Renewable Carbon Index calculator.
Quantify what fraction of the carbon in your product comes from renewable sources — biomass, captured CO₂, or recycled carbon streams.
What is the Renewable Carbon Index — and why does it matter?
The Renewable Carbon Index (RCI) quantifies what fraction of the carbon atoms in a chemical product originate from renewable sources — biomass, captured CO₂ (CCU), or recycled carbon — rather than from fossil feedstocks. As chemical production shifts away from petroleum and coal, RCI provides a clear, product-level signal of how far a synthesis has decoupled from fossil carbon.
RCI is closely linked to Principle 7 of Green Chemistry — Use of Renewable Feedstocks — and is increasingly cited in sustainability reports, product carbon footprints, and bioeconomy policy frameworks.
The formula
| Symbol | Term | Units |
|---|---|---|
| $\text{RCI}$ | Renewable Carbon Index | % (0–100); ideal value = 100% |
| $C_{\text{renewable}}$ | Mass of carbon in the product that originates from renewable sources (biomass, CO₂ capture, recycled carbon) | g C (or mol C) |
| $C_{\text{total}}$ | Total mass of carbon in the product | g C (or mol C) |
Carbon inputs can be tracked at the feedstock level (mass of carbon from each source) or calculated from molecular composition once product stoichiometry is known. Both mass-based and mole-based inputs give the same RCI, provided units are consistent.
What counts as renewable carbon?
| Source | Renewable? | Notes |
|---|---|---|
| Biomass / bio-based feedstocks (starch, cellulose, sugars, vegetable oils, lignin) | Yes | Carbon fixed from atmospheric CO₂ via photosynthesis |
| Captured CO₂ (CCU / CCUS) | Yes | CO₂ used as a C1 building block (e.g. polycarbonate, methanol, urea) |
| Chemically or mechanically recycled carbon | Yes | Polymer depolymerisation, pyrolysis oils from waste plastics |
| Petroleum, natural gas, coal | No | Fossil carbon — adds net CO₂ to the atmosphere on combustion |
| Inorganic carbon (carbonates, CO₂ from fossil combustion) | No | Not considered renewable unless specifically captured from a non-fossil source |
Typical RCI values by sector
| Product / sector | Typical RCI | Key driver |
|---|---|---|
| 100% bio-based polymer (PLA, PHB, bio-PE) | 100% | All carbon from fermentation feedstocks |
| Partially bio-based polymer (bio-PET 30%) | ~30% | Bio-based mono-ethylene glycol; fossil terephthalic acid |
| Conventional petrochemical (PE, PP, PVC) | 0% | All carbon from fossil naphtha or ethane |
| Bio-sourced chemical with fossil co-feedstock | 10–80% | Depends on proportion of bio-carbon in the molecular structure |
| CO₂-based polymer (polypropylene carbonate) | ~29% | One CO₂ unit per repeat unit; the remainder is fossil propylene oxide |
Strengths and limitations
Strengths
- Simple, product-level metric — directly traceable to molecular structure
- Applicable at design stage (theoretical) or from experimental data
- Consistent with ISO 16620 (bio-based content) and EU taxonomy frameworks
- Complementary to carbon footprint — high RCI does not guarantee low GWP
- Easily decomposed by feedstock source for process redesign guidance
Limitations
- Measures carbon origin, not environmental impact — land use, water, and biodiversity are not captured
- Does not distinguish between sustainably and unsustainably sourced biomass
- A high RCI does not mean a low lifecycle carbon footprint (indirect emissions matter)
- Mechanically recycled carbon may still carry fossil origins — depends on accounting boundary
- Requires reliable supply-chain data on feedstock carbon fractions
RCI in context: complementary metrics
| Metric | What it measures | Relationship to RCI |
|---|---|---|
| RCI (Renewable Carbon Index) | Fraction of carbon in the product from renewable/circular sources | — |
| Bio-based content (ISO 16620) | Mass fraction of the product derived from biological origins (14C method) | Often used synonymously with RCI when bio-based feedstocks are the only renewable source |
| Carbon Footprint (GWP) | Net greenhouse gas emissions over the product lifecycle (kg CO₂-eq) | A high RCI often, but not always, correlates with lower GWP |
| E-factor | Mass of waste per mass of product | Independent of carbon origin — measures process efficiency |
| Atom Economy | Theoretical fraction of reactant mass incorporated in product | Independent of carbon origin — measures molecular efficiency |
Product & experiment details
Carbon streams in the product
Enter each carbon-containing feedstock or structural component of the product. For each, record the mass of carbon that ends up in the product (not the total mass of the feedstock) and select whether that carbon is from a renewable or fossil source. Use consistent units (g C or mol C) throughout.
| Carbon source / feedstock | Source type | Carbon in product (g C) | % of total carbon |
|---|
Results
Carbon by source type
Renewable vs. fossil carbon balance
Detailed breakdown & interpretation
| Carbon source | Type | Carbon in product (g C) | % of total C | Renewable? | Visual |
|---|---|---|---|---|---|
| Enter carbon streams above to see breakdown. | |||||
Interpretation
Save & load sessions
Sessions are stored in your browser only. No data leaves your device.
Export
Export your RCI calculation as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.
Where can I read more?
References are sorted alphabetically by first author.
- P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998. ISBN 978-0-19-850698-0. — Original statement of the 12 Principles; Principle 7 addresses renewable feedstocks.
- M. Carus and L. Dammer, The Circular Bioeconomy — Concepts, Opportunities, and Limitations, nova-Institute, 2017. nova-institute.eu. — Framework for defining and measuring renewable carbon sources including biomass, CO₂, and recycled carbon.
- M. Carus et al., Renewable Carbon Index (RCI) — Defining a New Metric for the Chemical Industry, nova-Institute, 2021. renewable-carbon.eu. — Primary source for the RCI definition and its application across chemical sectors.
- ISO 16620-1:2015. Plastics — Biobased content — Part 1: General principles. International Organisation for Standardisation. — Standard for measuring bio-based carbon content using 14C isotope ratio analysis.
- J.-P. Lange, Renewable Feedstocks: The Problem of Catalyst Deactivation and its Mitigation, Angew. Chem. Int. Ed., 2015, 54, 13186–13197. DOI. — Discussion of bio-based feedstock challenges relevant to RCI improvement.
- R. A. Sheldon, Green and sustainable manufacture of chemicals from biomass: state of the art, Green Chem., 2014, 16, 950–963. DOI. — Overview of bio-based chemical production and renewable carbon utilisation.
Contributors
Roles follow the CRediT taxonomy (Contributor Roles Taxonomy), adapted for educational software. Hover a contributor's name for a summary, or a column header for the definition of that role.
| Contributor |
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