, this study uses a fixed annual average ambient temperature. It does not model the seasonal or hourly impacts on air-cooled condenser efficiency. In reality, power output would likely dip during peak summer hours and increase during winter. Future versions of GEOPHIRES may add support for these considerations; [click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/395) to view the relevant tracking issue on GitHub. + --- ## References From ae2e04a0c75e6ee41c6ad70a7fad72f2eda52b31 Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 09:34:42 -0800 Subject: [PATCH 2/7] Clarify Total Capital Cost is OCC for SAM-EM in tooltip text --- src/geophires_x/Economics.py | 3 ++- src/geophires_x_schema_generator/geophires-request.json | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/src/geophires_x/Economics.py b/src/geophires_x/Economics.py index 762d3ea4..3780133a 100644 --- a/src/geophires_x/Economics.py +++ b/src/geophires_x/Economics.py @@ -920,7 +920,8 @@ def __init__(self, model: Model): Valid=False, ErrMessage="calculate total capital cost using user-provided costs or" + " built-in correlations for each category.", - ToolTipText="Total initial capital cost." + ToolTipText=f'Total initial capital cost. For SAM Economic Models, ' + f'this is treated as the {overnight_capital_cost_output_parameter().Name}.' ) self.oamtotalfixed = self.ParameterDict[self.oamtotalfixed.Name] = floatParameter( "Total O&M Cost", diff --git a/src/geophires_x_schema_generator/geophires-request.json b/src/geophires_x_schema_generator/geophires-request.json index 224b8252..932f3548 100644 --- a/src/geophires_x_schema_generator/geophires-request.json +++ b/src/geophires_x_schema_generator/geophires-request.json @@ -1639,7 +1639,7 @@ "maximum": 10 }, "Total Capital Cost": { - "description": "Total initial capital cost.", + "description": "Total initial capital cost. For SAM Economic Models, this is treated as the Overnight Capital Cost.", "type": "number", "units": "MUSD", "category": "Economics", From d2ad2a212c68ed716d80b5388e044399b31c2276 Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 09:44:09 -0800 Subject: [PATCH 3/7] discussion section iteration (still WIP) --- docs/Fervo_Project_Cape-5.md.jinja | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index 279f9586..9416088a 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -479,24 +479,29 @@ Key differences: ## Discussion, Limitations, & Future Work While this case study establishes a validated baseline for Second-of-a-Kind (SOAK) EGS viability using standardized -consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as a "plant-gate" feasibility +consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as a "plant-gate" feasibility {# WIP - phrasing #} capability rather than a fully burdened commercial pro-forma. Several financial, technical, and regulatory factors were not explicitly modeled and represent areas for future refinement. -### Financial & Corporate Structure Limitations +Users may wish to explicitly encode these cost factors in their own models by using applicable adjustment parameters. +For OPEX, such parameters may include `Wellfield O&M Cost Adjustment Factor`, +`Surface Plant O&M Cost Adjustment Factor` or `Total O&M Cost`. For CAPEX, `One-time Flat License Fees Etc` or +`Total Capital Cost` may be appropriate. -The current economic model (SAM Single Owner PPA) focuses on project-level cash flows but excludes several -"soft cost" realities of non-recourse project financing. -Including these would likely reduce the levered IRR by several percentage points: +### Financial Considerations -1. Working Capital & Reserves: The cash flow analysis assumes immediate liquidity. It does not model Debt Service Reserve Accounts (DSRA) or Major Maintenance Reserve Accounts (MMRA), which typically require "locking up" 6 months of debt service or significant cash balances, creating a cash drag on equity returns. -1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may range from 1–3% of the total debt volume, representing a sunk cost at Financial Close (FID) that is not reflected here. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant tracking issue on GitHub. -1. Insurance Premiums: The model does not include specific line items for Construction All-Risk (CAR) or Operation All-Risk (OAR) insurance. For EGS projects involving deep subsurface risks, insurance premiums could represent an additional annual operating expense not captured in the standard "percentage of CAPEX" OPEX methodology. +The case study economic results focus on project-level cash flows but do not explicitly include several "soft cost" +realities of non-recourse project financing. +Including these may reduce the levered IRR by several percentage points. + +1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may constitute a small percent of total debt volume. