Just 2% of tidal and offshore solar energy could make a dent in carbon dioxide emissions

Harnessing just 2% of the energy potential from tidal and offshore solar sources could make a significant dent in global CO₂ emissions, new research has found.

Researchers at the Universities of Strathclyde and Maine examined more than 660 assessments of offshore renewable energy (ORE) potential in more than 3,000 locations worldwide. They found that tidal and solar consistently had more energy to offer than other sources such as wind and wave, but were the subject of far less research, and consequently, remained largely untapped.

Offshore solar energy, in particular, was found to be more reliable and less variable than other sources, making it ideal for energy mixes. Despite their lower theoretical potential, wind and wave energy accounted for three-quarters of the assessments examined by the researchers.

The research is published in the journal Renewable and Sustainable Energy Reviews.

Small percentage

The study concluded that even a small percentage of tidal and offshore energy could make a notable contribution to CO₂ reduction and to meeting the United Nations’ Sustainable Development Goals (SDGs) on Climate Action and Affordable and Clean Energy.

Assuming global emissions are equivalent to 2019 levels, an additional 2% of combined tidal and solar resources would remove 0.299 gigatons per year. At this rate, net neutrality would be reached in 68 years.

The research standardized the energy estimates into a single unit of kilowatts per square meter (kW/m²). It is believed to be the first study to give a comprehensive assessment of global offshore renewable energy sources.

Significant opportunities

James Spalding, a Ph.D. student in Strathclyde’s Department of Civil and Environmental Engineering and lead researcher on the project, said, “This is the first time such a broad and interdisciplinary comparison has been possible. By standardizing data across resource types and locations, we have identified significant opportunities for clean energy that have so far been overlooked.

“Our research highlights the value of assessing where the greatest resource potential exists, rather than limiting development to what is currently most technologically mature. ORE potential is estimated to be up to double the global electricity demand. It has also been shown to improve access to clean energy for many nations that have a smaller GDP and are dependent on fossil fuel imports for electricity supply.”

Projections indicate that the energy sector must reach at least 60% of global energy generated by renewables by 2030, and 80% by 2050, if net-neutral CO₂ emissions are to be achieved. However, the global energy supply in 2019 included only 23% renewable energy, with less than 1% coming from ORE sources. More than half of the ocean energy capacity came from projects located in Europe and was produced by offshore wind, tidal current, and wave energy converters.

The researchers assessed data for the study in six global regions, which they defined as the eastern North Atlantic; Mediterranean; eastern North Pacific; coastal Asia; western North Atlantic, and southern hemisphere. Six ORE sources were assessed: offshore wind; wave; offshore solar; ocean currents; tidal range and ocean thermal energy conversion (OTEC).