13-05-2014, 02:34 PM
Parabolic Solar Water Heating System
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Introduction
Parabolic-trough solar water heating is a well-proven technology that directly substitutes renewable energy for conventional energy in water heating. Parabolic-trough collectors can also drive absorption cooling
Systems or other equipment that runs off a thermal load. There is considerable potential for using these technologies at Federal facilities in the Southwestern United States or other areas with high direct-beam solar radiation.
Facilities such as jails, hospitals, and barracks that consistently use large volumes of hot water are particularly good candidates
This Federal Technology Alert (FTA) from the Federal Energy Management
Program (FEMP) is one of a series on new energy-efficiency and renewable energy
Technologies. It describes the technology of parabolic-trough solar water-heating and absorption-cooling systems, the situations in which parabolic-trough systems are likely to be cost effective, and considerations in selecting and designing a system
Implementation Barriers
There are no technological barriers to using parabolic-trough solar water heating.
However, trough collectors are by nature limited geographically to areas with high
Direct-beam solar resources. They are also by nature more cost effective for facilities that use large amounts of hot water 7 days a week. But, because they directly replace conventional energy use, parabolic-trough collectors will provide energy savings and environmental benefits proportional to their use. From a financial perspective, however,
relatively high conventional water-heating costs will be the biggest enabling factor.
ESPC financing also provides advantages such as tax breaks for private investors that are important to project economics. Improvements in reflective and absorbent
Coatings and development of triple-effect absorption cooling will incrementally
Improve economics, but there are no known technological developments that could dramatically lower the cost of parabolic-trough solar water-heating or absorption-cooling systems. Much higher sales volume would likely lower costs, but that would depend on the new technology being able to consistently compete with low-cost conventional energy. Parabolic-trough solar water heating is likely to remain most cost effective where natural gas is not available or is relatively expensive, and where consistent high volume use provides economies of scale.
Application
More likely to be effective in areas such as the Southwestern United States that have good
Solar resources dominated by direct-beam sunlight. It is also more cost effective
Domestic water heater, water heating systems serving multiple buildings from a central steam or hot-water plant.