By: Susan Kraemer
Alcoa is working with the NREL, funded by a $2.1 million DOE grant under the Recovery Act funding for renewable energy – to develop cheaper, more durable aluminium mirrors to replace relatively fragile glass mirrors for use in solar CSP technology.
This summer’s tests of the 20-foot by 46-foot solar collector will evaluate its efficiency and structural performance outdoors at NREL's test facility in Golden, Colorado.
How CSP works:
The way the technology works is simple. Concentrated Solar Power (CSP) uses curved reflective surfaces to focus collected sunlight on a single point in order to heat a fluid; creating steam to drive a turbine to generate power.
Cheaper materials; mass production
By replacing the glass in parabolic troughs with reflective aluminum and integrating the mirror into a single structure that could be built using the high-volume manufacturing and assembly techniques used in the aerospace and automotive industries to lower installation costs; allowing easy "drop in place" installation, Alcoa thinks they can reduce costs by 20%.
They also aim to reduce both the weight (and thus the cost) of the support structure behind the mirrors.
"If you go out and look behind large parabolic troughs, you'll find an elaborate truss structure," said Rick Winter, a technology executive with Alcoa. "From our understanding of aerospace structures, we said if we can modify the wing box design used in aircraft and integrate a parabolic reflector, it would give us a light and stiff structure that would fundamentally affect the cost equation."
An airplane's wing box is a unit that integrates support structures and anchors a wing.
Low tech improvements can reduce costs
These kinds of simple mechanical improvements are actually more effective in reducing the cost of solar power in the very short term than breakthroughs in lab experiments that can take years to be developed at scale.
They should see test results by the second quarter of 2010 and be able to begin large-scale testing this Fall. Google is also working on reducing the cost of CSP.
Easiest “technology switch” to replace coal-fired electricity jobs
This form of solar technology is the closest to traditional coal-fired power since, at the end, it uses steam to drive turbines, just like coal power does. It is possible that in some regions coal power stations could be retrofitted to add CSP troughs to collect sunlight to make the steam to drive previously coal-fired steam-driven turbines.
Alcoa's Technical Center is located outside Pittsburgh, Pennsylvania, where rust belt jobs languish, and where coal jobs are in need of a replacement.
A major U.S.-based manufacturer entering the Concentrating Solar Power market can only be good for the hard-hit rust belt economy, while also helping the US transition to all the clean, safe, and fuel-free sources of renewable energy we all need for a prosperous energy-secure future.