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant GEOPHIRES tracking issue on GitHub. +1. Reserve Accounts: The cash flow analysis assumes immediate liquidity. It does not model working capital, debt service, or reserve accounts, or major equipment replacement reserve accounts. Project financial partners may require that the project owner(s) establish and fund reserve accounts. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/460) to view the relevant GEOPHIRES tracking issue on GitHub. +1. Insurance Premiums: The model does not include a specific line item for insurance. For EGS projects involving deep subsurface risks, insurance premiums could represent an additional annual operating expense. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/369) to view the relevant GEOPHIRES tracking issue on GitHub. ### Technical & Operational Considerations 1. Grid Interconnection & Transmission: For a 500 MWe project, interconnection costs (substation upgrades, gen-tie lines) can be substantial. Unless the site is adjacent to high-capacity transmission with available queue space, interconnection costs could add materially to the project budget. -1. Seasonal and Hourly Performance Granularity: As noted in the Surface Plant Parameters, this study uses a fixed annual average ambient temperature. It does not model the seasonal or hourly impacts on air-cooled condenser efficiency. In reality, power output would likely dip during peak summer hours and increase during winter. Future versions of GEOPHIRES may add support for these considerations; [click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/395) to view the relevant tracking issue on GitHub. +1. Seasonal and Hourly Performance Granularity: As noted in the Surface Plant Parameters, this study uses a fixed annual average ambient temperature. It does not model the seasonal or hourly impacts on air-cooled condenser efficiency. In reality, power output would likely dip during peak summer hours and increase during winter. Future versions of GEOPHIRES may add support for these considerations; [click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/395) to view the relevant GEOPHIRES tracking issue on GitHub. --- From 2b5a635118a2b3f41eec725bd9d0938576693acd Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 09:49:18 -0800 Subject: [PATCH 4/7] improve discussion section phrasing --- docs/Fervo_Project_Cape-5.md.jinja | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index 9416088a..6fc9b9dc 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -479,8 +479,8 @@ Key differences: ## Discussion, Limitations, & Future Work While this case study establishes a validated baseline for Second-of-a-Kind (SOAK) EGS viability using standardized -consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as a "plant-gate" feasibility {# WIP - phrasing #} -capability rather than a fully burdened commercial pro-forma. +consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as an assessment of intrinsic project +viability rather than a fully burdened commercial pro-forma. Several financial, technical, and regulatory factors were not explicitly modeled and represent areas for future refinement. Users may wish to explicitly encode these cost factors in their own models by using applicable adjustment parameters. @@ -490,8 +490,8 @@ For OPEX, such parameters may include `Wellfield O&M Cost Adjustment Factor`, ### Financial Considerations -The case study economic results focus on project-level cash flows but do not explicitly include several "soft cost" -realities of non-recourse project financing. +The case study economic results focus on project-level cash flows but do not explicitly include several overhead costs +and administrative realities often associated with commercial project financing. Including these may reduce the levered IRR by several percentage points. 1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may constitute a small percent of total debt volume. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant GEOPHIRES tracking issue on GitHub. From d29ea3f358cfbf8b9a83c91761b74a8a6b66bafa Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 10:34:56 -0800 Subject: [PATCH 5/7] redrilling and reservoir modelling limitations/future work --- docs/Fervo_Project_Cape-5.md.jinja | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index 6fc9b9dc..f9a10663 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -478,10 +478,10 @@ Key differences: ## Discussion, Limitations, & Future Work -While this case study establishes a validated baseline for Second-of-a-Kind (SOAK) EGS viability using standardized -consensus data, users should interpret the economic results (LCOE, IRR, NPV, etc.) as an assessment of intrinsic project +While this case study establishes a validated economic