As the global energy demand grows, traditional sources are under strain. However, ocean energy produced from currents has emerged as a viable candidate for clean energy.
Oceans cover around 70% of the planet’s surface, meaning ocean energy is highly exploitable for clean energy from renewable resources such as currents and waves.
However, marine energy development is still in its early stages compared to wind and solar power. One challenge is identifying the most feasible and economically viable locations for ocean current energy projects.
While many studies have focused on regional ocean current energy resource assessment, until now, a global evaluation based on actual data has been lacking.
Using more than 30 years of measured data from NOAA’s Global Drifter Program (GDP), a unique study from the College of Engineering and Computer Science at Florida Atlantic University provides the most comprehensive global assessment of ocean current energy to date.
Florida and South African coasts emerge as top ocean energy producing locations
The researchers explored the potential of capturing kinetic energy from ocean currents, focusing on power density estimation and its variation over time and location.
The results revealed that waters off Florida’s East coast and South Africa consistently exhibited high power densities, making them ideal for generating ocean energy.
Specifically, these regions showed power densities above 2,500 watts per square metre, a value 2.5 times more energy dense than an ‘excellent’ wind energy resource.
The relatively shallow waters further enhance their suitability for extracting energy using ocean current turbines. In contrast, regions like Japan and parts of South America did not show similar power densities at these depths.
“Our study revealed that about 75% of the total high-power density areas, covering around 490,000 square kilometres of the ocean, have energy levels between 500 and 1,000 watts per square metre,” explained Mahsan Sadoughipour, PhD, first author and graduate research assistant in the College of Engineering and Computer Science.
“This suggests there’s a lot of potential for harvesting energy from ocean currents, especially in regions where power densities are moderate yet significant for sustainable energy production.”
Power density estimates cement the potential of production regions
High power densities, more than 2,000 watts per square metre, are found off the Southeast coast of the U.S. from Florida to North Carolina and along the Eastern and Southeastern coasts of Africa (Somalia, Kenya, Tanzania, South Africa and Madagascar).
Lower power densities are seen in the Eastern Pacific (Japan, Vietnam and the Philippines), Northern South America (Brazil and French Guiana), and the Eastern coast of Australia.
Another key finding from the study was the accuracy of power density estimates. In North America and Japan, the calculations were highly reliable, providing confidence in ocean energy potential predictions.
Additionally, comparisons with existing studies have confirmed the reliability of the findings in these regions, as the power density estimates closely matched measurements obtained through other measurement methods.
However, areas like South Africa and parts of South America, particularly off northern Brazil and French Guiana, were harder to assess due to limited data or highly variable water conditions.
Yufei Tang, PhD, who co-authored the study, stated: “Regions like Brazil and South Africa have limited data available, which affect the accuracy of energy predictions, making it harder to fully assess their potential for energy extraction.
“Expanding data collection will refine our understanding and unlock the full energy potential.”
Challenges in deep water locations
Findings also show that areas like South Africa and Japan, which have high power densities, present more challenges due to deeper waters and complex flow patterns.
Deep-water areas (1,000 metres or more) make energy extraction more challenging.
James VanZwieten, PhD, another co-author, said: “The relationship between depth and power density is crucial for turbine placement and design.
“Strong ocean currents are located near the sea surface, where the total water depth typically ranges from 250 metres to more than 3,000 metres.
“This presents significant challenges, as turbines would require advanced mooring systems to keep them stable and operational.
“The increased depth also raises concerns about the cost and complexity of installation and maintenance, making it essential to develop specialised technologies for these challenging environments.”
The role of seasons in ocean energy production
Seasonal variations also play a significant role in energy availability. In warmer months for the Northern hemisphere (June to August), higher power densities are observed in regions like Florida, Japan and Northern Brazil, aligning with increased energy demand during these months.
Similarly, the highest power densities in South Africa occur during their warmer months (December to February).
These seasonal patterns indicate that ocean current energy could align well with periods of higher electricity demand associated with increased air conditioning usage, making it a potentially reliable source of renewable energy.
Findings from this study highlight the need to consider these variables carefully, and the provided energy characteristics will help ensure that ocean current energy can be efficiently integrated into the broader renewable energy landscape.
