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Indonesia has taken a bold and likely problematic step with the announcement of its first, early stage regulatory approval for a nuclear power project. Thorcon International, a Singapore-based developer of molten salt reactors, has received permission from Indonesia’s regulator to evaluate a site for a demonstration plant on Kelasa Island. For a country of more than 270 million people with electricity demand that is still growing rapidly, this might appear to be a turning point. Yet if one examines history, technology, and the context in which this project is being launched, the chances of it succeeding look vanishingly small.
Indonesia is the world’s largest archipelago, stretching across more than 17,000 islands, with only about 6,000 of them inhabited. This geography creates enormous challenges for the national grid, which is fragmented into multiple regional systems rather than a single interconnected backbone. Java and Sumatra host most of the country’s transmission infrastructure, while many outlying islands depend on small isolated grids. Remote communities often rely on diesel generators for electricity, which are expensive to operate and create significant local pollution.
Economically, Indonesia is driven by resource extraction and exports such as coal, palm oil, nickel, and natural gas, as well as a growing manufacturing sector and services economy. Tourism, fisheries, and agriculture remain important contributors, particularly on islands outside the main industrial hubs. This combination of dispersed population, reliance on fossil fuels, and economic dependence on resource sectors shapes both the urgency and the difficulty of Indonesia’s energy transition.
Indonesia still relies heavily on coal, which provides about 61% of its electricity, with natural gas and oil supplying most of the rest. Renewables remain modest, with hydropower contributing around 7%, geothermal about 5%, and solar just 1%. The state electricity plan sets out 71 GW of new capacity by 2034, with about 17 GW from solar, 16 GW from hydro, and 5 GW from geothermal. Alongside this, the government has announced a target of 10 GW of nuclear capacity by 2040, marking its first commitment to nuclear power.
If delivered, these additions would lift renewables to roughly 35% of the national mix while also introducing nuclear into the system for the first time. Looking further ahead, Indonesia targets 75 GW of new renewable capacity by 2035, supported by more than 10 GW of storage, reflecting the scale of investment needed to diversify away from coal and meet climate commitments.
Nuclear power has only succeeded when certain conditions were in place. In the mid-twentieth century, large economies aligned nuclear energy programs with nuclear weapons programs. They standardized on one design, built dozens of gigawatt-scale plants in sequence, trained workforces through government-led programs, and maintained focus for decades. Those programs were not efficient by today’s standards, but they were coherent and well-resourced.
Countries that did not follow that formula, such as Canada’s stop-start approach with CANDUs or the the last couple of decades of western nuclear reactor builds, ended up with mixed results and rising costs. Even China, which has mastered megaproject delivery, is struggling with nuclear because it has spread effort across too many designs and has not locked into the necessary standardization. While nuclear advocates in the west point to China’s build out as impressive, it is years behind on targets and falling further behind. It only achieved its 2020 target in 2024, is still well under its 2% of grid capacity target for 2025 and its scheduled construction through 2030 will leave it tens of GW off that target.
Indonesia has none of the ingredients that historically led to nuclear success. It has no prior nuclear fleet, no experience operating reactors, no large-scale nuclear workforce, no plans to build nuclear weapons and no tradition of standardized reactor builds. It’s not building dozens of standard and proven GW-scale reactors, but only 10 GW in total, starting with a 500 MW unproven design, and not necessarily repeating that one solution multiple times. So far they appear to have little political opposition to nuclear, but that doesn’t mean the bipartisan support required for a two to four decade strategic national construction program. The country is signatory to the nuclear Non-Proliferation Treaty and has eliminated highly enriched uranium that might be transferable to nuclear weapons from the countyr, so there is military strategic alignment and discipline to call upon.
The choice of a molten salt reactor adds another layer of difficulty. Molten salt designs were first tested at Oak Ridge in the 1960s. They worked in the lab but ran into issues with corrosion, material embrittlement, plugging of salt lines, and complex chemistry that had to be actively managed. They never scaled beyond a few megawatts of thermal output. In recent years, startups from North America to Scandinavia have revived the concept, promising walk-away safety and lower costs. Yet not a single one has delivered a commercial plant. Thorcon itself has never built or operated a reactor, anywhere. It is proposing to build large sealed modules in shipyards and tow them to Indonesia, an approach that exists only on paper.
