However, marine renewable 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, a global evaluation based on actual data has been lacking - until now.
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. And there's great news for Southeast Florida.
Researchers explored the potential of capturing kinetic energy from ocean currents, focusing on power density estimation and its variation over time and location. The GDP includes about 1,250 satellite-tracked buoys that measure ocean currents and their positions. For this study, researchers used more than 43 million data points from March 1988 to September 2021.
Results, published in the journal Renewable Energy, reveal that the waters off Florida's East coast and South Africa consistently exhibited high power densities, making them ideal for generating electricity from ocean currents. Specifically, these regions showed power densities above 2,500 watts per square meter, a value 2.5 times more energy dense than an "excellent" wind energy resource. The relatively shallow waters - about 300 meters deep - 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 kilometers of the ocean, have energy levels between 500 and 1,000 watts per square meter. 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," said Mahsan Sadoughipour, Ph.D., first author and graduate research assistant in the College of Engineering and Computer Science. "Our study also provides insights into the factors that can influence the accuracy of energy generation estimates such as environmental conditions and measurement methods."
High power densities, more than 2,000 watts per square meter, 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 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 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.
"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," said Yufei Tang, Ph.D., co-author and an associate professor, FAU Department of Electrical Engineering and Computer Science, director of the FPL Center for Intelligent Energy Technologies (InETech) (fau.edu/engineering/research/fpl-center-intelligent-energy-technologies/), and a fellow of the FAU Institute for Sensing and Embedded Network Systems Engineering (I-SENSE). "Expanding data collection will refine our understanding and unlock the full energy potential. For example, region-specific studies using acoustic Doppler current profilers could better estimate energy production for submerged turbines."
Findings also show areas like South Africa and Japan, while having high power densities, present more challenges due to deeper waters and complex flow patterns. Deep-water areas (1,000 meters or more) make energy extraction more challenging.
"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 meters to more than 3,000 meters," said James H. VanZwieten Jr., Ph.D., co-author and an assistant professor in the FAU Department of Ocean and Mechanical Engineering. "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 specialized technologies for these challenging environments."
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, highest power densities in South Africa occurs 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.
"Accurate estimates of ocean current energy rely on critical factors such as data density, data type and flow variability," said Stella Batalama, Ph.D., dean of the College of Engineering and Computer Science. "Findings from this study highlight the need to carefully consider these variables, and the provided energy characteristics will help ensuring that ocean current energy can be efficiently integrated into the broader renewable energy landscape."
This work was supported in part by the National Science Foundation, the U.S. Department of Energy and the FPL InETech at FAU.
"This groundbreaking research further solidifies Southeast Florida as one of the premier locations for harnessing the power of ocean currents," said Gabriel Alsenas, director of FAU's Southeast National Marine Renewable Energy Center. "At SNMREC, we are proud to be at the forefront of domestic energy innovation, driving progress toward a more resilient future. With our unique access to an abundant ocean current, we are leading the way in incubating cutting-edge technologies that will increase our regional energy security and national energy dominance."
Research Report:Drifter-based global ocean current energy resource assessment
Related Links
Southeast National Marine Renewable Energy Center
Powering The World in the 21st Century at Energy-Daily.com
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