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View all search resultsBlackout in Sumatra and the threat to Indonesia's energy transition
Indonesia’s power system is still built on a decades-old paradigm, a handful of large power plants strung together by long transmission lines, with limited flexibility and little redundancy.
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A vendor prepares drinks for customers on May 23, 2026, during a power outage in Nagari Kasang, Padang Pariaman, West Sumatra. (Antara/Fitra Yogi)
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ast month’s massive blackout across Sumatra, triggered by a single break in the 275 kilovolt (kV) Muara Bungo–Sungai Rumbai transmission corridor in Jambi, left millions without power for hours.
One lightning strike, one corridor and the whole interconnected cross-provincial grid went down. The big question is why a localized disturbance that should have been contained instead cascaded into a system-wide failure.
The honest answer is Indonesia’s power system is still built on a decades-old paradigm, a handful of large power plants strung together by long transmission lines, with limited flexibility and little redundancy.
When one part of that chain fails, the whole thing goes down fast. What makes this more than a reliability story is the context. Indonesia’s energy transition has been almost entirely fixated on building generation: how many gigawatts of solar, how many geothermal projects, how many coal plants to retire.
The grid, transmission, distribution, protection systems, control architecture, get treated with secondary importance, easy to defer. But this is where the nervous system of the entire power sector lives.
We have been neglecting it for years. A 500 kV transmission backbone for Sumatra was planned over a decade ago, conceived as an electricity superhighway connecting the island’s provinces. Target completion was 2019 but we are well past that, and there is little to show for it. The system still leans heavily on 275 kV networks that were never designed for today’s load, let alone tomorrow’s.
The stakes are now considerably higher. Indonesia is in the middle of an industrial transformation: downstream nickel processing, electric vehicles, hyperscale data centers, new green industrial zones. None of these can tolerate hours without power. A smelter losing power mid-process. A hospital during surgery. A data center serving millions of users. These are the industries Indonesia is actively courting as investors.
Investors do not look at tariff prices alone. They also look at reliability. The Sumatra blackout sent a signal that every investment promotion board in the country should be worried about.
So what must be done? The government and state electricity company PLN must commission a genuinely independent technical investigation, one that goes well beyond attributing the failure to a storm.
A failure of the transmission line is not the first time. In June 2024, the failure of the 275 kV transmission line of Lubuk Linggau – Lahat caused millions of consumers in the southern Sumatra system to be left in the dark. But no single report of serious investigation of this failure is known to the public.
Spain’s major blackout last year gives an example for Indonesia. Right after the incident authorities investigated transmission bottlenecks, protection coordination failures, reserve margins and system balancing under high renewable penetration. Their finding was unambiguous: blackouts are almost never caused by a single factor. A routine disturbance escalates into systemic failure when multiple layers of resilience are simultaneously weak. Indonesia needs that same honest reckoning with itself.
Grid investment must also stop being the poor cousin of generation investment. Expanding transmission capacity, building in redundancy and modernizing protection systems are the foundation on which any credible energy transition depends. An energy transition without grid reform will produce a more vulnerable system, not a cleaner one.
Grid investment is not profitable. Therefore the government must step in to provide concessional finance and coordinate low cost financing with multilateral development banks and bilateral cooperation.
Indonesia needs to take decentralization seriously, a point that rarely gets the attention it deserves.
The technology now exists for cost-effective rooftop solar-plus-battery systems at scale. Industrial zones can operate their own microgrids. Critical facilities like hospitals, data centers and airports need distributed backup systems capable of operating autonomously when the main grid fails. This is the architecture of a more resilient national power system.
PLN itself must evolve: from a utility that operates power plants and poles into an adaptive, digitalized energy system operator capable of managing extreme weather events, integrating variable renewables and handling the complex balancing demands of a 21st century grid.
Making renewable power plants is the easy part. Building the grid that holds everything together? That is the hard part. And it is the part we keep putting off.
The Sumatra blackout is a warning about infrastructure we have underfunded, reforms we have postponed and a fragility at the heart of an energy transition that still does not have its foundations right.
The biggest challenge facing Indonesia’s energy future is not building low-carbon power plants. It is building an electricity system strong enough to carry the economy of the future.
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The writer is CEO of the Institute for Essential Services Reform (IESR).
