脱碳路径：已知措施可降低约40%，绿色铁可进一步降低

10.1 The levers, in order of size

Figure 10.1 applies a sequence of levers cumulatively to the full build-out. Each parameter stays within the range in the RC-1 reference configuration, except the hydrogen-based iron step, which is derived from published process data (Chapter 6). The sequence is illustrative; levers can be pursued in parallel and their order does not imply timing.

Source: WP06 model on the Cameroon Steel reference configuration RC-1 (planning estimate) [S90]; DRI power penalty [S15]; hydrogen-based iron intensity derived from [S15]; IEA near-zero threshold [S06].

Table 10.1 Pathway levers and their illustrative effect at 1 Mtpa

Source: WP06 model on the Cameroon Steel reference configuration RC-1 (planning estimate) [S90] (Annex A). Values are illustrative; annual effects at nameplate output.

Three features stand out. First, the operational levers inside the works (efficiency, direct carbon, reheating) are real but small, about 0.04 t per tonne together. They should be pursued because they also save money, but they do not change the plant’s carbon position. Second, the two levers that matter most in the medium term, the grid and the iron units, are largely outside the works’ fence: they depend on contracts and on suppliers. Third, the step from 0.35 to 0.26 t requires a change in how iron is made, which is why green iron, not furnace practice, is the long-term frontier.

Even the end state does not reach near-zero. At about 75% scrap, the IEA’s threshold corresponds to about 0.15 t per tonne of product [S06]. Closing the remaining gap would require a grid closer to zero, hydrogen-based reheating or electrification of reheating, and furnace direct emissions reduced further, for example with biogenic carbon in place of fossil charge carbon. These are options for the 2040s, not plans.

10.2 What the levers cost, and who pays

The levers differ as much in cost as in size. The operational levers (furnace and mill efficiency, lower electrode and carbon consumption, hot charging) usually pay for themselves through lower energy and consumable costs, which is why they are standard practice in well-run electric-arc works. The grid lever depends on the terms of the power contract: in Cameroon, realised high-voltage prices in 2025 ranged from about 18.4 FCFA per kWh under legacy contracts to a regulatory estimate of about 105 FCFA per kWh for the cost-reflective average across all customers [S50][S54], so firm, identified low-carbon supply may carry a premium over the cheapest available energy. The iron-unit levers depend on the market for low-carbon DRI and HBI, which is still thin and which analysts expect to tighten as demand for DR-grade feed outstrips supply [S11].

The hydrogen step is the expensive one. The Energy Transitions Commission estimated that fully decarbonising steel would cost about US$60 per tonne of CO₂ abated, adding about US$115 to a tonne of steel, falling to about US$25 per tonne of CO₂ and US$50 per tonne of steel where very cheap clean electricity is available [S09]. The Mission Possible Partnership estimated a premium of about US$175 per tonne, about 40%, for near-zero primary steel around 2030, adding about 2% to the price of a building [S08]. Carbon border measures will cover part of that gap for exported products: Chapter 5 showed an illustrative CBAM differential of about €70 to €160 per tonne between RC-1 product and an average blast-furnace product by 2034 at today’s certificate price; because CBAM prices the DRI in RC-1’s charge, hydrogen-based iron units at 0.2 t per tonne would also cut RC-1’s own charge by about €15 per tonne (derived). For the domestic and regional market, where no carbon price applies, the hydrogen step would need either a buyer’s premium, concessional climate finance or very low-cost hydro, and probably all three.

The practical conclusion is a sequence: pursue the operational levers immediately because they pay; secure the grid and iron-unit levers through contracts because they are where most of the carbon is; and develop the hydrogen option as evidence and economics allow.

