APRIL 30, 2025
Issue 1
NEWSLETTER
COMPASsCO2
Con en s
Main Accomplishmen s
P ojec Managemen & Coo dina ion
Communica ion, Dissemina ion & Exploi a ion Ac i i ies
How o Access COMPASsCO2 Ou comes
This p ojec has ecei ed unding om he Eu opean Union’s Ho izon 2020
Resea ch and Inno a ion Ac ion (RIA) unde g an ag eemen No. 958418.
Issue : IX
Main Accomplishmen s
COMPASsCO2 Scien i ic Ou comes & Achie emen s
WP 1 (Ma e ials ope a ion condi ions and
hei easibili y s udies): This WP ocused on
de ining sys em pa ame e s and e alua ing he
easibili y o ma e ials and echnologies o a
supe c i ical CO₂ (sCO₂) sola powe sys em.
Ten di e en sCO₂ B ay on cycle con igu a ions
we e assessed, leading o he selec ion o
op imal p ocess condi ions—including a 700°C
u bine inle empe a u e a 260 Ba s and
pa icle/sCO₂ hea exchange pa ame e s—
owa ds a maximized e iciency o app ox. 49%.
Based on hese condi ions, candida e ma e ials
o bo h hea exchange componen s and hea -
ans e pa icles we e p e-selec ed o hei
abili y o pe o m unde ex eme he mal and
mechanical s ess. WP1 also in es iga ed bo h
low- and high-p essu e hea exchange
designs, pe o ming he mo-mechanical s ess
analyses o alida e ma e ial choices, and
ul ima ely inalized a modula indus ial-scale
hea exchange design capable o ans e ing
o e 200 MW h wi h 15 MW h pe module. A
comp ehensi e echno-economic analysis was
ca ied ou , e alua ing he p oduc ion cos s o
no el pa icles and es ima ing hea exchange
cos s using expe imen al and comme cial
benchma ks. Fi e concen a ed sola powe
(CSP) plan con igu a ions we e analyzed in
e ms o cos , e iciency, and le elized cos o
elec ici y (LCOE). Addi ionally, no el C -based
alloys and coa ings om WP3 we e assessed,
con i ming he economic easibili y o coa ings
such as C /Si slu y (~750 €/m²), while bulk C
alloys ace duc ili y limi a ions. The wo k also
included ma ke s udies a ge ing he
Medi e anean and MENA egions, iden i ying
b oade applica ions o he de eloped
ma e ials, such as C -Si coa ing o gas u bine
blades and indus ial p ocess hea a high
empe a u e and ha sh en i onmen .
WP2 (De elopmen and Tes ing o Pa icles):
I ocused on he de elopmen , es ing, and
op imiza ion o no el hea - ans e pa icles o
use in high- empe a u e sola applica ions.
S a e-o - he-a pa icles do no main ain a
cons an sola abso p ance a e he mal
es ing, making hem subop imal o use in
Concen a ed Sola Powe (CSP) applica ions.
No el pa icles de eloped by Sain -Gobain o e
signi ican pe o mance imp o emen s,
including s able sola abso p ance, be e
mechanical s ess dis ibu ion, and can be
p oduced a a simila cos . Among hese, Fe Ox
pa icles we e selec ed as he bes op ion due
o hei inc eased ha dness compa ed o o he
g anula ed pa icle gene a ions, despi e ha ing
ela i ely lowe sola abso p ance. To enhance
sola abso p ance, h ee coa ings wi h di e en
composi ions and applica ion echniques we e
Resea ch ocus: New
pa icles, me al alloys
and hea exchange
Du a ion: 1
No embe 2020 –
30 Ap il 2025
Team: 12 pa ne s
om 7 coun ies
de eloped by CIEMAT, DLR, and DFI.
En i onmen al and he mal es ing ha e shown
ha he coa ings main ain s able op ical
p ope ies. A e he mal es s, DFI coa ings
exhibi ed he highes sola abso p ance, while
CIEMAT coa ings expe ienced he lowes
decay. No ably, DLR coa ings sligh ly imp o ed
sola abso p ance a e es ing, indica ing ha
he hea ea men applied a e deposi ion was
insu icien o ully comple e he cu ing p ocess.
In e ms o ab asion esis ance, all h ee
coa ings pe o med simila ly a ambien
empe a u es. Howe e , du ing ab asion es ing
a ope a ional empe a u es, he DFI coa ing
expe ienced he g ea es loss in sola
abso p ance, while he DLR coa ing showed he
lowes abso p ance loss. The highes sola
abso p ance a he end o he es was achie ed
by he CIEMAT coa ing.
WP3 (De elopmen o Me als): This WP
ocused on he de elopmen o ad anced
ch omium-based ma e ials o high-
empe a u e, co osi e en i onmen s ypical o
pa icle- o-sCO₂ hea exchange s. The eam
designed and syn hesized C -NiAl bcc-
supe alloys
1
and C -Si alloys
2
ha
demons a ed excellen he mal s abili y up o
1000°C, high s eng h, and supe io oxida ion
and co osion esis ance, all a a lowe ma e ial
cos han con en ional nickel-based
supe alloys. Howe e , hei applica ion as
s uc u al ma e ials was limi ed by hei
b i leness, due o high duc ile- o-b i le
ansi ion empe a u es (abo e 600–700°C). To
add ess his, WP3 also de eloped and pa en ed
an inno a i e C /Si slu y di usion coa ing
p ocess, which was success ully applied o
comme cial s eel and nickel alloys such as
Inconel 740 and Rene 80. These coa ings
exhibi ed ou s anding oxida ion esis ance,
showed no ca as ophic co osion e en unde
long- e m and cyclic condi ions, and p o ed
highly e ec i e agains ho co osion in sodium
sul a e en i onmen s. Mechanical and
en i onmen al es s, including small punch and
c eep expe imen s, con i med high s eng h bu
also b i leness in he bulk alloys. In con as ,
coa ed ma e ials pe o med well unde e osion
and oxida ion, wi h TEM and EPMA analysis
1
h ps://doi.o g/10.1016/j.ac ama .2023.119183
e ealing he o ma ion o s able SiO₂ and Al₂O₃
subscales. To suppo ma e ial design, machine
lea ning and he modynamic modeling we e
used o sc een alloy composi ions, iden i ying
eigh p omising candida es— i e o which
ma ched he desi ed BCC-B2 mic os uc u e
upon expe imen al alida ion. A omis ic
simula ions u he e ined p edic ions ela ed o
duc ili y and phase s abili y.
