Ocean Thermal Energy Conversion

Ocean thermal energy conversion (OTEC or OTE[1]) is hydro energy conversion system which uses the temperature difference that exists between deep and shallow waters to run a heat engine. As with any heat engine, the greatest efficiency and power is produced with the largest temperature difference. This temperature difference generally increases with decreasing latitude, i.e. near the equator, in the tropics. Historically, the main technical challenge of OTEC was to generate significant amounts of power, efficiently, from this very small temperature ratio. Changes in efficiency of heat exchange in modern designs allow performance approaching the theoretical maximum efficiency.

The Earth’s oceans are continually heated by the sun and cover nearly 70% of the Earth’s surface; this temperature difference contains a vast amount of solar energy which can potentially be harnessed for human use. If this extraction could be made cost effective on a large scale, it could provide a source of renewable energy needed to deal with energy shortages, and other energy problems. The total energy available is one or two orders of magnitude higher than other ocean energy options such as wave power, but the small magnitude of the temperature difference makes energy extraction comparatively difficult and expensive, due to low thermal efficiency. Earlier OTEC systems had an overall efficiency of only 1 to 3% (the theoretical maximum efficiency lies between 6 and 7%[2]). Current designs under review will operate closer to the theoretical maximum efficiency. The energy carrier, seawater, is free, although it has an access cost associated with the pumping materials and pump energy costs. Although an OTEC plant operates at a low overall efficiency, it can be configured to operate continuously as a Base load power generation system. Any thorough Cost-benefit analysis should include these factors to provide an accurate assessment of performance, efficiency, operational and construction costs and returns on investment.

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1. Ocean Thermal Energy Conversion

NIGHT VISION TECHNOLOGY

A night vision device (NVD) is an optical instalment that allows images to be produced in levels  of light approaching total darkness. They are most often used by the military and law  enforcement agencies, but are available to civilian users. The term usually refers to a complete  unit, including an image intensifier tube, a protective and generally water-resistant housing, and  some type of mounting system.

Many NVDs also include sacrificial lenses, IR illuminators, and telescopic lenses. NVDs are mounted appropriately for their specific purpose, with more general- purpose devices having more mounting options. For instance, the AN/PVS-14 is a monocular  night vision device in use with the US military as well as by civilians.

It may be mounted on the  user’s head for hands free use with a harness or helmet attachment, either as a monocular device,  or in aligned pairs for binocular “night vision goggles” which provide a degree of depth  perception as do optical binoculars. The AN/PVS-14 may also be attached to a rifle using a Picatinny rail, in front of an existing telescopic or red dot sight, or attached to a single-lens reflex  camera.

Other systems, such as the AN/PVS-22 or Universal Night Sight, are designed for a  specific purpose, integrating an image intensifier into, for example, a telescopic sight, resulting  in a smaller and lighter but less versatile system.

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1. Night Vision Techonology
2. NIGHT VISION TECHNOLOGY