> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mangrovesystems.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Embodied Emissions

> Track and amortize the carbon cost of facilities and equipment across production batches.

Embodied emissions represent the carbon cost of building and installing the physical infrastructure that makes a project possible. Mangrove tracks these emissions in a dedicated system ledger and automatically spreads them across production batches using configurable amortization rules.

## What are embodied emissions?

Carbon removal and renewable fuel projects must account for **all** emissions within their lifecycle boundary, not just the operational ones. Embodied emissions capture the carbon footprint of manufacturing equipment, constructing facilities, and other major capital expenditures that enable a project to operate.

Unlike process emissions (energy consumed during production) or upstream emissions (feedstock transport), embodied emissions are typically **large, one-time costs**. A pyrolysis reactor has a manufacturing footprint. A biochar facility has a construction footprint. These costs need to be fairly distributed across the project's total output rather than assigned to a single batch.

Carbon accounting methodologies typically require projects to include embodied emissions in their lifecycle assessment (LCA). Mangrove's system ledger approach automates this allocation.

<Tip>
  For simple projects, embodied emissions can be modeled as static inputs subtracted directly in the model (see [LCA & Emissions](/accounting-academy/module-3/3-3-lca-and-emissions)). For projects needing balance tracking, automatic amortization, and audit trails, use the system ledger approach described below.
</Tip>

## How it works in Mangrove

Mangrove creates a dedicated **Embodied Emissions ledger** (unit: kgCO₂e) for each project. You add individual embodied emission entries to this ledger, each with a name, total emission amount, and an amortization rule that controls how the cost is spread across batches.

When you generate batches, the production model automatically calculates the amortized deduction for that batch period. The ledger tracks how much has been amortized to date and how much remains.

```mermaid theme={null}
flowchart LR
    EE["Embodied Emission<br/>(total kgCO₂e)"] --> RULE["Amortization<br/>Rule"]
    RULE --> BATCH["Per-Batch<br/>Deduction"]
    BATCH --> NET["Net Carbon<br/>Output"]
    GROSS["Gross Carbon<br/>Removed"] --> NET

    style EE fill:#ffa726,stroke:#f57c00,stroke-width:2px,color:#000
    style RULE fill:#42a5f5,stroke:#1976d2,stroke-width:2px,color:#000
    style BATCH fill:#ffa726,stroke:#f57c00,stroke-width:2px,color:#000
    style GROSS fill:#66bb6a,stroke:#388e3c,stroke-width:2px,color:#000
    style NET fill:#ef5350,stroke:#c62828,stroke-width:2px,color:#000
```

## Amortization rules

Each embodied emission uses one of three amortization rules to determine how the total cost is spread across batches.

### Project Lifetime

Spreads emissions **evenly over time** based on the project's expected lifespan.

The deduction for each batch is proportional to the batch's time range relative to the total project lifetime.

> **Example:** 1,000 kgCO₂e amortized over 10 years. A 30-day batch deducts approximately 8.2 kgCO₂e.

**Best for:** Facility construction, equipment with a known useful life, infrastructure with time-based depreciation.

### Project Production

Spreads emissions **proportionally to actual output**. Batches that produce more carbon removal bear a larger share of the embodied cost.

> **Example:** 1,000 kgCO₂e spread over 50,000 tCO₂e of expected total production. A batch producing 500 tCO₂e deducts 10 kgCO₂e.

**Best for:** Equipment where the carbon cost is tied to total output capacity (e.g., a reactor rated for a certain lifetime throughput).

<Note>
  Project Production amortization requires a **reference node** configured in the production model. This is the gross production output that determines proportional allocation. Without it, batch generation will fail.
</Note>

### No Amortization

Tracks the emission in the ledger **without automated batch deduction**. The total amount is recorded but not spread across batches.

**Best for:** Emissions handled manually in the model, or tracked for audit and record-keeping purposes only.

<Note>
  Once the total amount has been fully amortized (for Project Lifetime or Project Production rules), subsequent batches receive zero deduction. The system prevents over-amortization and will never deduct more than the original total.
</Note>

## Add an embodied emission

<Steps>
  <Step title="Open the Embodied Emissions ledger">
    Navigate to your project's ledger list and open the **Embodied Emissions** ledger.
  </Step>

  <Step title="Create a new entry">
    Click **Add** to open the creation form.
  </Step>

  <Step title="Enter emission details">
    Provide a **Name** (e.g., "Facility Construction" or "Reactor Manufacturing") and the **Total Emissions** value in kgCO₂e.
  </Step>

  <Step title="Select an amortization rule">
    Choose an **Amortization Rule** and fill in the required parameters:

    * **Project Lifetime:** Enter the **Est. Project Lifetime** in years
    * **Project Production:** Enter the **Est. Project Gross Tonnage**
    * **No Amortization:** No additional parameters needed
  </Step>

  <Step title="Add supporting details">
    Optionally add a **Description** and attach **evidence** such as invoices, manufacturer specs, or URLs that support the emission value.
  </Step>

  <Step title="Save">
    Click **Add**. Mangrove creates the emission entry and runs the initial model calculation.
  </Step>
</Steps>

## Connect to your production model

Adding an embodied emission to the ledger is only the first step. To include it in batch calculations, you need to wire it into the production model.

<Steps>
  <Step title="Open the Model Editor">
    Navigate to your project's model and open the **Model Editor**.
  </Step>

  <Step title="Add an amortization node">
    Add an `emission_amortization` operator node to the model tree.
  </Step>

  <Step title="Configure the node">
    Set the node's `embodied_emission_slug` to match the slug of the embodied emission you created. You can find the slug in the embodied emission detail drawer.
  </Step>

  <Step title="Configure the reference node (Project Production only)">
    If using the **Project Production** rule, set the `reference_node_slug` to point to your gross production output node. This tells the system which output to use for proportional allocation.
  </Step>

  <Step title="Connect the output">
    Connect the amortization node's output to your net carbon calculation, typically as a deduction from gross carbon removed.
  </Step>

  <Step title="Test with a batch">
    **Generate a test batch** to verify the amortized amount appears correctly in the batch output.
  </Step>
</Steps>

## Evidence

Each embodied emission can have supporting evidence attached, including files or URLs that document the source of the emission value. This creates an audit trail from reported batch values back to the original data.

Common evidence includes:

* Manufacturer lifecycle assessment reports
* Construction invoices and receipts
* Equipment specification sheets
* Third-party LCA studies

Evidence can be attached when creating the emission or added later through the detail drawer.