The Solomon Islands could supply remote villages with electricity using small river turbines with a capacity of less than 5 kW. This is the conclusion reached by researchers from the University of Adelaide in Australia, who studied electrification pathways for the region. In their view, such installations could become a more affordable alternative to large hydropower plants and the expansion of centralized electricity grids in a country where only about 15% of the population currently has access to electricity, while in rural areas that figure is only about 3%.
The problem of the Solomon Islands is typical of many Pacific island states. The population is scattered across dozens of small islands, making the construction of transmission lines to remote settlements too expensive, while the existing energy system relies heavily on imported diesel fuel. Even in the capital, Honiara, electricity costs about $0.8 per kilowatt‑hour, one of the highest tariffs in the world. At the same time, relying on large hydropower plants does not solve the problem either. The construction of the 15 MW Tina River hydropower plant is estimated at about $240 million (about $16,000 per kilowatt of installed capacity), whereas the project has faced delays and cost overruns for several years. The researchers therefore decided to test whether a large number of small hydro turbines could be a more effective way to electrify rural areas.
With this aim in view, they used open global databases on rivers, digital elevation models, maps of existing electricity grids, and population density data. Since direct flow velocity measurements are lacking for most rivers in the Solomon Islands, the researchers calculated it using hydrodynamic models. Specifically, they applied the Manning‑Strickler formula, which estimates flow velocity based on channel characteristics, and the global WaterGAP model, which contains data on water resources and river runoff. This allowed them to estimate the potential energy that could be extracted from almost any river in the country. The data were then compared with the locations of settlements and existing energy infrastructure.
The calculations showed that about 35% of the country’s population lives within 500 meters of the nearest river, and about 65% within two kilometers. Only a quarter of the population lives close to existing power grids. To identify the most promising areas, the researchers assessed each province according to five criteria: population size, proximity to rivers, share of residents living near them, river energy potential, and distance from transmission lines. The most suitable province for small hydro turbines proved to be Malaita, where high population density is combined with low electrification rates and a large number of rivers.
As an example, the researchers examined in detail one of the rivers in this province which is called the Fiu River. A 750-kW hydropower plant costing about $15 million had previously been planned here, but the project was abandoned due to land disputes. Instead, the researchers propose using small hydrokinetic turbines that operate directly in the river flow without the need for a dam. According to their calculations, one such installation could generate about 1,600 kWh of electricity per year which is enough to provide one rural household with lighting, phone charging, a fan, a small refrigerator, and other basic household appliances.
The researchers emphasize that their analysis does not replace detailed surveys of specific rivers. However, it helps identify where small hydro turbines are likely to be most effective. In their view, such installations could become a more stable complement to the household solar systems already in use in the Solomon Islands.
