Indonesia’s alumina, aluminium boom could trigger a new captive coal surge, warns CREA

Indonesia’s breakneck build-out of alumina refining and aluminium smelting capacity is raising fresh alarm, with researchers warning the expansion could set off another wave of captive coal power construction while accelerating the drawdown of the country's bauxite ore reserves.

The warning comes from the Centre for Research on Energy and Clean Air (CREA), whose analysts say the pattern now unfolding in Indonesia’s aluminium value chain closely mirrors what already happened in the country's nickel sector, where a rush of downstream processing capacity was built out faster than the resource base or the grid could sustainably support, locking in dependence on off-grid, coal-fired power.

A familiar playbook: Coal-powered downstreaming

Indonesia’s “downstreaming” policy, which bans the export of raw bauxite and incentivises domestic processing into alumina and aluminium, has already reshaped the country's nickel industry, where captive coal capacity has ballooned in recent years to power energy-intensive smelters in Sulawesi and North Maluku.

According to CREA’s own tracking work with Global Energy Monitor, Indonesia's total operational and planned captive coal capacity has climbed past 30 gigawatts (GW), a figure that now exceeds the combined coal fleet of Australia and rivals Germany's total coal capacity.

CREA researchers argue the same dynamic is now taking shape in the bauxite-alumina-aluminium chain. Aluminium production is highly energy-intensive, i.e. producing one tonne of aluminium requires roughly 15,700 kWh of electricity. And with Indonesia's national grid already strained, developers are increasingly turning to dedicated, off-grid coal plants to guarantee stable power for new smelters and refineries.

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Capacity growing far faster than demand or reserves

The scale of the planned build-out is striking. Indonesia’s installed alumina refining capacity, currently around 9 million tonnes per year, could rise to as much as 29.8 million tonnes if every planned and proposed project goes ahead. Aluminium smelting capacity is projected to grow even more sharply — from roughly 1.13–1.97 million tonnes today to as much as 14.9 million tonnes by the mid-2030s, against domestic primary aluminium demand of only around 520,000-700,000 tonnes.

Feeding that expanded capacity at full nameplate output would require an estimated 94 million tonnes of bauxite a year, more than double the roughly 36 million tonnes currently consumed by existing refineries.

State-owned aluminium producer Inalum has already flagged this mismatch, warning that Indonesia's proven bauxite reserves (estimated at around 1 billion tonnes, against total reserves of roughly 2.8–2.9 billion tonnes) could be exhausted in as little as a decade under an aggressive build-out scenario, well short of the 30-year operating life typically built into refinery and smelter investments.

Health, climate and economic costs

CREA's broader modelling of Indonesia’s captive coal trajectory paints a stark picture of the trade-offs involved. Excluding captive coal plants from national retirement targets, the group estimates, could contribute to roughly 27,000 additional air-pollution-related deaths and a cumulative economic burden of around USD 20 billion before the coal fleet is eventually phased out.

Separate CREA research on nickel-processing hubs found that industrial gains from smelter development typically peak within about five years, before rising environmental and health costs begin eroding those economic benefits by year eight.

Regulatory gaps compound the risk. Captive power plants built for “national strategic projects” under Presidential Regulation No. 112 of 2022 benefit from exemptions unavailable to grid-connected plants, and while operators are technically required to cut emissions intensity by 35 per cent within a decade of operation, CREA notes there is currently no public monitoring framework to verify compliance.

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Industry voices echo the warning

CREA's caution aligns with concerns already raised from inside the industry. Inalum president director Melati Sarnita recently urged Indonesia's House of Representatives to pause approvals for new alumina refineries and aluminium smelters, warning that unchecked capacity growth could flood the market, depress prices and shorten the usable life of the country's bauxite reserves — a trajectory she compared directly to the oversupply and price collapse seen earlier in Indonesia's nickel industry.

Au contraire, some industry analysts argue that if total bauxite resources (rather than only proven reserves) are used as the benchmark, the runway could stretch to 30 years or more, turning the debate from one of imminent scarcity into one of pacing and sequencing new project approvals.

What it means for the global aluminium market

Indonesia currently imports more than half of its aluminium consumption, and its push to build a fully integrated bauxite-to-metal value chain has attracted billions of dollars in investment — Indonesian industry estimates put realised investment across alumina and aluminium projects at USD 5.5-6 billion, with total committed and planned investment potentially exceeding USD 30 billion by 2030.

But CREA’s warning emphasises a growing tension at the heart of that strategy. The same coal-fired power that has made rapid downstream expansion commercially viable is also the threat to Indonesia's climate commitments and energy transition potential, including its Just Energy Transition Partnership (JETP) targets and its draft Second Nationally Determined Contribution (SNDC).