As renewable energy continues to scale across Southeast Asia, the region’s power sector is under pressure to do more than just decarbonise. It must also remain reliable, affordable, and flexible. This balancing act is placing new demands on grid infrastructure and raising important questions about how power systems are designed, operated and valued. Meanwhile, with fewer coal plants are built, gas is evolving to act as a flexible backup, stepping in when wind and solar output falls short. In this context, flexibility, not just capacity, is becoming the defining characteristic of a resilient power system. This transition raises crucial questions for market and policy design. Flexible assets that operate fewer hours but provide essential stability must be valued differently. Without new mechanisms to reward their contribution, grid reliability may come under strain even as renewables expand.

Renewables with Flexibility - The “Best Friends Forever” (BFFs)

In a recent conversation with Nicolas Leong, Energy Business Director for North and Southeast Asia at Wärtsilä, it remains clear that flexibility, not just capacity, is the defining characteristic of a resilient ASEAN power system. Renewable energy and flexible generation technologies aren’t in conflict but complementary. Flexible gas engines and battery energy storage can adjust quickly to fluctuations in solar and wind output, providing real-time balancing that enables greater renewable integration. These solutions are also well-suited to Southeast Asia’s unique challenges. Extended cloud cover, monsoon seasons, and sudden shifts in demand all require a system that can ramp up or down at short notice. Rigid baseload plants alone cannot meet this need. But by pairing renewables with flexible gas and storage, grid operators can maintain system stability without compromising sustainability.

Hybrid Systems Make Sense for ASEAN

In many cases, hybrid systems that combine renewables, engine-based power, and energy storage offer the most practical path forward. They are modular, scalable, and able to grow with the grid’s needs. As system requirements evolve, these technologies can be optimised over time rather than locked into a single operating model. It’s not just about the technology itself, but the full value chain—starting with project development and continuing through long-term operations and performance optimisation. A strategic approach to hybrid deployment allows utilities and developers to match investments with evolving system conditions.

Preparing for the Fuel Transition

Even as natural gas supports today’s energy systems, the region must begin preparing for a shift to cleaner fuels like hydrogen and ammonia. Engine-based technologies that are compatible with future fuels offer an important bridge, supporting near-term flexibility while enabling a long-term transition. “We need to continue using gas while integrating renewable and prepare for future sustainable fuels,” he says. Developments such as the launch of the first Wärtsilä 100% hydrogen-ready power plants are early indicators of where the market is heading. As these technologies mature, they will play a larger role in decarbonising not just electricity generation, but also industrial energy use and transport.

A Defining Decade for ASEAN

The decisions made today, particularly on where to invest, which technologies to deploy, and how to value flexibility, will shape ASEAN’s power system for the next generation. Waiting for perfect solutions risks missing the critical window for action, stresses Leong. It is crucial to realise that building a flexible system doesn’t just future proof the grid but makes the energy transition more realistic and resilient. By recognising importance of flexibility, companies can achieve net zero through reliability and renewables at scale.

Watch the full interview below-