An internal carbon price is a straightforward idea that gets complicated in practice. You assign a dollar-per-tCO2e value to your organization's emissions, then use that price to shadow-cost capital projects, procurement decisions, and operational changes. The point is to make carbon a factor in financial decision-making before external regulation forces it to be.
The problem most sustainability managers hit: the finance team won't engage with a carbon price that doesn't connect to real numbers. An arbitrary $50/tCO2e number — chosen because it felt reasonable or because a peer company mentioned it — generates the response "why $50 and not $10?" The conversation stalls, and the internal carbon price becomes a sustainability team exercise rather than a financial planning tool.
This post describes how to build a carbon price that finance teams find credible, starting from the emission data you should already have.
Two types of internal carbon price, and they serve different purposes
Before getting into methodology, it's worth distinguishing between the two main approaches to internal carbon pricing, because they're designed to do different things.
A shadow price (also called an implicit carbon price) is used in capital project evaluation. When comparing a standard piece of equipment against a more efficient alternative, the shadow price converts the emissions difference into a dollar cost difference, allowing apples-to-apples financial comparison. The shadow price doesn't change current costs — it's a forward-looking planning tool that makes emission reduction investments look more attractive by incorporating anticipated future carbon costs.
An internal fee or tax charges business units or facilities based on their actual emissions, with funds pooled centrally and then allocated to emission reduction projects or returned to business units that exceed targets. This is a stronger intervention — it changes current incentives and requires actual financial transfers within the organization. It also requires more organizational buy-in to implement.
Most manufacturing companies starting with internal carbon pricing begin with the shadow price approach, because it's less disruptive and easier to validate.
What price level is defensible
The most credible approach to setting an internal carbon price ties it to external reference points your finance team can verify independently. Three reference points are commonly used in combination:
Regulatory floor: If your company has any operations in jurisdictions with active carbon pricing — EU ETS, California cap-and-trade, RGGI — the market price in those systems represents the minimum cost your company would face if carbon pricing extended to your jurisdiction. As of early 2025, EU ETS allowances have traded in the €50-€75/t range. California's cap-and-trade allowance price has run roughly $30-$40/short ton. These are real market prices, not theoretical constructs.
Social cost of carbon: The US Interagency Working Group on the Social Cost of Carbon publishes estimates of the economic damage from emitting one additional ton of CO2, used in federal regulatory analysis. The 2023 revised estimate is approximately $190/tCO2 at a 3% discount rate. Finance teams sometimes resist this figure as politically constructed, which is a fair methodological critique — but it establishes a ceiling that helps anchor the range.
Abatement cost benchmarks: The most operationally grounded reference is the marginal abatement cost specific to your operations — what does it actually cost to reduce one tCO2e using available decarbonization options at your facilities? This requires knowing your emission inventory at the facility level, which is why a functioning GHG accounting system is a prerequisite to a credible internal carbon price.
A defensible starting range for a Michigan-based manufacturer in 2025, based on these references, is roughly $40-$80/tCO2e for shadow pricing purposes. Below $40 understates the direction of regulatory trajectory. Above $80 tends to make projects look financially unfavorable in ways that aren't yet realized costs.
The emission inventory prerequisite
Here's the dependency chain that often gets missed: an internal carbon price only does useful work if you have emission volumes to multiply it by. If your Scope 1 and Scope 2 figures are rough estimates, and your Scope 3 is essentially unknown, then applying a $50/tCO2e shadow price to a capital project produces a number that's as uncertain as the underlying emission estimate.
Finance teams are acute at spotting this. If the shadow carbon cost on a project is $200,000 based on an emission estimate with a ±40% uncertainty band, the $200,000 figure carries that same uncertainty. A CFO who understands this will discount the carbon cost appropriately — perhaps to the point of not weighting it in the decision at all.
The practical implication: building an internal carbon price before building a solid emission inventory is backwards. The emission inventory is the foundation. The carbon price is the analytical layer on top of it.
Scope 1 and Scope 2 should be calculable to relatively tight uncertainty (±5-15% for well-managed operations) from utility invoices and fuel delivery records. Scope 3 will have wider uncertainty ranges, particularly for Category 1 purchased goods — but even spend-based estimates with documented methodology give you something to price.
How to structure the shadow price in capital approvals
Once you have a carbon price and an emission inventory, here's the mechanics of incorporating it into capital approvals:
For each capital project, estimate the incremental annual emission impact — positive (increase) or negative (decrease) in tCO2e per year. Multiply by the shadow price to get the annual carbon cost or saving. Discount the stream over the project life at your WACC or hurdle rate. Add that discounted carbon value to the project NPV calculation.
A concrete example: a manufacturing facility is evaluating replacing natural gas-fired process heating with electric resistance heating. The equipment costs $180,000 more than a direct gas replacement. Annual natural gas savings are 2,400 MMBtu, which at 53.06 kg CO2 per MMBtu converts to roughly 127 tCO2e per year of Scope 1 reduction. At a shadow price of $55/tCO2e, that's $7,000/year of shadow carbon saving. Over 10 years at an 8% discount rate, the discounted shadow value is approximately $47,000 — meaningfully closing the gap on the $180,000 premium.
That $47,000 doesn't show up in your P&L today. But it represents real economic exposure if carbon pricing expands, and real avoided compliance cost if it does. Finance teams can engage with that framing once the numbers are connected to a specific, auditable emission calculation — not an estimate pulled from a benchmark study.
The organizational mechanics: who owns the price, who applies it
For a shadow price approach, the mechanics are relatively clean: the sustainability team proposes the price and update cadence (annually is typical), the CFO or finance committee approves it, and the approved price is built into the capital project template. Business units apply it automatically when they submit capital requests that have significant emission implications.
The question that often comes up: should it be voluntary (business units may apply it) or mandatory (all projects above a certain size must include a carbon shadow cost)? Mandatory produces better decision data — you don't get selection effects from business units choosing not to apply the price to projects where it would change the outcome. We'd suggest mandatory for any project with an estimated lifetime emission impact above some threshold you define, say 500 tCO2e cumulative.
What we're not saying
We're not saying that an internal carbon price will immediately change project outcomes across your organization. At $50-$80/tCO2e, the shadow cost is meaningful for large-scale energy projects but relatively small compared to core equipment and labor costs for most manufacturing investments. The near-term impact is at the margin — tipping borderline projects toward the emission-efficient option rather than overriding conventional financial analysis.
We're also not saying that implementing an internal carbon price is sufficient preparation for external carbon regulation. If EU ETS ever expands to cover imported goods in ways that directly affect your products, or if US federal carbon pricing advances, the actual compliance costs will be determined by your real emission levels — which requires the same solid inventory work discussed above, regardless of what internal price you've been using.
The value of the internal price is the decision hygiene it creates: projects and procurement choices are evaluated with carbon costs included, building organizational muscle memory around emission-conscious capital allocation before external requirements make it mandatory. That's worth doing now, and doing it credibly requires the emission data infrastructure to back it up.