CAPEX/OPEX Screening

Use this skill for a quick, public screening of project cost. Given a bare equipment cost, it applies a public installation (Lang/Hand-style) factor and a contingency allowance to estimate a total installed CAPEX, then adds a simple OPEX (a fraction of CAPEX per year plus an annual energy cost) to produce a lifecycle total cost of ownership. It is intentionally simple and should guide users toward the validated NeqSim CostEstimationCalculator (Turton / Peters / Ulrich / Seider correlations with CEPCI escalation) and the NeqSim MCP runFieldEconomics workflow for real estimates.

When to Use

• When a user wants a first-pass CAPEX and OPEX magnitude for a concept.
• When an agent needs a cost feed for an asset-value / NPV screening chain.
• When examples must run without confidential cost data or licensed estimating tools.

Inputs

• bare_equipment_cost_musd: total bare (uninstalled) equipment cost in million USD.
• installation_factor: Lang/Hand-style multiplier from bare to installed cost (default 3.5).
• contingency_fraction: contingency added on top of installed cost (default 0.2).
• opex_fraction_of_capex_per_year: annual OPEX as a fraction of total CAPEX (default 0.04).
• annual_energy_use_mwh: optional annual energy use for the energy-cost term (default 0).
• energy_price_usd_per_mwh: optional energy price (default 0).
• project_life_years: number of years used for the lifecycle OPEX roll-up (default 20).

Outputs

• installed_capex_musd: bare cost * installation factor.
• total_capex_musd: installed CAPEX including contingency.
• annual_opex_musd: OPEX-fraction term per year.
• annual_energy_cost_musd: energy-cost term per year.
• total_annual_opex_musd: sum of the two OPEX terms.
• lifecycle_opex_musd: total annual OPEX times project life.
• total_cost_of_ownership_musd: total CAPEX plus lifecycle OPEX.
• capex_warning: ok, watch, or high (magnitude flag vs a configurable threshold).
• neqsim_available: whether the optional NeqSim package is importable.
• assumptions: public assumptions and required follow-up.

Engineering Method

The factored estimate uses the classic installation-factor approach: CAPEX_installed = C_equipment * f_install, then CAPEX_total = CAPEX_installed * (1 + contingency). Annual OPEX is opex_fraction * CAPEX_total + (energy_use_MWh * energy_price_USD/MWh). The lifecycle roll-up multiplies the total annual OPEX by the project life, and the total cost of ownership adds CAPEX and lifecycle OPEX. The verdict is a simple magnitude flag against a configurable CAPEX threshold.

This skill applies no CEPCI escalation, material or pressure factors, location factor, currency conversion, phasing, financing, depreciation, or abandonment cost. It is a transparent placeholder that must be replaced by a validated NeqSim cost estimate for any quantitative use.

Python Usage Pattern

from capex_opex_screening import CapexOpexModel

model = CapexOpexModel()
result = model.evaluate(
    bare_equipment_cost_musd=120.0,
    installation_factor=3.5,
    contingency_fraction=0.25,
    opex_fraction_of_capex_per_year=0.04,
    annual_energy_use_mwh=180000.0,
    energy_price_usd_per_mwh=60.0,
    project_life_years=20,
)

print(result.total_capex_musd)
print(result.total_annual_opex_musd)
print(result.total_cost_of_ownership_musd)
print(result.capex_warning)

Validated NeqSim Path

This screening is a placeholder. For real cost estimates use:

• NeqSim CostEstimationCalculator — equipment-level CAPEX with Turton / Peters / Ulrich / Seider correlations, CEPCI escalation, material/pressure factors, and AACE class 1–5 (see the neqsim-equipment-cost-estimation skill).
• The field-development DCF utilities in neqsim.process.util.fielddevelopment for CAPEX/OPEX phasing and cash-flow modelling (see neqsim-field-economics).
• The NeqSim MCP runFieldEconomics tool for an orchestrated economics evaluation.

Escalation

Escalate any watch or high verdict, and any quantitative use, to a validated NeqSim cost estimate and qualified cost-engineering review.

Validation Checklist

• Inputs are validated and within stated ranges.
• Examples use public data only.
• Screening assumptions are stated explicitly.
• Limitations are respected.
• Quantitative use is escalated to validated NeqSim models.

Common Mistakes

Limitations

• Educational screening only; not a validated design method.
• No confidential data or proprietary methods are included.
• Escalate any quantitative or design use to validated NeqSim workflows.

References

• NeqSim repository: https://github.com/equinor/neqsim
• NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md