Concentrating solar power aluminum mirrors

NREL and Alcoa recently installed a new Alcoa-designed Concentrating Solar Power parabolic trough at NREL’s test facility in Golden, Colo., USA. The series of tests will measure the 20-foot by 46-foot collector’s efficiency to generate energy and evaluate its structural performance. This round of validation at NREL follows successful tests at Alcoa Technical Center outside of Pittsburgh, Pa., USA.

Currently, commercial Concentrating Solar Power systems installed to date 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.

Instead of glass mirrors, the new Alcoa solution uses highly-reflective aluminum mirrors, which are more durable and environmentally-friendly than fragile glass-based mirrors. The Alcoa design solution enables high-volume manufacturing techniques to lower installation costs, plus its monolithic structure enables a simple “drop-in-place” collector for easy installation. The Alcoa design includes sheet, extrusions and fasteners.

Installed by multinational aluminum company Alcoa, they will be tested at the DOE’s National Renewable Energy Laboratory before their industrial experimentation.

The National Renewable Energy Laboratory (NREL) and the multinational aluminum company Alcoa announced a partnership to develop a concentrating solar collector with aluminium mirrors.

Compared to conventional glass mirror collectors, aluminum ones have several advantages: they last longer, are less subject to damages and less expensive to assemble and install. According to Alcoa – which installed the first aluminum prototypes at its Technical Center in Pittsburgh – their life cycle is also more sustainable, under an environmental point of view.

The short term objective of the tests that will now be conducted at the NREL laboratories in Golden (Colorado) is to measure the energy efficiency and the structural performance of these new mirrors. Tests are partially funded by the US Department of Energy (DOE) with $ 2.1 million.

The results of this phase are expected to be known by mid 2010, and subsequently a large-scale test phase will to take place, according to the schedule.

One of the benefits of Concentrating Solar Power 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 to photovoltaic applications.

The project is being partially funded by a US$2.1 million DOE grant. Test results are expected by the second quarter of 2010, after which the system will enter its next level of large-scale testing.