More than 740 million people live on islands that are well suited for renewable energy deployment. Yet many island nations remain highly vulnerable to climate change and dependent on costly fossil fuels, creating persistent macroeconomic pressures and reducing competitiveness.
A comprehensive review shows that highly renewable energy pathways are technically feasible and economically viable on islands. Nevertheless, research gaps remain. Many tropical islands are underrepresented, studies of fully renewable systems are limited, and multi-sector integration beyond the power sector is rare. Technology and resource assessments often overlook biomass sustainability, hydrogen, synthetic e-fuels, and ocean or geothermal energy, while environmental and social impacts are underexplored. Methodologies vary, and transition pathways beyond 60% renewable energy supply, including interconnection and alternative energy carriers, remain scarcely examined.
Against this backdrop, a series of studies from LUT University and its collaborators highlight pathways for islands across the Caribbean, Indian Ocean, and Pacific to achieve carbon neutrality by 2050. These studies emphasize high electrification, rapid renewable energy adoption, and the integration of advanced ocean-based energy technologies, including wave power, offshore wind power, and floating offshore solar PV systems. Together, these solutions provide a blueprint for a sustainable, secure, and low-carbon future for island communities.
Solutions for tropical islands worldwide
Steering highly renewable energy systems in tropical islands is possible, and variable energy resources, especially solar PV, will spearhead the transition. The anticipated solar energy momentum in tropical islands is driven by excellent resource conditions and rapidly improving economic competitiveness. Solar PV dominates the energy-industry landscape, accounting for 67-94% of total electricity generation, with wind contributing 6-30%, across the Caribbean. Comparable results are reported for the cases of Hawaiʻi, Indonesia, New Zealand, Maldives, Sri Lanka, Seychelles, Puerto Rico, and the Philippines.
Space limitations do not preclude tropical islands from achieving energy self-sufficiency and carbon neutrality. Offshore technologies provide a scalable pathway to a sustainable energy future while simultaneously strengthening the blue economy. A diversified portfolio of offshore renewable energy technologies, including floating offshore solar PV, offshore wind turbines, and wave power, may become essential for deep defossilisation of archipelago countries, as demonstrated by the cases of the Maldives, Hawaiʻi, and Seychelles. Wave power, while limited in the Maldives and Seychelles and showing higher potential in Moloka'i and Hawai'i, consistently enhances the diversity of island energy systems and complements solar PV- and wind power-dominated generation.
In New Zealand, as an example of a non-tropical island nation, wave power is less of a focus in cost-optimised energy system analyses, as the energy system can largely transition from a hydropower-centric to a solar PV-centric supply. Wave power could further diversify the energy mix at marginal additional cost to harvest one of the best wave energy resources in the world, with an excellent solar and wave energy resource complementarity over the year. Floating offshore solar PV has also been shown to be competitive with ocean thermal energy conversion in another study on the Maldives.
Solar-to-X Economy not only for land-locked countries
Solar-dominated, multigeneration energy-industry systems in tropical islands can effectively be described as a Solar-to-X Economy, in which low-cost solar PV electricity serves as the basis for a vibrant e-fuels, e-chemicals, and e-material industry. Low-cost renewable electricity and e-hydrogen form the cornerstone of a carbon-neutral energy system in tropical islands, embedded within a power-to-X framework. The power-to-X approach applied across the reported studies enables deep defossilization of hard-to-abate sectors, benefiting from flexibility opportunities. Although tropical islands could achieve energy self-sufficiency, studies often focus on e-fuel imports due to land constraints, whereas e-hydrogen imports are avoided owing to technical challenges and high hydrogen transport costs. e-Fuel imports can play a key role in cost-effective renewable energy systems across islands. In the Caribbean, they reduce land use and system costs by 7–16% while lowering fuel supply and electricity trade by up to 70% by 2050. Similarly, in Hawaiʻi, a 100% renewable energy system with e-fuel imports represents the lowest-cost scenario and can be achieved without offshore technologies. In the Maldives, system costs are projected to rise from €105.7 per MWh in 2017 to €120.3 per MWh in 2030, before falling to €77.6 per MWh in 2050 with imported CO2-neutral e-fuels for transport.
Early adoption of solar PV, wind power, and batteries in the Caribbean can cut emissions and reduce transition costs, despite accelerated approaches increasing short-term costs by 3–12%. Caribbean grid interconnections further lower system costs by 11%, reduce the levelised cost of electricity by 14%, cut CO2 emissions by 4%, and make renewable pathways 7–24% cheaper than fossil alternatives. In Indonesia, a highly renewable energy pathway lowers annualised system costs by 42% and achieves carbon neutrality by 2050, with electricity priced at €37 ($43.4) per MWh, roughly 10% cheaper than a moderately renewable scenario and 57% cheaper than a coal-dominated system. Similarly, in Sri Lanka, highly renewable energy pathways incur substantially lower cumulative annual transition costs to 2050, with less renewable or conventional alternatives exceeding costs by 41–51%. In this regard, updated cost assumptions for energy system analyses are an important element for relevant insights.
Flexibility as a key towards a secure and cost-effective future
Security of supply is often highlighted as a concern in systems dominated by variable renewable energy resources, particularly solar PV. Flexibility in these energy systems is provided by storage technologies, including batteries for short-term variability, pumped hydro energy storage for short- to mid-term flexibility, and gas storage for seasonal variability. Gas storage, which for islands may take the form of buoyancy energy storage systems, serves a dual purpose: balancing the power system and acting as a buffer for e-fuel production. Additional flexibility is provided by demand response, smart charging, and vehicle-to-grid technologies. In addition to storage and demand response, also power grids, diverse power-to-X conversion, and limited curtailment form a portfolio of flexibility options. These technologies are essential for ensuring the reliability of a resilient Solar-to-X Economy.
Adopting renewable energy can substantially lower energy system costs in tropical islands. Solar PV-battery hybrids emerge as particularly cost-effective, and integrating solar PV-driven solutions within a Solar-to-X Economy delivers both environmental and economic benefits. Key elements for defossilization include low-cost renewable electricity, energy storage, electrification, e-fuel imports, sector coupling and grid interconnections. Together, these measures enable resilient, cost-effective, and sustainable energy systems. Power-to-X technologies play a pivotal role in supporting carbon neutrality, energy security, and stimulating economic growth across island nations.
Authors: Ayobami Solomon Oyewo, Ashish Gulagi, Gabriel Lopez, Dominik Keiner, and Christian Breyer
This article is part of a monthly column by LUT University.
Research at LUT University encompasses various analyses related to power, heat, transport, desalination, industry, and negative CO2 emission options. Power-to-X research is a core topic at the university, integrated into the focus areas of Planetary Resources, Business and Society, Digital Revolution, and Energy Transition. Solar energy plays a key role in all research aspects.
The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.
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