Analysis: Aluminium oversupply concerns clash with Indonesia’s growing demand and investment reality

By Dominikus, Energy Analyst of Petromindo.com

As the Latin adage goes, ubi commoda, ibi incommode -- every industrial push brings both gains and trade-offs. That is exactly where Indonesia’s bauxite, alumina, and aluminium story now stands. The country is moving deeper into downstreaming, but the speed of that expansion is now under scrutiny after state-owned PT Inalum President Director Melati Sarnita warned lawmakers that unchecked smelter and refinery growth could create oversupply, depress prices, and shorten the life of national bauxite reserves.

Her warning deserves to be taken seriously. In her presentation before Commission VI of the House of Representatives, last week, Melati argued that Indonesia’s installed aluminium smelter capacity could reach 1.975 million tons in 2026 against domestic primary aluminium demand of only around 520,000 to 533,000 tons.

She further argued that output could reach 4.9 million tons by 2035 while local demand would be only around 707,000 tons, and that if all proposed smelter projects proceed, potential aluminium capacity could rise as high as 14.9 million tons. On the alumina side, she said there are around 13 companies planning refineries, with installed refinery capacity around 9 million tons in 2026 and potential capacity reaching 29.8 million tons, requiring 80 million to 94 million tons of bauxite annually if all projects run. Using a proven bauxite reserve base of 1 billion tons and total reserves of 2.8 billion tons, she concluded that proven reserves could last less than 10 years and total reserves only around 28 years under an aggressive build-out scenario.

Read strictly on its own terms, that argument is internally coherent. A capacity base of 1.975 million tons is about 3.7 times domestic demand of 533,000 tons. An output level of 4.9 million tons is about 6.9 times a 707,000-ton domestic market. A 14.9 million-ton capacity base would be more than 21 times that same demand level. If the frame is only today’s or near-term domestic primary aluminium demand, the industry does look too big. But that is also where the weakness of Inalum’s case begins. It is anchored too tightly to a narrow, near-term demand frame, while the rest of the market data points to a broader structural shift.

Demand and investment: A structural shift already underway

The first missing piece is long-term demand. The Ministry of Industry outlook shows a much steeper demand curve than the one implied in Melati’s presentation. National aluminium demand is projected to grow from around 1.1 million tons in 2023 to 2024 to more than 4.6 million tons in 2025 to 2029, exceed 6.3 million tons in 2030 to 2034, surpass 8.2 million tons in 2035 to 2039, and rise above 10 million tons by 2039 to 2045, with electric vehicles and solar deployment as the main structural drivers.

That does not mean Indonesia will need 4.6 million tons every year during 2025 to 2029. But even if that number is averaged over five years, it implies annual demand of around 931,000 tons, already far above the 520,000 to 533,000 tons cited by Melati for the near term. If the 2035 to 2039 total of 8.2 million tons is averaged, the implied annual level is around 1.64 million tons, more than twice the 707,000-ton demand figure cited in her presentation.

In other words, Melati’s oversupply argument is strongest under a short-term, narrow primary-metal lens. Once the wider industrial demand trajectory is brought in, especially demand linked to EVs, solar panels, and electrification, the same conclusion becomes much less clear-cut.

The second missing piece is that Indonesia is not building only for the current domestic market. Petromindo.com’s industry update already showed that the country had moved well beyond a paper pipeline. It estimated realized investment across alumina and aluminium projects at roughly US$5.5 billion to US$6 billion, with total committed and planned investment potentially exceeding US$30 billion by 2030. The same report noted that more than 42 million tons per year of smelter-grade alumina capacity and more than 10.4 million tons per year of aluminium ingot capacity were in the broader development pipeline.

West Kalimantan’s own official project data reinforces that point. The DPMPTSP Kalbar booklet shows realized bauxite smelter investment of more than Rp42.6 trillion, including major names such as PT Borneo Alumina Indonesia, PT Well Harvest Winning Alumina Refinery, PT Borneo Alumindo Prima, PT Kalimantan Alumina Nusantara, PT Supreme Alumina Indonesia, and PT Westerfield Alumina Indonesia. That is roughly US$2.7 billion at a Rp16,000 exchange rate, meaning West Kalimantan alone accounts for a very large portion of Petromindo’s national realized-investment estimate. This is not a story of hypothetical future interest. It is already a capitalized industrial build-out.