Thorcon’s name hints that the red flag of thorium might be in the mix. Thorium has long been held out as an alternative path for nuclear energy. Thorium-232, when exposed to neutrons inside a reactor, transmutes into uranium-233, which is fissile and can sustain a chain reaction. Advocates have argued that thorium is three to four times more abundant than uranium, produces less long-lived waste, and creates inherent barriers to proliferation because the uranium-233 it breeds is contaminated with hard gamma-emitting uranium-232. Experiments dating back to the 1960s, including the Oak Ridge molten salt reactor experiment in the United States and the Shippingport breeder reactor’s final thorium core, proved that the fuel cycle was technically viable.
Germany tried thorium in its pebble-bed reactor, and India built an entire nuclear strategy around its domestic thorium reserves, planning a three-stage cycle that would eventually rely on advanced heavy water reactors fueled with uranium-233 bred from thorium. Yet in every case, thorium stopped short of commercial deployment. The complexity of fuel handling, the need for an initial fissile inventory of uranium or plutonium, and the sheer momentum of the uranium-fueled reactor fleet kept thorium in the category of “promising but not delivered.”
Thorcon’s original vision was built on thorium’s promise. Its very name, short for “Thorium Concept,” signaled an intention to commercialize molten salt reactors running on a thorium cycle. Early designs envisioned dissolving thorium in molten fluoride salt, breeding uranium-233 in situ, and demonstrating the fuel’s long-touted advantages. But as the company moved from concept to trying to build an actual plant in Indonesia, pragmatism set in. For a first-of-a-kind power reactor, relying on thorium would mean untested chemistry, uncertain licensing pathways, and even greater risk.
Indonesia’s proposed demonstration plant is therefore designed to run on conventional low-enriched uranium fuel dissolved in molten salt, not thorium. Thorium remains a potential long-term option in the design, but the Indonesian reactor will take the easier, more familiar path to get the project off the ground. In other words, while Thorcon began as a bet on thorium, its first potential real-world deployment has been scaled back to uranium, underscoring how thorium continues to hover at the edge of nuclear power rather than forming its core.
Bent Flyvbjerg’s work on megaprojects should be a warning. He has shown repeatedly that nine out of ten large projects go over budget and over schedule, and nuclear projects are consistently among the very worst. The average nuclear build is more than 100% over budget and about a decade late. Add in the fact that this is a first-of-a-kind reactor by a company with no track record, in a country with no nuclear infrastructure, and the probability of delivering on time, on budget, and at promised cost of electricity falls close to zero. Even if the project is eventually completed, it will almost certainly take much longer and cost much more than advertised, and the benefits to Indonesia will not match the rhetoric.
The alternative paths are clearer and less risky. Indonesia sits on some of the world’s richest geothermal resources and has significant hydro potential. Solar costs continue to fall and the archipelago has ample land and rooftops for deployment. With investment in storage, interconnections, and grid modernization, these resources could supply reliable and cheap electricity without the risks of nuclear. International partnerships like the Just Energy Transition Partnership are already funneling billions into renewables and grid upgrades. Building out this system is not trivial, but it does not carry the weight of unproven technologies, uncertain regulation, and the specter of megaproject failure that Thorcon does.
Indonesia’s decision to approve Thorcon’s site evaluation is a political signal as much as a technical step. It reflects a desire to appear forward-looking and diversified in energy options. But unless the project is radically different from every other attempt to build nuclear in similar circumstances, it will become another cautionary tale. Years will be lost, billions may be sunk, and coal may remain in the system longer because resources are tied up in a nuclear dream.
A better bet would be to double down on renewables, expand storage, and build the transmission backbone to connect islands and balance supply. That path has its own challenges but rests on proven technologies already delivering results worldwide. Indonesia has made a bold gesture toward nuclear. The sober assessment is that it will not pay off.
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