The third workshop of GTI’s Empowering Islands Programme turned attention to two resources islands are uniquely placed to exploit: the heat beneath their feet, and the waste they already produce on-site. For territories defined by limited land, high transport costs, and near-total dependence on imported fuel, geothermal and bioenergy offer something solar and wind alone can’t: steady, dispatchable power that doesn’t need a ship to deliver it.
The ground has more to offer than most islands assume
Island geology is often treated as a barrier to geothermal, too costly, too uncertain, only viable on the right kind of volcanic terrain. The workshop challenged that. What matters is heat, not necessarily an active volcano, and geothermal’s footprint is famously small, a critical advantage where every hectare is contested between housing, tourism, and energy infrastructure. The technology also solves problems specific to island life: unstable diesel supply chains that cause blackouts, and health infrastructure that suffers when the power does. A shallow geothermal cooling system installed on a dry Canary Island this summer now keeps a hospital running on wells just 60 metres deep, evidence that resilience, not just megawatts, is the real payoff for remote communities. In the Azores, one plant has supplied over a quarter of an island’s baseload power for nearly a decade, cutting fossil fuel imports and thousands of tonnes of emissions in the process, a working template for volcanic islands anywhere.
Waste, reframed as a resource islands don’t have to import
Bioenergy solves a problem every island recognises: waste has nowhere to go. Without a mainland to export it to, food scraps, agricultural residue, and sugarcane byproduct pile up, causing contamination and threatening the natural beauty that draws tourists in the first place. The workshop’s case studies showed how that same waste stream becomes a local, decentralised energy source instead, with no shipping, storage, or import dependency required. A sugar-producing Indian Ocean island now runs a meaningful share of its national grid on bagasse; a neighbouring island draws close to half its electricity from local residues. At the smallest end of the scale, a plug-and-play digester on a 150-person Irish island converts daily food waste into cooking gas for its restaurant and homes, cutting both emissions and reliance on the mainland ferry for waste disposal, while doubling as a point of cultural pride for the island’s language and heritage.
Across both technologies, the workshop kept returning to what islands need most: independence from fragile supply chains, resilience against blackouts and disruption, and solutions sized to fit limited land and small populations. Neither geothermal nor bioenergy works alone, and neither succeeds without the patient early-stage work of understanding the resource and reducing risk before committing capital. But the message for islands was reassuring: these aren’t emerging technologies waiting for the future. They’re mature, proven, island-suited, and already reducing fuel imports, strengthening health infrastructure, and keeping economic and environmental benefits exactly where they belong, on the island itself.
