1.2 Global Ocean Energy Distribution and Availability

Ocean energy is a vast, untapped resource with huge potential. Different types like tides, waves, and thermal gradients are spread unevenly across the globe. Understanding where and why these energy sources are concentrated is key to harnessing their power.

Factors like geography, currents, and seasons affect ocean energy availability. Coastlines, underwater features, and weather patterns all play a role. Knowing these influences helps us pick the best spots and tech for ocean energy projects.

Global Ocean Energy Distribution

Tidal Range Variations

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• Tidal ranges vary significantly across the globe due to differences in coastal geography and ocean basin characteristics
• Locations with high tidal ranges (Bay of Fundy, Canada) experience tides up to 16 meters, while other areas have minimal tidal fluctuations
• Tidal range is influenced by factors such as the shape of the coastline, the width of the continental shelf, and the presence of resonant effects in semi-enclosed basins
• Regions with high tidal ranges are prime candidates for tidal energy extraction using technologies like tidal barrages or tidal stream turbines

Wave Energy Hotspots and Distribution

• Wave energy is unevenly distributed across the world's oceans, with certain regions exhibiting higher wave power densities
• Hotspots for wave energy include the western coasts of continents, such as the west coast of Europe, North America, and Australia, where strong westerly winds generate powerful waves
• These regions benefit from long fetch distances, allowing waves to build up energy over vast expanses of open ocean
• Other notable wave energy hotspots include the southern tip of South America, the southern coast of Africa, and the northeastern coast of Asia
• Wave energy potential is typically expressed in kilowatts per meter (kW/m) of wave crest length, with values ranging from a few kW/m in sheltered coastal areas to over 100 kW/m in the most energetic locations

Ocean Thermal Energy Gradient Distribution

• Ocean Thermal Energy Conversion (OTEC) relies on the temperature difference between warm surface waters and cold deep waters to generate electricity
• The ocean thermal gradient is most pronounced in tropical and subtropical regions, where surface temperatures can exceed 25°C and deep water temperatures remain around 4°C
• Regions with high ocean thermal gradients include the equatorial Pacific, the Caribbean Sea, and the waters around Hawaii and other Pacific islands
• OTEC systems require a temperature difference of at least 20°C between the warm surface water and the cold deep water to operate efficiently
• The global distribution of ocean thermal gradients determines the feasibility and potential locations for OTEC power plants

Salinity Gradient Energy Locations

• Salinity gradient energy, also known as osmotic power, harnesses the energy released when two solutions of different salinities mix, such as freshwater from rivers meeting seawater at river mouths or estuaries
• Locations with significant salinity gradients are found where large rivers discharge into the ocean, creating a sharp contrast between the low-salinity river water and the high-salinity seawater
• Notable salinity gradient energy locations include the mouths of major rivers like the Amazon, Mississippi, Congo, and Yangtze, as well as fjords and coastal lagoons with restricted water exchange
• The potential for salinity gradient energy depends on factors such as the volume and flow rate of the freshwater source, the salinity difference between the two water bodies, and the availability of suitable sites for energy extraction facilities

Factors Affecting Ocean Energy Availability

Influence of Marine Current Patterns

• Ocean currents play a crucial role in the distribution and availability of ocean energy resources
• Large-scale ocean circulation patterns, such as the Gulf Stream, Kuroshio Current, and Antarctic Circumpolar Current, transport vast amounts of water and energy across ocean basins
• These currents are driven by wind stress, density differences, and the Earth's rotation (Coriolis effect), creating persistent flows that can be harnessed for energy production
• Tidal currents, generated by the gravitational pull of the moon and sun, are another important source of marine current energy, particularly in coastal areas with high tidal ranges and constricted channels
• The strength, direction, and variability of marine currents determine the suitability of a location for ocean current energy extraction using technologies like underwater turbines or tidal stream generators

Geographical Factors Affecting Ocean Energy

• The geographical characteristics of a region significantly influence its ocean energy potential
• Coastline morphology, including the presence of headlands, bays, and narrow channels, can enhance or diminish the local tidal range and current velocities
• Bathymetry, or the underwater topography, affects wave propagation and the formation of wave energy hotspots, with shallower continental shelves and underwater ridges focusing wave energy
• The proximity to land and the availability of suitable sites for energy infrastructure, such as grid connections and maintenance facilities, are important considerations for ocean energy development
• Local environmental factors, such as the presence of marine protected areas, shipping lanes, or fishing grounds, can constrain the deployment of ocean energy technologies in certain locations

Seasonal Variations in Ocean Energy

• Ocean energy resources exhibit seasonal variability due to changes in atmospheric and oceanographic conditions throughout the year
• Wave energy tends to be highest during the winter months in the northern and southern hemispheres, when storms are more frequent and intense, generating larger and more powerful waves
• Tidal energy is influenced by the lunar cycle, with spring tides (higher tidal range) occurring around the times of the new and full moon, and neap tides (lower tidal range) occurring during the first and third quarter moons
• Ocean thermal gradients can vary seasonally, with the strongest gradients typically observed during the summer months when surface waters are warmest
• Salinity gradients may fluctuate depending on the seasonal flow patterns of rivers, with higher freshwater input during rainy seasons or snowmelt periods
• Understanding and predicting seasonal variations in ocean energy resources is crucial for optimizing energy production and ensuring the reliability of ocean energy systems