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The SEA region did not have to look far back for a lesson. Geopolitical tensions and the risk of disruption to the world’s critical energy supply routes in recent times have exposed a truth many countries had overlooked; depending too heavily on any single energy source or supply route is a strategic vulnerability. Although these events primarily involved fossil fuels, the deeper lesson is universal — every economy needs security and continuity in its energy supply.

The Region’s Answer and the Coming New Challenge

For Southeast Asia, one answer has been to reduce dependence on imported energy by developing sources within the region, raising the share of renewable energy, not only with Net Zero ambitions but also due to new demands from the rapid expansion of advanced technology investments such as Data Centers, leading to unavoidable limitations on the power grid. Renewable energy sources generate electricity intermittently. Solar panels produce power only during daylight hours, wind turbines only when the wind blows, and hydropower output declines in the dry season. The hours of peak generation rarely align with the hours when people actually need power. The more a power system relies on renewables, the greater the need to store electricity for the periods when generation falls short.

Energy Storage: The Heart of Tomorrow’s Power Systems

When the topic of energy storage is discussed the first answer that most people think of is battery energy storage — a technology that plays an important role and performs well up to a certain extent. But when the challenge is energy storage at the national utilities scale with the demand to discharge large volumes of electricity over extended periods, battery energy storage faces technical shortcomings and high investment costs that make the technology uneconomical. It is this gap that has turned global attention back to another form of energy storage.

The technology in question is no new invention; the world has been using it for more than a century. Pumped Storage Hydropower (PSH) operates on a simple principle: surplus electricity is used to pump water up to an upper reservoir, and the water is released back down to generate power when the system needs it. Its strengths — storage at the scale required by the national power grid, and an operating life spanning decades — are precisely what batteries cannot match. In simple terms, we can consider PSH as a “Green Mega-Power Bank”. The IEA’s Hydropower Special Market Report confirms this direction, projecting that even as battery storage capacity expands more than tenfold by 2030, PSH storage capacity will remain significantly higher, and that PSH will account for 30% of net new hydropower capacity worldwide.

Two Paths to PSH

The next question is: where will this storage capacity come from?

There is more than one route to expanding PSH capacity. One approach drawing growing interest is adding pumping capability to existing hydropower plants, or PSH Retrofitting, which leverages dams, reservoirs, and transmission networks already in place — allowing faster development and earlier tangible results. At the same time, developing new projects in high-potential sites is another path that serves long-term demand. According to the IEA, beyond the storage capacity to be added by newly developed projects, a further 3.3 million megawatt-hours worldwide is set to come from adding pumping capability to existing plants.

These pathways reflect the bigger picture of the energy transition. Mr. David Van Dau, Chief Executive Officer of PSG Corporation Public Company Limited (PSGC), shared his perspective: “A sustainable energy transition does not come from adding renewable energy alone. It requires a system that balances security, sustainability, and long-term growth all at once. Energy storage technologies such as pumped storage hydropower are therefore a critical component — reinforcing the stability of the power system and opening the way for renewable energy to grow to its full potential.”

Lao PDR: Infrastructure Ready to Build On

Viewed through the lens of ASEAN, one country stands out: the Lao PDR. It is currently the region’s largest hydropower electricity exporter, and the Lao government aims to export a total of 20 gigawatts by 2030. That status reflects the country’s extensive base of operating hydropower plants and reservoirs, along with high-potential sites for new development — the essential building blocks that PSH requires. For PSGC, which already operates within the region’s energy supply chain, the expansion into PSH builds on the market understanding the company has developed. PSGC has signed a Memorandum of Understanding (MOU) with Électricité du Laos (EDL) to study the feasibility of upgrading existing hydropower plants with strong potential into pumped storage systems, strengthening energy security and serving electricity demand within the Lao PDR — and, where capacity allows, exporting power to countries across the region through EDL’s transmission network. The company has also signed an MOU with the Government of the Lao PDR to study numerous sites across the country with the potential for long-term PSH development, in parallel with its work with EDL.

A Long Game Built on Foundations Laid Today

Developing a PSH project is a strategic medium-term to long-term investment, requiring comprehensive feasibility studies conducted in stages — from preliminary potential assessments through in-depth technical and economic analysis — before a final investment decision is made. PSGC therefore views this undertaking as laying medium to long-term foundations rather than something to be tracked quarter by quarter. The IEA likewise notes that the key challenge for PSH lies in its nature as large-scale, capital-intensive infrastructure; working closely with governments and infrastructure owners from the outset is therefore a critical factor in keeping projects moving forward on solid ground.

All of this reflects PSGC’s view of where power systems are headed. The energy transition of the coming decade will not be measured by the volume of clean energy generated alone, but by the ability to store that energy for the moments the system needs it. For a region as rich in water resources as ASEAN, PSH may well be a key piece of the puzzle in making the power system more secure and more flexible — and that is the direction PSGC has chosen to prepare for, starting today.