Flexible Green Fuels: The Missing Piece in Island Energy Transition

Introduction: The Unique Challenges Facing Island Power Systems

Island power systems face structural constraints that are fundamentally different from those of mainland grids. Many operate in isolation, with limited generation diversity. Due to their remote geographic locations and high logistics costs, electricity supply is highly vulnerable to fuel price volatility. Their exposure to natural disasters makes reliability critical, yet system scale remains constrained.

As renewable penetration increases, island energy systems are seeking viable pathways to reduce carbon intensity while maintaining security of supply.

In regions such as the Pacific Islands and the Caribbean, diesel generation remains the primary source of electricity.

Traditional Paradigm: Baseload First, Renewables Second

Historically, energy planning for island systems has followed a clear logic:

1. Secure stable baseload generation
2. Integrate variable renewable energy such as solar and wind
3. Use battery storage to manage fluctuations

Under historical cost structures, this framework was rational. Fossil-fuel generation provided stability, while renewables acted as a supplementary resource that could reduce overall electricity costs to some extent.

However, with ongoing technological progress, this assumption is gradually being challenged.

New Evidence: Flexibility May Matter More Than Stability

Recent research using HOMER Pro to model a Pacific island grid indicates that the optimal configuration may not require conventional baseload generation at all.

Optimal configuration:

Solar PV + Battery Storage + 4% Biomass Generation for Peak Shaving

The most striking finding is not the presence of biomass itself, but the scale of its contribution, only 4%.

This small share can deliver:

• A reduction of 97 MW in required PV capacity
• A reduction of 143 MWh in storage capacity
• Upfront investment savings of $141 million

Compared with diesel-based systems, the levelized cost of electricity can decrease by up to 60.8%.Compared with a pure solar-plus-battery configuration, LCOE can fall by 45%.

Notably, these results occur even in an island country with only moderate solar resources.

Why Can Such a Small Share Reshape the Entire System?

In isolated grids, system sizing is driven by extreme conditions rather than average performance.

Peak demand periods, low renewable output intervals, and reserve requirements push planners toward oversizing generation and storage assets. Batteries, in particular, must be sized to withstand these critical scenarios.

Introducing a small amount of dispatchable green fuel changes this dynamic.

By covering infrequent peak demand events, flexible biomass generation reduces the need to overbuild renewable capacity and storage infrastructure, thereby significantly lowering total capital investment.

This phenomenon suggests that the perspective of energy planning itself may need to shift.

In the future, the central challenge for energy systems may no longer be baseload supply, but how to enhance overall reliability, flexibility, and resilience.

Ammonia as a Flexible Green Fuel Is Entering the Spotlight

Ammonia possesses several characteristics relevant to modern energy systems:

1. High volumetric energy density
2. Established global transport and storage infrastructure
3. Combustion capability in adapted engines and turbines
4. Potential to be converted back into hydrogen through cracking

Unlike purely electrical storage solutions, ammonia enables long-duration and even seasonal storage of renewable energy in chemical form. It can be produced from green hydrogen using renewable power, transported globally, and utilized when needed.

In island grids, ammonia does not need to replace baseload generation to deliver value. Even limited deployment as a peak fuel can generate systemic benefits by reducing the need for oversized renewable and storage capacity.

Conclusion

As technologies continue to evolve, flexible green fuels may shift from being a marginal component of power systems to becoming a structural enabler of practical, high-renewable grids.

They may well represent the key to unlocking the next stage of the energy transition.