PT Geo Dipa Energi (Persero), Indonesia’s state-owned geothermal energy developer, recently engaged in high-level discussions with Toyo Engineering Corporation of Japan to deepen their partnership in geothermal resource development and to unlock new commercial opportunities from brine-based businesses
The meeting, which took place in late March 2026, involved senior representatives from both companies, including Toyo Engineering’s President and CEO Eiji Hosoi. It focused on practical ways to expand beyond traditional electricity generation by integrating advanced technologies that maximize the full potential of geothermal fluids.
According to a LinkedIn update shared by Rangga Hilman from Geo Dipa’s corporate communications team, the conversation was described as productive and insightful. Participants explored strengthening existing ties while identifying fresh avenues for value creation through brine utilization. Key discussion points included the application of closed-loop geothermal systems, the extraction of valuable minerals from geothermal brines, direct-use applications of geothermal heat, and enhanced subsurface monitoring techniques. These elements reflect a shared vision of transforming geothermal projects into multi-revenue-stream operations that deliver greater economic and environmental benefits.
This latest engagement builds directly on a Memorandum of Understanding (MOU) signed between Geo Dipa and Toyo Engineering back in September 2023 during the Indonesia International Geothermal Convention & Exhibition. That agreement initiated a joint study on full-scale or comprehensive geothermal utilization. The study encompasses not only power generation improvements but also innovative downstream applications such as closed-loop well designs, recovery of critical minerals like lithium, silica, and other elements from hot geothermal fluids, production of green hydrogen or ammonia, and optimization of existing geothermal fields for higher efficiency.
Toyo Engineering has positioned itself as a technology integrator in Indonesia’s geothermal sector. The company brings expertise in subsurface reservoir simulation, real-time monitoring systems (including its proprietary DX-PLANT® digital platform), and concepts like the “Geothermal Carbon Neutral Park.” This visionary model envisions geothermal sites as integrated hubs where electricity production coexists with the generation of clean fuels, mineral recovery, and direct heat applications. By combining these technologies, developers can reduce waste, lower carbon footprints, and create additional revenue streams that improve overall project economics.
Geo Dipa currently operates several geothermal facilities, most notably the Dieng and Patuha fields in Java. The Dieng field, located in Central Java, hosts an existing 55 MW unit, with plans for a second 55 MW unit (Dieng Unit 2) targeting commercial operations around April or May 2028. Similarly, Patuha Unit 2, also 55 MW, is under construction with peak activities expected in late 2026 and commissioning targeted for 2027. These expansion projects are central to Geo Dipa’s growth strategy, but the company is increasingly looking beyond megawatts to non-power businesses that can leverage the same geothermal resources.
The recent discussions with Toyo Engineering placed particular emphasis on applying closed-loop systems at the Dieng field. Unlike conventional geothermal plants that rely on flashing steam or binary cycles with potential scaling and reservoir management challenges, closed-loop technology circulates a working fluid through sealed underground loops to extract heat without direct contact with the reservoir in some designs. This approach can minimize water loss, reduce scaling or corrosion issues, avoid interference with nearby hot springs or protected areas, and enable development in locations previously considered marginal. It also facilitates better integration with brine processing for mineral extraction.
Brine-based businesses represent a rapidly emerging frontier in geothermal development worldwide, and Indonesia is well-positioned to lead in Southeast Asia given its vast geothermal resources—estimated as the second-largest globally after the United States. Geothermal brines, the hot, mineral-rich fluids produced alongside steam, often contain economically significant concentrations of lithium, a critical metal for electric vehicle (EV) batteries, energy storage systems, and other clean technologies. Extracting these minerals adds substantial value without compromising power output and can even improve plant performance by reducing scaling in surface equipment.
In parallel with the Toyo discussions, Geo Dipa has advanced its brine valorization efforts through a separate but complementary partnership. In March 2026, the company signed an agreement with California-based Lilac Solutions, supported by a grant from the U.S. Trade and Development Agency (USTDA). This initiative will establish Indonesia’s first pilot facility for lithium extraction from geothermal brine at the Dieng field. Lilac’s ion-exchange direct lithium extraction (DLE) technology is designed to recover high-grade lithium carbonate efficiently and with a lower environmental footprint compared to traditional evaporation pond methods.
The USTDA-funded pilot aims to demonstrate technical and commercial viability while connecting potential lithium output to U.S. and international off-takers. Geo Dipa’s leadership has highlighted the project as a strategic step toward supply chain resilience for critical minerals, supporting Indonesia’s broader goals in the energy transition and EV ecosystem. Estimates from various studies suggest that fields like Dieng could yield hundreds to thousands of tons of lithium annually if scaled successfully, potentially generating significant additional revenue while contributing to global decarbonization.
The alignment between the Toyo Engineering collaboration and the Lilac pilot is noteworthy. Both initiatives focus on Dieng as a proving ground. Closed-loop systems could help maintain or even enhance reservoir performance while enabling cleaner brine handling for mineral recovery. Enhanced subsurface monitoring, another topic in the recent meeting, would use advanced sensors (including fiber-optic distributed temperature sensing) and data analytics to optimize operations, predict reservoir behavior, and support safe, sustainable development.
