Biosourced Nickel and the Decarbonisation of Stainless Steel: How the Bioeconomy Answers the CSRD and CBAM Challenge

Introduction: the carbon blind spot of the stainless steel industry

Stainless steel is everywhere in the modern economy — kitchens, hospitals, chemical reactors, energy infrastructure and mobility equipment. And yet its production chain remains one of the most carbon-intensive in global manufacturing. Nickel, the key metal that gives stainless its corrosion resistance, is mainly produced through highly energy-intensive pyrometallurgical processes — RKEF ferronickel and nickel pig iron (NPI) — both massively fuelled by fossil fuels, primarily in Asia.

Against that backdrop, cutting Scope 3 emissions — the indirect emissions tied to the upstream supply chain — is one of the most complex challenges facing stainless steel manufacturers. Those emissions nonetheless account for the heaviest share of stainless steel's life cycle. The emergence of biosourced nickel through phytomining offers an unprecedented technological answer to that challenge.

1. Anatomy of stainless steel's Scope 3

1.1 The three levels of industrial emissions

The GHG Protocol distinguishes three levels of emissions. Scope 1 covers direct emissions from a company's own facilities. Scope 2 covers emissions linked to purchased energy. Scope 3 encompasses all other indirect emissions — upstream (extraction and processing of raw materials, transport of inputs) and downstream (use and end of life of products). For a stainless steel producer, metallic raw materials contribute between 30% and 60% of total life-cycle emissions for a standard steel, depending on the origin of the materials and the energy mixes of the producing countries.

1.2 The carbon intensity of nickel by production route

The carbon intensity of nickel varies considerably by production route and geography — differences that have a major impact on the final carbon footprint of stainless products:

• RKEF ferronickel (Indonesia, Philippines): 20 to 40 tCO₂ equivalent per tonne of nickel — the most carbon-intensive route, coal-fired
• NPI pig iron (China, Indonesia): 15 to 35 tCO₂/t Ni depending on the process
• Nickel from sulphide ores (Canada, Russia, Finland): 5 to 15 tCO₂/t Ni — more efficient hydrometallurgical processes
• Biosourced nickel through phytomining (preliminary estimates): 3 to 8 tCO₂/t Ni — with the potential for further reductions through the integration of renewables
• Secondary recycled nickel: 1 to 4 tCO₂/t Ni — the least carbon-intensive route, constrained by scrap availability

These figures illustrate how much rides on the choice of supply source: replacing a tonne of Indonesian ferronickel with a tonne of biosourced nickel can cut the associated emissions by 80% to 90%.

2. The regulatory framework: CSRD, CBAM and the Critical Raw Materials Act

2.1 CSRD: carbon transparency becomes a legal obligation

The CSRD directive, which has been phasing in since 2024, requires the companies concerned to disclose detailed non-financial information in line with the ESRS standards. For stainless steel manufacturers, that means an exhaustive and auditable declaration of their Scope 3 emissions covering the entire supply chain. It is a structural turning point: for the first time, buyers will have to document and make public precise information on the carbon footprint of every tonne of nickel they purchase.

In that context, biosourced nickel with a documented carbon footprint, traceable to the plot and verifiable by a third-party auditor, acquires considerable differential value — not only environmentally, but directly in terms of regulatory compliance.

2.2 CBAM: the cost of carbon enters purchase prices

The CBAM mechanism entered its transition phase in October 2023, with full application and payment scheduled from January 2026. European importers of carbon-intensive products will have to buy CBAM certificates matching the ETS carbon price. By way of illustration, ferronickel emitting 35 tCO₂/t Ni at a carbon price of €80/tCO₂ generates a CBAM charge of around €2,800 per tonne imported. That structural price increase directly strengthens the economic competitiveness of low-carbon biosourced nickel.

