Techno-Economic Analysis of Axial-Flow Current Turbines Applied to the US Virgin Islands

The Small Island Developing States (SIDS) face a myriad of energy challenges due to their dependence on imported fossil fuels and increased rates of natural disasters, resulting in high electricity costs and grid instability. Marine current energy continues to be an emerging energy technology because of high installation and maintenance costs; however, the large resource availability makes it a promising resource for islands. This study is a techno-economic evaluation of a novel bridge-supported marine current energy system designed for shallow-water deployment, using the U.S. Virgin Islands as a case study. A bridge support structure is proposed that will allow for ease of installation and maintenance within local systems. The National Renewable Energy Laboratory (NREL) Reference Model 4 was used as the framework for the technical design and cost estimates and was adjusted based on economies-of-scale relationships. We develop an estimate for the levelized cost of energy (LCOE) for installations for a range of deployments and perform sensitivity analysis over current velocity correction factors, turbine size, and interest rate. The results indicate that a three-unit installation for this case study will achieve an LCOE of $1.13/kWh, while 100-unit deployments can reduce the LCOE to $0.31/kWh. The technology becomes economically competitive with the present electricity cost in the U.S. Virgin Islands—$0.42/kWh—at an installed capacity of approximately 10 MW. These findings demonstrate the potential of bridge-supported marine current energy systems to strengthen energy security and support the renewable energy transition in the Caribbean and other Small Island Developing States.