Harvesting Ocean Energy

Energy can be harvested from the oceans in five basic ways, with a multitude of variations.

1. Tides - Potential energy contained in tides can be harnessed by building barrage or other forms of construction across an estuary.
2. Waves - Kinetic and potential energy in ocean waves can be harnessed using modular technologies.
3. Tidal or marine currents - Kinetic energy in tidal (marine) currents can be harnessed using modular systems.
4. Temperature gradients - Thermal energy due to the temperature gradient between the sea surface and deepwater can be harnessed using different Ocean Thermal Energy Conversion (OTEC) processes.
5. Salinity gradients - At the mouth of rivers where fresh water mixes with salt water, energy associated with the salinity gradient can be harnessed using pressure-retarded reverse osmosis process and associated conversion technologies.

High-tech Technology in the Solar Thermal Industry

The solar thermal industry has used low-tech technology until relatively recently and been largely concerned with small domestic and building applications for heating space or water, or cooking by solar power. However, the solar thermal industry is now taking a more sophisticated direction and progressing to higher-tech solar power applications involving relatively large electricity generation projects in a number of countries. Some of these solar power electricity generation schemes have been in existence for a number of years on a trial basis.

Solar cooling, although still a very small application with around 80 solar cooling systems in the world, is making rapid strides.

Solar thermal collectors are divided into three categories, according to temperature, with low, medium, or high temperature collectors. Low temperature collectors are flat plates generally used to heat swimming pools directly. Medium-temperature collectors are also usually flat plates and are used directly for creating hot water for residential and commercial use. High temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production. These are known as CSP (concentrating solar power) units. In use described as ‘direct’ the solar energy or heat is used to heat water or buildings, or for factory process, and not transformed into electricity.