March 20, 2010
Alcoa Aluminum Mirrors To Cut Concentrating Solar Cost
Using a design inspired by aluminum wings Alcoa aims to cut the cost of concentrating solar power (CSP) mirrors.
Current solar troughs use glass mirrors that are formed in the shape of a parabola and then attached to a support structure made of aluminum or steel. The executives said they estimate that the all-aluminum Alcoa parabolic trough, which is being tested at the National Renewable Energy Laboratory in Colorado, will cut the price of a solar field by 20 percent due to lower installation costs.
This comes on the heels of an even more ambitious effort by Google to cut CSP costs. Bill Weihl of Google says Google has a concentrating mirror design that might cut solar thermal costs by a factor of 2 or more.
Weihl said Google is looking to cut the cost of making heliostats, the fields of mirrors that have to track the sun, by at least a factor of two, "ideally a factor of three or four."
The timelines for both these technologies range up to 3 years before they are ready. The cost of concentrating solar looks headed on a downward course.
I don't know, I think the solar tower concept,
has more potential in the long run. It doesn't rely so much on clouds being absent, and inherently provides storage into the night. It can also be coupled with photovoltaics, for higher efficiency during the day, and can tap temperature inversions in the atmosphere for power, too.
Yes, "inversion" is the wrong term. A tall chimney can tap into the same forces which drive thunderstorms, only more efficiently, since it can constrain sideways expansion.
SolarFuel manufactures a reflective film that they incorporate into a parabolic trough for CSP. They claim 30% lighter weight troughs resulting in a 35% cost reduction.
The SkyTrough™ is SkyFuel’s high-performance parabolic trough solar concentrator for use in utility-scale solar-thermal power plants or industrial process heat applications. The SkyTrough™ design emphasizes ease of assembly, low mass, inexpensive components and value engineering. The result is a parabolic trough solar collector assembly (SCA) that is 35% less expensive than alternative parabolic trough designs in commercial operation. The SkyTrough™ is based on proven parabolic trough geometry but incorporates several key features that set it apart from the competition:
1.Unbreakable, non-glass mirrors using ReflecTech® Mirror Film;
2.Reflector panels have lower material cost and are installed faster;
3.The space frame is 30% lighter-weight;
4.Field assembly is achieved in half the time as the design has 40% fewer parts;
5.Use of new, larger diameter receiver tube reduces cost and increases performance;
6.More robust, higher performance and lower cost drive and control units; and
7.Structures that ship compactly.
SolarFuel also has a linear Fresnel CSP that uses molten nitrate salts for the heat transfer fluid (HTF) which can double as heat storage without the need for heat exchangers (and their losses) between the HTF and storage.
"Thermal energy storage is simple, does not degrade in performance over time, is inexpensive and remarkably compact: A full day's supply of power for a member of an average American household stored as thermal energy in a hot medium, such as molten salt, can fit in a five gallon bucket. "
Question: What would the cost of the salts and storage vessel/5 gal. be?