10.3 An indicative trajectory

Figure 10.2 places the pathway on an indicative timeline. Phase 1 would operate at about 0.58 t per tonne from its first heat, targeted for the second half of 2030, and through its ramp-up in 2031; the full build-out, if it proceeds after 2034, would hold that level; the known levers could bring it to about 0.35 t in the late 2030s; and hydrogen-based iron units could bring it to about 0.26 t in the 2040s. Scopes 1 and 2 would fall from about 0.32 t per tonne in Phase 1 (about 0.33 t at full build-out) to about 0.20 t, mostly through the grid.

Source: WP06 model on the Cameroon Steel reference configuration RC-1 (planning estimate) [S90]; phasing from the RC-1 indicative schedule [S90]; worldsteel scrap-EAF average [S01].

The trajectory is gated at each step. The grid lever needs the transmission reinforcements and supply contracts discussed in Chapter 3. The iron-unit levers need suppliers willing to certify their carbon content and, for hydrogen-based iron, firm low-carbon electricity at a cost that a carbon price or a buyer’s premium can bridge. The scrap lever needs a collection system that does not yet exist at scale. Cameroon Steel would report progress against each lever annually, so that the trajectory can be tested against evidence rather than intentions.

10.4 Measurement, reporting and verification from the first heat

The pathway is only as credible as the measurement behind it. The monitoring plan for RC-1 would rest on four principles:

1. One dataset, several reports. A single, metered dataset of carbon inputs (electrodes, charge carbon, fluxes, gas), electricity by consumer, purchased iron units with their supplier data, and production by product feeds every report: the GHG Protocol corporate inventory, the ISO 14404 site intensity, CBAM embedded emissions and EPDs (Chapter 2).
2. Supplier data for iron units. Every cargo of DRI or HBI comes with verified carbon data from its producer, prepared on the CBAM or ISO 14404 basis.
3. Independent verification. An accredited third party verifies the annual inventory against ISO 14064-3 [S101] and the CBAM rules, and verifies EPDs under the applicable programme.
4. Public disclosure. An annual climate report publishes the inventory, the key performance indicators in Table 10.2 and progress against the pathway.

Table 10.2 Key performance indicators for the RC-1 climate report

Source: Cameroon Steel, monitoring design principles; standards as cited in Chapter 2.

10.5 Ten recommendations

Table 10.3 sets out the ten actions that follow from this paper, with the party that leads each and an indicative timing. They are written as Cameroon Steel’s intentions and requests; they are not contractual commitments.

Table 10.3 Ten recommendations

Source: this paper, Chapters 1 to 9.

10.6 What government and partners can do

Several of the levers sit with public institutions. Cameroon Steel would welcome progress in five areas, which would benefit every industrial electricity user and not only the steel sector:

• Grid reinforcement and firm supply for industrial zones, including completion of the transmission links that deliver hydro output to the coast [S51][S55].
• A registry for electricity attribute certificates or an equivalent mechanism, so that contracted low-carbon supply can be evidenced and not double-counted.
• A national framework for industrial greenhouse gas reporting and verification, consistent with international methods, which would also strengthen Cameroon’s ability to document carbon prices or emissions for export markets.
• Standards for recycled aggregates, so that steel slag and other secondary materials can be used in public works with confidence.
• Support for ore beneficiation studies, consistent with the local-transformation objectives of the Mining Code [S86] and the KPIZ steel cluster [S74], so that the DR-grade question is answered with public data.

10.7 Conclusion

Cameroon has an unusual combination of assets for low-carbon steel: a hydro-dominated grid, large undeveloped hydro potential, iron ore under development and a deep-water port with an industrial zone that names steel among its clusters. An electric-arc works at Mboro could use the first of these from its first heat to make steel at about a third of the world’s average carbon intensity. The others could, over two decades and under conditions this paper has set out, allow Central Africa to make its own low-carbon iron.

The difference between that possibility and a claim is measurement. A works that measures, verifies and publishes its carbon performance, and that contracts for low-carbon power and iron units with the same care it gives to cost and quality, will be able to turn Cameroon’s natural advantages into a competitive one. That is the course this paper recommends.