Page 31 - European Energy Innovation - autumn 2019 publication

Autumn 2019 European Energy Innovation 31

COMMUNICATION

coatings for the molten salt storage Fig. 2: Accelerated aging testing of different absorber coatings in the
and piping systems, which will allow dish concentrator test bench at Plataforma Solar de Almería.
for further cost reductions compared
to the use of expensive nickel base Fig. 3: Schematic of silvered-glass mirror mounted on heliostats to
alloys. The corrosion rate of different reflect solar radiation towards the receiver
uncoated substrate materials has
been evaluated as reference: for The research leading to these results has received
the ferritic steels, Vallourec’s VM12 funding from the European Union’s Horizon 2020
performed significantly better than research and innovation programme under grant
T91. Low corrosion rates were agreement No. 686008, project RAISELIFE.
measured on nickel base alloys
Inconel617 and Haynes230. Contact details:
Dr. Florian Sutter, German Aerospace Center (DLR)
CSP plants make use of silvered- E-mail: florian.sutter@dlr.de
glass mirrors to focus the solar
radiation towards the receiver (see
Fig.3). Traditional glass mirrors have
a thickness of 4 mm and the silver
layer is protected on the back by a
thin copper film and 3 protective
paint lacquers. Within RAISELIFE,
different options to replace the
3-coat protective lacquers by a more
cost efficient 2-coat system are being
explored. Six types of novel 2-coat
lacquer systems are being tested
in an extensive outdoor exposure
campaign at 11 sites, as well as in a
set of accelerated climate chamber
tests. Five of the tested mirror
types (one of them completely lead
free) seem suited for dry desert
sites of low corrosivity, allowing to
reduce mirror cost below 12 €/m².
In addition, 8 types of anti-soiling
coatings to reduce mirror soiling
and therefore the cleaning cycle are
being tested. Furthermore, a thin-
glass heliostat prototype was built
and tested in Israel. The composite
backing structure proved to provide
stability against high wind loads
and sufficient resistance against
shape deformation caused by
gravity or temperature differences.
The reduction of glass thickness
from 4 mm down to 200 µm has
the potential to increase mirror
reflectance from 94.5% (state of
the art) up to 96.0% due to reduced
absorptance losses in the glass.

A public workshop to disseminate the
RAISELIFE results will be held on 21st
of November 2019 at the Vallourec
Research Center Germany. Interested
guests may register free of charge
under https://www.raiselife.eu l

www.europeanenergyinnovation.eu