baseline for Second-of-a-Kind (SOAK) EGS using standardized +consensus data, users should interpret results (LCOE, IRR, NPV, etc.) as an assessment of intrinsic project viability rather than a fully burdened commercial pro-forma. -Several financial, technical, and regulatory factors were not explicitly modeled and represent areas for future refinement. +Several financial, technical, and operational factors were not explicitly modeled and represent areas for future refinement. Users may wish to explicitly encode these cost factors in their own models by using applicable adjustment parameters. For OPEX, such parameters may include `Wellfield O&M Cost Adjustment Factor`, @@ -490,9 +490,9 @@ For OPEX, such parameters may include `Wellfield O&M Cost Adjustment Factor`, ### Financial Considerations -The case study economic results focus on project-level cash flows but do not explicitly include several overhead costs +The case study economic results focus on project-level cash flows but do not explicitly itemize several overhead costs and administrative realities often associated with commercial project financing. -Including these may reduce the levered IRR by several percentage points. +Including these may reduce the levered IRR. 1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may constitute a small percent of total debt volume. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant GEOPHIRES tracking issue on GitHub. 1. Reserve Accounts: The cash flow analysis assumes immediate liquidity. It does not model working capital, debt service, or reserve accounts, or major equipment replacement reserve accounts. Project financial partners may require that the project owner(s) establish and fund reserve accounts. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/460) to view the relevant GEOPHIRES tracking issue on GitHub. @@ -502,6 +502,8 @@ Including these may reduce the levered IRR by several percentage points. 1. Grid Interconnection & Transmission: For a 500 MWe project, interconnection costs (substation upgrades, gen-tie lines) can be substantial. Unless the site is adjacent to high-capacity transmission with available queue space, interconnection costs could add materially to the project budget. 1. Seasonal and Hourly Performance Granularity: As noted in the Surface Plant Parameters, this study uses a fixed annual average ambient temperature. It does not model the seasonal or hourly impacts on air-cooled condenser efficiency. In reality, power output would likely dip during peak summer hours and increase during winter. Future versions of GEOPHIRES may add support for these considerations; [click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/395) to view the relevant GEOPHIRES tracking issue on GitHub. +1. Redrilling Assumptions: Management of thermal decline is modeled as periodic redrilling events that reset the reservoir's heat content to initial conditions at intervals determined by the `Maximum Drawdown` parameter. The cost of these events is amortized into a uniform annual operating expense. In reality, these events may be scheduled as discrete capital-intensive campaigns punctuated by years of lower spending, or as a continuous program of make-up well drilling to mitigate decline. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/381) to view the relevant GEOPHIRES tracking issue on GitHub. +1. Reservoir Modeling Fidelity: The base case utilizes an analytical model (Gringarten) which assumes uniform flow across idealized fractures. While this approach is computationally efficient for economic scoping, it cannot fully capture complex behaviors like flow channeling (short-circuiting) or fracture heterogeneity. Future work should prioritize integration with physics-based numerical simulators (e.g. TOUGH or ResFrac) to better bound these risks. This case study includes an initial step in this direction via the "ResFrac Profile" variant, which calibrates the production curve to the specific heterogeneous flow behaviors observed in the Singh et al. (2025) study. --- From 2d1c09ae56726c6de3c0a4f47077fae215b93086 Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 10:37:00 -0800 Subject: [PATCH 6/7] fix reserve accounts typo --- docs/Fervo_Project_Cape-5.md.jinja | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index f9a10663..2e940ca9 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -495,7 +495,7 @@ and administrative realities often associated with commercial project financing. Including these may reduce the levered IRR. 1. Transaction & Closing Fees: The Total CAPEX includes interest during construction but does not explicitly budget for debt closing or bank fees. In large-scale energy infrastructure, these transaction costs may constitute a small percent of total debt volume. