Module 4 Exercise: Design & Build Mass Balance with Ledgers

This exercise brings together everything from Module 4: you’ll design and build a multi-ledger mass balance system for Mangrove Biochar. By the end, material will flow from feedstock receipt through biochar production to carbon delivery — with ledger balances that reconcile at every stage. Prerequisites: Complete Lesson 4.1, Lesson 4.2, and Lesson 4.3. Your project should have the batch partitioning and LCA setup from the Module 3 exercise.

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Part 1: Design (30 min)

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1. Identify accumulation points

Map the physical process for Mangrove Biochar. Where does material “sit” before moving to the next stage?

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2. Define each ledger

For each accumulation point, define the ledger attributes:

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3. Map allocations between ledgers

Define how material flows between ledgers:

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Part 2: Build in Mangrove (1.5 hrs)

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Step 1: Create 3 batch types

In your project’s Production Accounting settings, create these batch types:

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Step 2: Create 3 ledgers

Create a ledger for each stage and link it to the corresponding batch type:

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Step 3: Configure allocations

Set up the material flow between ledgers:

1. Feedstock Inventory → Biochar Production
   • When a Production Run batch is created, it should consume feedstock from Ledger 1
   • Configure the allocation to debit from Feedstock Inventory based on feedstock consumed per run
   • Apply the yield ratio conversion (e.g., 5t feedstock → 1.5t biochar)
2. Biochar Production → Carbon Delivered
   • When a Carbon Delivered batch is created, it should draw from Ledger 2
   • Configure the allocation to debit from Biochar Production based on biochar delivered
   • Apply the carbon content conversion (e.g., biochar tonnes × carbon % × 3.67 = tCO2e)

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Step 4: Create test data

Add events representing one month of operations across all stages: 2 Feedstock Deliveries: 2 Production Runs: 2 Biochar Deliveries:

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Step 5: Generate batches and verify mass balance

1. Go to Production Accounting and generate batches for January.
2. Verify that 6 batches are created (2 per stage).
3. Check each ledger’s balance:

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Step 6: Verify end-to-end traceability

For each Carbon Delivered batch, trace the chain back to the source:

1. Open a Carbon Delivered batch (e.g., DEL-001, 4.4 tCO2e)
2. Verify it links to a Biochar Produced batch (PR-001, 1.5t biochar)
3. Verify that links to a Feedstock Receipt batch (FS-001, 5t feedstock)
4. Confirm the conversion math: 5t × 30% yield = 1.5t biochar × 80% carbon × 3.67 = 4.4 tCO2e

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Success criteria

You have completed the Module 4 exercise when:

• 3 batch types created — Feedstock Receipt, Biochar Produced, Carbon Delivered
• 3 ledgers created — Feedstock Inventory (dry tonnes), Biochar Production (biochar tonnes), Carbon Delivered (tCO2e)
• Allocations configured — material flows from Ledger 1 → Ledger 2 → Ledger 3 with appropriate conversion factors
• Test data created — at least 2 events per stage (feedstock deliveries, production runs, biochar deliveries)
• 6 batches generated — 2 per stage, each crediting the correct ledger
• Ledger balances reconcile — credits minus debits match expected values at each stage
• End-to-end traceability — any Carbon Delivered batch can be traced back through production to the original feedstock receipt

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What’s next

You now have a complete multi-stage mass balance system. In Module 5: Integration Testing you’ll learn how to test your full project end-to-end — verifying that events, models, batches, ledgers, and reports all work together correctly.