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What you’ll learn in this lesson:
  • Decide when a project needs one ledger vs. multiple ledgers
  • Identify the key attributes of every ledger
  • Design a multi-ledger structure for biochar and RNG projects
  • Understand how ledgers chain together through allocations
In Mangrove, mass balance is represented by a series of Ledgers, each tracking the balance of stock at a stage within the Project’s process. You can see a summary of the ledgers on the project Overview, or in the Production Accounting section of the project. Screenshot 2026 02 10 At 9 02 36 PM

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When you need multiple ledgers

In Modules 1–3, you worked with a single ledger — the simplest setup. But when your project has distinct stages where material transforms or accumulates before moving on, you need multiple ledgers.
Keep it simple. Beyond 3 ledgers, the friction of managing balances between ledgers becomes significant. This isn’t a hard rule — it depends on the complexity of your project — but start with fewer ledgers and add more only when a stage genuinely needs its own balance tracking.
The key question to ask: Where does material accumulate before moving to the next stage? Each accumulation point is a candidate for its own ledger.

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Ledger attributes

Every ledger in Mangrove has four key attributes:
The unit can change between ledgers. For example, Ledger 1 might track dry tonnes of feedstock while Ledger 3 tracks tCO2e of carbon delivered. The allocation between them includes a conversion factor.

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Example: Biochar project

A biochar project typically has three distinct accumulation points: How material flows:
  1. Feedstock arrives → credited to Ledger 1
  2. Pyrolysis converts feedstock to biochar → debited from Ledger 1, credited to Ledger 2 (with conversion factor)
  3. Biochar is delivered and sequestered → debited from Ledger 2, credited to Ledger 3 (with carbon content calculation)

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Example: RNG generator

A Renewable Natural Gas project has a similar three-stage structure but with different units:
Notice that Ledger 2 and Ledger 3 use the same unit (MMBtu) — the material doesn’t change form between injection and transmission, but tracking them separately lets you account for pipeline losses and verify that transmitted volume never exceeds injected volume.

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Designing your ledger chain

Use these steps to design ledgers for any project:
1

Map the physical process

Draw out how material flows through your project from input to final output. Identify where material changes form, where it accumulates, and where it leaves the system.
2

Identify accumulation points

Each point where material “sits” before moving to the next stage is a potential ledger. Ask: does this stage need its own running balance?
3

Define units for each ledger

Choose the unit that makes sense for each stage. It’s fine for units to change between ledgers — the allocation handles the conversion.
4

Define credit and debit sources

For each ledger, identify what batch types add to the balance and what removes from it (allocations to the next ledger, or to reports).
5

Map allocation rules

Define how material moves between ledgers. Common methods: proportional by mass, direct assignment (1:1 with a batch), or by conversion factor.

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Check your understanding

Use multiple ledgers when your project has distinct accumulation stages where material sits before moving to the next stage. If material changes form (e.g., feedstock → biochar → tCO2e) or passes through separate physical locations, each stage is a candidate for its own ledger.
Yes. Each ledger can track a different unit — for example, dry tonnes for feedstock, biochar tonnes for production, and tCO2e for delivered carbon. The allocation between ledgers handles the conversion from one unit to another using conversion factors.
Next, learn how to create different batch types for each stage in Lesson 4.3: Multiple Batch Types for Different Stages.