Hydrokinetic Energy in Northern Brazil: Evaluating the Impact of Diffusers on Turbine Efficiency in Rivers

Hydrokinetic energy represents a promising solution for decentralized electricity generation in remote regions of Northern Brazil, where access to conventional grids is limited and diesel-based systems dominate. This study evaluates the performance enhancement of diffuser-augmented hydrokinetic turbines deployed in the Itapeua and Jamari rivers using the Blade Element Momentum (BEM) method. Three diffuser geometries were investigated and compared with a bare turbine configuration. The results indicate that the incorporation of diffusers increases the power coefficient by approximately 38–52%, with diffuser D1 achieving the best performance, reaching a maximum Cp ≈ 0.89, compared to Cp ≈ 0.51 for the bare turbine. Correspondingly, the extracted mechanical power increases significantly, ranging from approximately 37.46 kW to 64.58 kW under average river velocities of 1.4–1.8 m/s. An economic assessment based on the levelized cost of energy (LCOE) indicates an average value of R$928/MWh, which is competitive with diesel-based generation in isolated Amazonian communities (typically R$1,200–R$1,800/MWh). Although simplified, the analysis demonstrates that diffuser-equipped hydrokinetic turbines can significantly improve both technical and economic performance, supporting their potential deployment in off-grid riverine systems.