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/451) to view the relevant GEOPHIRES tracking issue on GitHub. -1. Reserve Accounts: The cash flow analysis assumes immediate liquidity. It does not model working capital, debt service, or reserve accounts, or major equipment replacement reserve accounts. Project financial partners may require that the project owner(s) establish and fund reserve accounts. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/460) to view the relevant GEOPHIRES tracking issue on GitHub. +1. Reserve Accounts: The cash flow analysis assumes immediate liquidity. It does not model working capital, debt service, or major equipment replacement reserve accounts. Project financial partners may require that the project owner(s) establish and fund reserve accounts. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/460) to view the relevant GEOPHIRES tracking issue on GitHub. 1. Insurance Premiums: The model does not include a specific line item for insurance. For EGS projects involving deep subsurface risks, insurance premiums could represent an additional annual operating expense. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/369) to view the relevant GEOPHIRES tracking issue on GitHub. ### Technical & Operational Considerations From 481a71b9bb2499eb5b9d054334796cf15ba21fc2 Mon Sep 17 00:00:00 2001 From: softwareengineerprogrammer <4056124+softwareengineerprogrammer@users.noreply.github.com> Date: Mon, 2 Feb 2026 10:50:06 -0800 Subject: [PATCH 7/7] Reservoir Modeling Fidelity copy edit --- docs/Fervo_Project_Cape-5.md.jinja | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/docs/Fervo_Project_Cape-5.md.jinja b/docs/Fervo_Project_Cape-5.md.jinja index 2e940ca9..c43fe399 100644 --- a/docs/Fervo_Project_Cape-5.md.jinja +++ b/docs/Fervo_Project_Cape-5.md.jinja @@ -503,7 +503,9 @@ Including these may reduce the levered IRR. 1. Grid Interconnection & Transmission: For a 500 MWe project, interconnection costs (substation upgrades, gen-tie lines) can be substantial. Unless the site is adjacent to high-capacity transmission with available queue space, interconnection costs could add materially to the project budget. 1. Seasonal and Hourly Performance Granularity: As noted in the Surface Plant Parameters, this study uses a fixed annual average ambient temperature. It does not model the seasonal or hourly impacts on air-cooled condenser efficiency. In reality, power output would likely dip during peak summer hours and increase during winter. Future versions of GEOPHIRES may add support for these considerations; [click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/395) to view the relevant GEOPHIRES tracking issue on GitHub. 1. Redrilling Assumptions: Management of thermal decline is modeled as periodic redrilling events that reset the reservoir's heat content to initial conditions at intervals determined by the `Maximum Drawdown` parameter. The cost of these events is amortized into a uniform annual operating expense. In reality, these events may be scheduled as discrete capital-intensive campaigns punctuated by years of lower spending, or as a continuous program of make-up well drilling to mitigate decline. [Click here](https://github.com/NatLabRockies/GEOPHIRES-X/issues/381) to view the relevant GEOPHIRES tracking issue on GitHub. -1. Reservoir Modeling Fidelity: The base case utilizes an analytical model (Gringarten) which assumes uniform flow across idealized fractures. While this approach is computationally efficient for economic scoping, it cannot fully capture complex behaviors like flow channeling (short-circuiting) or fracture heterogeneity. Future work should prioritize integration with physics-based numerical simulators (e.g. TOUGH or ResFrac) to better bound these risks. This case study includes an initial step in this direction via the "ResFrac Profile" variant, which calibrates the production curve to the specific heterogeneous flow behaviors observed in the Singh et al. (2025) study. +1. Reservoir Modeling Fidelity: The base case utilizes the Gringarten analytical model, which produces a characteristic thermal plateau maintained until a sharp breakthrough event. A key open question is whether this idealized profile provides an acceptably accurate approximation of drawdown over time, or if it masks the gradual dispersion caused by flow channeling and heterogeneity. Future work should evaluate whether Gringarten remains the optimal scoping proxy, or if an alternative analytical solution[^alt-analytical-solution-proposal] would offer a superior balance of speed and realism by better mimicking the shape of numerical simulation outputs. + +[^alt-analytical-solution-proposal]: Possible alternatives might include Residence Time Distribution (RTD) modeling, or a parameterized profile generator based on the Bezier curve approach used in the "ResFrac Profile" variant. ---