Tests measure solar mirror efficiency

Highly reflective aluminium mirrors built by Alcoa are being tested at the US Department of Energy’s National Renewable Energy Lab (NREL) test facility in Golden, Colorado.

Currently, commercial concentrating solar power (CSP) systems use glass mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce utility scale electricity via a steam turbine.

Now, engineers at Alcoa have developed an alternative — highly reflective aluminium mirrors — which they claim are not only more durable than fragile glass-based mirrors, but will lower the installation cost of CSP systems.

NREL and Alcoa recently installed a new CSP parabolic collector made from the aluminium mirrors at the US Department of Energy’s NREL facility in Golden, Colorado.

A series of tests will now measure the 20 x 46ft collector’s efficiency as well as evaluating its structural performance. Results are expected by the second quarter of 2010, after which the system will enter its next level of large-scale testing.

One of the benefits of CSP technology is that thermal energy can be stored and drawn upon during short periods of clouds and at night. Therefore, the technology provides better grid stability and increased capacity factors compared with photovoltaic applications.

The project is being partially funded by a $2.1m (£1.4m) grant from the US Department of Energy.