Indonesia’s geothermal sector faces several well-known challenges: high upfront exploration and drilling risks, complex geology in volcanic terrains, grid connectivity limitations in some areas, and the need for supportive policies to attract investment. However, the country has made steady progress. Total installed geothermal capacity has grown over the years, with state-owned and private developers contributing to the national target of increasing renewable energy share in the power mix. Geo Dipa, as a specialized geothermal player under the Ministry of Finance, plays a pivotal role in developing fields that were historically managed by Pertamina Geothermal Energy or others.
Toyo Engineering’s involvement in Indonesia dates back many years through its local subsidiary IKPT (Indonesian Kajima-Pertamina or related joint ventures), which has delivered engineering, procurement, and construction (EPC) services for various geothermal plants. Recent examples include contributions to Patuha Unit 2, where Toshiba has supplied turbines and generators. This track record provides a solid foundation for expanding into technology-driven, value-added services rather than pure EPC.
Beyond the immediate Dieng and Patuha projects, the collaboration could extend to other Geo Dipa initiatives. The company has shown interest in the Jailolo geothermal prospect in North Maluku, with exploration drilling planned for mid-2026. Broader national efforts, such as Toyo’s earlier proposal for a Geothermal Master Plan in cooperation with Indonesia’s Ministry of Energy and Mineral Resources, aim to optimize resource allocation, identify new development opportunities, and integrate cutting-edge technologies across multiple fields. Such a master plan could incorporate closed-loop pilots, mineral recovery frameworks, and carbon-neutral park concepts to guide sustainable expansion toward 2030 and net-zero ambitions by 2060.
From a technical perspective, closed-loop geothermal systems offer several advantages. By isolating the working fluid, operators can maintain higher temperatures and pressures, achieve better thermal efficiency in some configurations, and reduce the risk of induced seismicity or reservoir depletion. When combined with binary cycle power generation, these systems can utilize lower-temperature resources that conventional flash plants might overlook. Toyo has partnered internationally, for instance with GreenFire Energy in the United States, to deploy advanced closed-loop solutions across the Asia-Pacific region, with Indonesia as a priority demonstration site.
Mineral extraction from brines adds another layer of complexity and opportunity. Geothermal fluids can contain not only lithium but also silica (useful for industrial applications), zinc, manganese, and other elements. Direct lithium extraction technologies like Lilac’s use selective ion-exchange materials that bind lithium ions while allowing the cleaned brine to be reinjected or further processed. This method is faster, uses less land and water, and produces fewer waste streams than solar evaporation. Successful pilots could pave the way for commercial-scale operations, potentially positioning Indonesia as a supplier of “green lithium” produced with renewable geothermal energy.
Direct-use applications discussed in the meeting represent yet another revenue pillar. Geothermal heat can support agriculture (greenhouses, soil heating), aquaculture, food processing, tourism (spas and resorts), and even district heating or cooling in suitable locations. In volcanic regions like Dieng, with its scenic landscapes and existing tourism, integrating direct-use infrastructure could boost local economies while diversifying Geo Dipa’s business portfolio away from pure power sales to PLN.
Enhanced subsurface monitoring is critical for all these initiatives. Real-time data from downhole sensors, combined with cloud-based analytics and artificial intelligence, enables operators to detect changes in reservoir pressure, temperature, and chemistry early. This supports proactive management, extends field life, and reduces operational risks—particularly important when introducing new technologies like closed loops or brine processing units that alter fluid dynamics.
The broader context of this collaboration reflects global trends in the energy transition. As countries race to secure supplies of critical minerals for batteries and renewables, geothermal brine is emerging as a sustainable, co-located resource. Unlike hard-rock lithium mining or traditional brine evaporation in arid regions, geothermal-derived lithium can leverage existing energy infrastructure and benefit from low-carbon power. For Indonesia, which aims to become a major player in the EV battery value chain through its nickel resources, adding lithium from geothermal sources creates synergies across the minerals and energy sectors.
Economically, brine-based businesses can improve project internal rates of return (IRR) by generating non-power income that offsets high capital costs. Environmentally, they promote a circular approach: heat is used for power, minerals are recovered, residual heat supports direct uses, and fluids are reinjected sustainably. This aligns with Indonesia’s commitment to reducing greenhouse gas emissions and achieving net-zero electricity by mid-century.
Looking ahead, both Geo Dipa and Toyo Engineering have expressed optimism about advancing the collaboration in the coming months. Next steps may include detailed feasibility studies, pilot testing of closed-loop configurations at Dieng, integration planning with the Lilac lithium pilot, and exploration of green hydrogen production using surplus geothermal electricity or heat. Geo Dipa’s dual strategy—expanding conventional power capacity while developing non-power businesses—positions it to capture value across the entire geothermal value chain.
Challenges remain, including securing additional financing, navigating regulatory frameworks for mineral extraction alongside power generation, ensuring community acceptance, and building local technical capacity. However, partnerships with experienced international players like Toyo Engineering and Lilac Solutions bring not only technology but also access to global expertise, financing networks, and markets.
In summary, the recent discussions between PT Geo Dipa Energi and Toyo Engineering Corporation mark a significant step toward modernizing Indonesia’s geothermal industry. By focusing on closed-loop systems, brine mineral recovery, direct uses, and advanced monitoring, the partnership aims to transform geothermal fields from single-purpose power plants into versatile, high-value energy and resource hubs. With Dieng as a focal point and national ambitions providing tailwinds, this collaboration could serve as a model for sustainable geothermal development not only in Indonesia but across the geothermal-rich regions of the world.
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