Reserves and pricing: Where the argument becomes fragile

The third issue is reserves, which is the most sensitive part of the entire debate. This is where Melati’s presentation is strongest emotionally, but also where it becomes most vulnerable analytically. Her reserve-life argument depends on a proven bauxite reserve base of only 1 billion tons. On that basis, annual refinery feedstock demand of 80 million to 94 million tons would indeed reduce reserve life to around 10.6 to 12.5 years. That is a real concern for a 30-year industrial asset.

But in Petromindo.com’s 2026 outlook in this sector drawing on a presentation by the Geological Agency, uses a very different reserve base. It states that Indonesia’s proven bauxite ore reserves are about 2.8 billion tons, with total resources of around 7.7 billion tons. If the same 80 million to 94 million ton annual consumption assumption is applied to 2.8 billion tons of proven reserves, the reserve life changes materially to around 29.8 to 35 years, not less than 10. If the denominator is total resources rather than proven reserves, the resource life is longer still.

That difference is not academic. It changes the policy conclusion. If the correct operational planning base is 1 billion tons, Melati’s moratorium logic gains force. If the broader reserve base used by the Geological Agency is the better benchmark, then the argument shifts from imminent scarcity to managed pacing.

The fourth issue is pricing, and here the argument from Inalum appears to blur alumina and aluminium in a way that should be handled carefully. In her presentation, Melati said “the price of aluminum is around $300 per ton, which is the lowest level since 2021.” That figure does not line up with the aluminium market. It is much closer to alumina.

SMM’s early 2026 aluminium review shows LME aluminium prices broadly in the US$2,200 to US$3,200 per ton range, while its alumina outlook suggests a looser market from 2026 onward due to significant capacity additions. This distinction matters because the risk profile is not the same across the chain. For alumina, the oversupply risk is more immediate. For aluminium, the global market is still expected to remain in a relatively tight balance in 2026 before gradually shifting toward surplus after 2027.

Global market and structural demand: Why expansion still holds

The fifth issue is the global market itself. Inalum argues that much of future Indonesian output would be destined for export and that Indonesia, even at 5 million tons, would still be too small to influence global prices in a market dominated by China. That point is fair.

But being a price taker is not a reason to avoid industrialization. It is the normal condition for most commodity producers. What matters is cost position, integration, and market access.

SMM notes that energy accounts for roughly 30% to 35% of aluminium production costs, while the 2026 outlook highlights power availability as the central constraint in Indonesia’s aluminium development. This shifts the discussion from “whether to expand” toward “which projects are viable.”

The sixth point is that EV and solar demand are no longer marginal. SMM data shows stable to positive demand in automotive and photovoltaic sectors, while the outlook places EV manufacturing, solar deployment, and electrification at the center of future aluminium demand.

This means Indonesia’s aluminium expansion should be understood within the context of the global energy transition. Aluminium is increasingly becoming a strategic material, not just a cyclical commodity.

Conclusion: Not a moratorium, but a filter

None of this means Melati’s warning should be dismissed. She is right to highlight risks of overcapacity, resource pressure, and the lessons from the nickel sector.

But the broader data suggests that the issue is not simply oversupply.

Indonesia is in a transitional phase, where capacity expansion runs ahead of demand realization. This is not unusual in capital-intensive industries.

The real question is not whether Indonesia should slow down entirely, but how it should move forward.

Rather than imposing a blanket moratorium, Indonesia needs a stronger filter, prioritizing integrated, power-secure, and economically viable projects while delaying weaker ones.

The debate, ultimately, is not about stopping expansion.

It is about ensuring that expansion is disciplined enough to sustain Indonesia’s long-term position in the global aluminium market.

Editing by Reiner Simanjuntak