Page 30 - European Energy Innovation - autumn 2019 publication

30 Autumn 2019 European Energy Innovation

COMMUNICATION

RAISELIFE project extends the lifetime of
functional materials for Concentrated
Power Technologies

Several functional materials, with a main focus on reflectors, absorbers and structural materials,
are being developed and tested within the RAISELIFE project. System simulation tools are
being used to carry out a techno-economic analysis over the lifetime of the plant for the most
promising material developments.

Concentrated Solar Power (CSP) were first implemented commercially systems has been developed based
technologies in combination with in 2008. on cost-efficient sol-gel technology.
Thermal Energy Storage (TES) provide The coating achieves excellent optical
flexibility to the electrical grid, which The large initial investment for performance and high durability
is especially important as the share CSP plant construction does not (α=95.4%, ε=7.8% at 250°C, stability
of fluctuating wind and photovoltaic come without risk: degradation of >15 months in furnace at 400°C
power generation continues to components and materials can without degradation). In addition, an
grow in the energy mix. CSP has hinder the plant’s profitability. CSP improved anti-reflective (AR) coating
experienced a high learning rate in plants are typically designed for a has been developed for evacuated
the past years, being able to provide life span of 30 years, requiring the line focusing systems, reaching 2.5
renewable electricity at prices as materials to withstand extreme higher abrasion resistance compared
low as 6 c€/kWh including storage thermal loads as well as harsh desert to the state of the art. The novel AR-
for 6-15 hours. For these reasons the environment with high radiation and coating has already been deposited in
worldwide installed CSP capacity has dust erosion levels. a commercial receiver tube factory.
increased by a factor of 10 in the past
decade, reaching 5.5 GWel today, and The RAISELIFE project aims at With regards to solar tower CSP
further growth being expected. developing novel materials with plants, four different types of novel
extended lifetime and performance absorber coatings for temperatures
The first generation of CSP for parabolic-trough and solar tower up to 750°C have been developed.
technology consisted of direct-steam CSP plants. In addition, improved Durability testing of those coatings is
receivers without storage. The second testing and qualification methods being carried out in two sets of tests
generation CSP plants integrate TES to simulate in-service conditions under high solar flux (reaching up to
in molten nitrate salts; either at in different climates are being 700 kW/m²) and in several climatic
400°C for parabolic-trough collector developed. chambers to mimic both, operation
or at 565°C for solar tower technology conditions at high temperature and
(see Fig.1). The commercial With regards to parabolic-trough environmental corrosion and erosion
deployment of 1st gen. CSP plants CSP plants, a novel absorber coating at ambient temperature during
started in 1984, while 2nd gen. plants for non-evacuated line focusing night time or plant shutdown. Fig.
2 shows one of the two employed
Fig. 1: Schematic of molten salt receiver panel in solar tower plants on-sun testing facilities. Two of the
(only for illustration purposes; the image on the right shows the Ivanpah tested coatings were identified as
solar tower plant in California, which operates with steam instead of very promising: they showed similar
molten salt.) optical performance as the state
of the art Pyromark 2500 absorber
coating but significantly higher
durability. In addition, protective
coatings to prevent corrosive attack
from the molten salt on the inner
side of the metallic tube substrates
have been developed. The coated
samples showed only negligible
mass losses during furnace testing in
solar salt at 580°C for 10,000 hours,
opening the pathway to use low-
alloyed steels in combination with

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