Federal Technology Alert Parabolic-Trough Solar Water Heating Renewable technology for reducing water-heating costs A publication series Warren Gretz, NREL/PIX01019 designed to speed the adoption of energy- efficient and renewable technologies in the Federal sector Prepared by the New Technology Demonstration Program The U.S. Department of Energy requests that no alterations be made without permission in any reproduction of this document.
Parabolic-trough solar water heating is also explains energy savings performance a well-proven technology that directly sub- contracting (ESPC), a method for financing stitutes renewable energy for conventional Federal facility energy conservation and energy in water heating. Parabolic-trough renewable energy projects. ESPC is avail- collectors can also drive absorption cooling able for parabolic-trough systems and offers systems or other equipment that runs off a many important advantages. thermal load.
There is considerable potential Parabolic-trough collectors use mirrored for using these technologies at Federal facil- surfaces curved in a linearly extended ities in the Southwestern United States or parabolic shape to focus sunlight on a dark- other areas with high direct-beam solar radi- surfaced absorber tube running the length ation. Facilities such as jails, hospitals, and of the trough. A mixture of water and barracks that consistently use large volumes antifreeze or other heat transfer fluid is of hot water are particularly good candi- pumped through the absorber tube to pick dates.
Use of parabolic-trough systems helps up the solar heat, and then through heat Federal facilities comply with Executive exchangers to heat potable water or a ther- Order 12902's directive to reduce energy use mal storage tank. Because the trough mir- by 30% by 2005 and advance other efforts rors will reflect only direct-beam sunlight, to get the Federal government to set a good parabolic-trough systems use single-axis example in energy use reduction, such as the tracking systems to keep them facing 1997 Million Solar Roofs Initiative. the sun.
This Federal Technology Alert (FTA) from the Federal Energy Management Application Program (FEMP) is one of a series on new Use of parabolic-trough systems is more energy-efficiency and renewable energy limited by geography and system size than technologies. It describes the technology of are other types of solar water heating, but parabolic-trough solar water-heating and where parabolic troughs are usable they absorption-cooling systems, the situations often have very attractive economics.
As in which parabolic-trough systems are likely concentrating systems, parabolic troughs use to be cost effective, and considerations in only direct radiation, so are less effective selecting and designing a system. This FTA