Across the world, island communities are at an energy crossroads. Historically reliant on costly, carbon-heavy diesel generators, these often-isolated regions are confronting the stark reality of maintaining a status quo that is becoming increasingly financially and environmentally untenable.

The challenge of securing reliable electricity in remote locations has never been about a lack of willingness. Diesel generators offered a simple solution for decades: they are quick to install and easy to maintain.

But at what cost? Imported diesel exposes islands to volatile fuel prices, logistical headaches and harmful emissions. Energy insecurity is inherent in this system. And as climatic change drives more intensive weather events, and supply chains become more fragile, that insecurity grows.

Distributed and local grid-connected renewable energy is part of the solution. Caribbean islands are rapidly deploying on and off-grid solar alongside onshore wind and battery energy projects. But these projects are vulnerable to extreme weather. In addition, insurance costs and risk transfer can pose challenges in securing project investment.

The complementary solution to domestic renewable deployment for islands is of course greater interconnectivity to larger islands or countries with more diverse and resilient energy grids.

Blueprint for change in Belize
Belize offers a powerful example. The islands of San Pedro and Caye Caulker, just off the mainland coast, have long depended on local diesel generation to power homes, businesses and their vital tourism sectors. But a new project is changing that reality and showing what is possible. With OMSI installing a 15 km, 34.5 kV submarine cable connection to Belize’s mainland grid – where hydroelectric and biomass sources make up around 70% of generation – the islands are shifting onto a cleaner and more stable footing.

From our experience supporting this effort, the benefits of grid integration are both immediate and multifaceted. Energy costs fall. Reliability improves. Diesel imports diminish, along with their associated risks to marine ecosystems. And perhaps most importantly, the islands increase green energy utilisation and build greater resilience against future climate shocks by tapping into that diversified and lower-carbon power supply.

Growing global movement
Belize is not alone. Around the world, other island communities are taking their own paths towards energy independence and a greener energy mix.

In the Philippines, the completion of a 230 kV submarine cable between Cebu and Bohol has significantly bolstered Bohol’s energy stability. This infrastructure now enables the island to draw on more reliable power sources from the Visayas grid, supporting its growing economy and reducing dependence on diesel.

Greece has taken a similar approach with its multi-phase Cyclades Interconnection project, which is progressively linking remote islands such as Milos and Serifos to the national grid.

By replacing outdated island-based generation with power imported from the mainland, these projects are cutting emissions, enhancing grid reliability and improving power quality for local residents.

Meanwhile, in Brazil, Santa Catarina Island has been connected to the mainland via a 230 kV submarine cable. The interconnection has improved grid stability for the island and reduced the risks associated with isolated energy systems – which is particularly important as demand grows across residential and tourism sectors.

These examples highlight a global trend: island communities are moving from vulnerability to leadership and security in the clean energy transition.

Connecting islands to larger, cleaner grids – or building resilient renewable systems where connection is impractical – represents some of the clearest, most immediate wins in the global energy transition.

Barriers to overcome
While the direction of travel is clear, the journey remains challenging.

First, there’s the question of cost. Submarine cable supply and installations demand significant upfront investment and require extensive feasibility studies. For many islands, external financing or government support is critical to overcome this barrier.

Second, technical resilience is key. Infrastructure must be engineered to survive the harshest marine environments and designed with redundancy to keep power flowing during extreme events. Installation credibility needs to be established with the installation of the submarine cable performed according to international standards, but for the level of a local community.

Third, every island is unique. Solutions must be tailored to local conditions, from seabed geography and weather contingencies to energy demand patterns. There is no one-size-fits-all approach.

Finally, there’s a human dimension. Successful projects don’t just install hardware; they build trust, skills and local capacity to operate and maintain systems for the long term for the local community.

The opportunity ahead
Connecting islands to larger, cleaner grids – or building resilient renewable systems where connection is impractical – represents some of the clearest, most immediate wins in the global energy transition.

It’s an opportunity not just to cut emissions, but to transform the foundations of local economies: lowering energy costs, improving health outcomes, attracting sustainable investment and strengthening resilience in the face of a changing climate.

From our own experience in delivering subsea cable infrastructure, we believe that collaborative, out-of-the-box thinking, locally-informed projects can and will be the catalyst for change. It requires coordinated action and support from governments, businesses, financiers and island communities – not just for the goal of energy security, but for a broader vision of economic and environmental renewal.

And let’s be clear, the technology exists. The cost is affordable. The need is obvious. We must ensure grids are turned into energy bridges, ensure that island communities are no longer the last to benefit from the clean energy transition revolution.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute.

• Further reading: ‘Small islands with big energy ambitions’. Although they are responsible for a tiny fraction of the world’s total emissions, decarbonising small island states is still important for a just global energy transition, and often provides significant benefits for inhabitants. Charlie Bush reports on recent energy transition initiatives in often-overlooked areas of the world.
• Find out how the Caribbean islands are seeking to harness plentiful solar power in ambitious projects aimed at cutting electricity costs and boosting energy independence.