2.3 The Critical Raw Materials Act: the sovereignty imperative

The CRMA adopted in March 2024 sets quantified strategic autonomy targets for the EU across 34 critical raw materials including nickel: extracting 10%, processing 40% and recycling 15% of annual needs on European territory by 2030. Phytomining is perfectly positioned to contribute to those targets: extraction and processing entirely within Europe, with no major environmental impact.

3. The carbon advantage of biosourced nickel

3.1 Where the emissions reductions come from

A preliminary life-cycle analysis of the phytomining process highlights several emission-reduction mechanisms:

• Plant growth phase: partial sequestration of atmospheric CO₂ during the growing cycle. That sequestration belongs to the short biogenic carbon cycle, treated as neutral in carbon accounting under international conventions
• Elimination of long-distance transport: unlike Asian ferronickel, which travels thousands of kilometres by sea to reach Europe, biosourced nickel can be produced locally
• No explosives and no heavy mining machinery
• A treatment process with lower energy intensity than RKEF furnaces operating at 1,500-1,600°C
• Decarbonisation potential through renewables: the modular thermochemical treatment facilities lend themselves well to integrating renewable energy

3.2 Traceability as a core competitive asset

Beyond the absolute figures, a major competitive advantage lies in the granular traceability that phytomining makes possible. Every tonne of bio-ore can be attributed to a geolocated plot, a documented growing cycle with certified agronomic practices, and a treatment batch with its parameters on record. That end-to-end traceability answers precisely what buyers under CSRD constraints need.

The granular carbon traceability of biosourced nickel turns an anonymous commodity into a certifiable asset — a fundamental break in the sourcing logic of manufacturers operating under ESG and CSRD constraints.

4. Strategic implications for value chain players

4.1 For stainless steel producers

For steelmakers, bringing biosourced nickel into their supply mix is an opportunity to cut their Scope 3 in a documented and verifiable way, without altering their existing production processes. The compatibility of bio-ore with conventional metallurgical production flows is one of the sector's major strengths: it requires no investment in new facilities, simply an adaptation of supply contracts and quality certification processes.

4.2 For industrial consumers of stainless steel

For the procurement departments of large consuming groups — carmakers, equipment suppliers, pharmaceutical groups, energy infrastructure operators — the development of a certified biosourced nickel offer opens new avenues for building defensible Scope 3 carbon accounts. Supply contracts for "stainless steel with a certified low carbon footprint" could become a competitive advantage in public tenders subject to strengthened environmental criteria.

4.3 For ESG investors and transition funds

The nickel phytomining sector sits at the intersection of several converging megatrends: the bioeconomy, European industrial sovereignty, the energy transition and the circular economy of metals. The regulatory convergence of CSRD, CBAM and CRMA creates fertile ground for these assets to be valued more highly over time. The best-suited financing structures combine venture capital equity for the R&D and demonstration phases, infrastructure debt to finance cultivated land, and green bonds for treatment facilities.

5. Vertical climate integration: a new industrial paradigm

The emergence of biosourced nickel illustrates a broader phenomenon: "vertical climate integration". Manufacturers are no longer content to buy carbon credits; they are co-developing the technological solutions that decarbonise their supply chain at source. This approach creates durable value by structurally reducing future regulatory costs, securing supply against geopolitical risk, and building a lasting competitive advantage over rivals who remain dependent on carbon-intensive nickel.

Vertical climate integration represents the next frontier of sustainable industrial strategy: decarbonising not merely your own plant, but reconfiguring your entire supply chain to eliminate its emissions at source.

Conclusion

Decarbonising stainless steel will not come from electrifying furnaces or greening power mixes alone. It requires a fundamental overhaul of the supply chains for critical metals — starting with nickel. Industrial phytomining offers an unprecedented answer to that challenge: a technology that simultaneously reduces Scope 3 emissions, geopolitical supply risk, and dependence on carbon-intensive third countries. Against a rapidly changing CSRD + CBAM + CRMA backdrop, the window of opportunity for this sector will only widen.