WP4 (E alua ion and Modelling o
Me al/Medium In e ac ion): I e alua ed he
pe o mance and deg ada ion beha io o hea
exchange ma e ials unde ealis ic high-
empe a u e and high-p essu e en i onmen s.
The e osion beha io o ma e ials is in luenced
by pa icle ype, pa icula ly ha dness, and
eloci y, wi h C -Si coa ings showing a
bene icial e ec in mi iga ing e osion. In e ms
o c eep beha io , he obse ed da a aligns wi h
li e a u e alues, wi h minimum c eep a es
unde all selec ed loads being less han 10^-6
s^-1. Sanic o 25 showed highe c eep a es in
CO2, while IN-617B displayed simila beha io ,
and he e we e some de ia ions obse ed
among he supe alloys. O e all, he a mosphe e
had e y li le impac on he c eep beha io , and
he load had a minimal e ec on su ace
deg ada ion. Demons a o es s conduc ed a
700°C and 120 ba equi ed de elopmen s in
sealing, pumps, and senso s. Fo s a e-o - he-
a (SOTA) alloys, o med laye ed oxide scales
we e obse ed, wi h IN740 showing he lowes
oxida ion. No el alloys exhibi ed simila
beha io o SOTA alloys, al hough some g ain
bounda y oxida ion was no ed. In he ield o
modeling, expe imen al da a was success ully
implemen ed, e ealing ha ac u es a e likely
o ini ia e due o impac s a su ace oxide
aspe i ies. Li e ime modeling was comple ed by
es ima ing he wea a e and dep h o HEX
ma e ials.
WP5 (Technology Valida ion): This WP
ocused on he design, es ing, and alida ion o
a high-pe o mance pa icle/sCO₂ hea
exchange (HEX) o concen a ed sola powe
applica ions. A HEX mock-up was designed,
manu ac u ed and es ed, inco po a ing insigh s
om WP1 h ough WP4 o selec op imal
2
h ps://doi.o g/10.1007/s11085-024-10257-8
ma e ials—such as coa ed s eels and C -based
alloys—and con igu e he hea exchange
geome y. Key design challenges, including
p essu e d op, mechanical s ess, pa icle low,
and manu ac u abili y, we e sys ema ically
add essed. Ini ial cold loop es ing e alua ed
pa icle low beha io , helping o de e mine he
ideal ube pi ch and a angemen o balancing
he mal e iciency and pa icle low pa e n.
Subsequen ho -loop es ing was conduc ed
using a lab-scale ig ope a ing a ~750°C, whe e
he ab asion esis ance o s a e-o - he-a
ma e ials, as well as he WP3 C -based
ma e ials and coa ings, was e alua ed. In
addi ion, he impac esis ance o a ious
ce amic ma e ials was assessed. These es s
p o ided insigh in o wea du abili y and coa ing
s abili y unde cyclic ope a ion. In he inal
phase, a mock-up pa icle/sCO2 hea
exchange was manu ac u ed and es ed,
in eg a ing ac ual pa icle low and a unc ioning
sCO₂ loop. The es ing con i med he mal
pe o mance unde ep esen a i e condi ions,
achie ing Technology Readiness Le el 5 (TRL
5). Finally, expe imen al da a om WP5 ed
back in o echno-economic assessmen s om
WP1, e ining indus ial HEX design, imp o ing
pe o mance o ecas s, and enhancing cos
models o comme cial-scale CSP deploymen .
WP5 Final es ig – in eg a ed pa icle/sCO2 hea
exchange mock-up
P ojec Managemen & Coo dina ion
Regula p ojec mee ings, qua e ly phone calls,
and mon hly WP mee ings ensu ed smoo h
coo dina ion ac oss he COMPASsCO2
conso ium, allowing pa ne s o align on
echnical p og ess, challenges, and nex s eps.
These in e ac ions os e ed e ec i e
collabo a ion, kep he p ojec on ack, and
helped main ain a high s anda d o scien i ic and
echnical excellence. In addi ion, h ee e iew
mee ings wi h an ex e nal expe we e held o
p esen p ojec indings, and ge an e alua ion
o he wo k conduc ed (see below).
P ojec Mee ings
Eigh P ojec Mee ings (Gene al Assembly –
GA) we e o ganized o discuss he o e all
p og ess, in e ms o miles ones, deli e ables,
echnical p og ess achie ed, isk/de ia ions
and co ec i e ac ions, e c. While he Kick-o
mee ing had o be o ganized online because o
he Co id19 pandemic, h ee physical mee ings
we e held in 2022, 2023 and 2024.
Fou h GA Mee ing a Pla a o ma Sola
de Alme ia (PSA), Tabe nas, Spain, 30
No embe - 1 Decembe 2022
Fi h GA Mee ing a FZJ, Jülich,
Ge many, 6-7 June 2023
Six h GA Mee ing a SGCREE,
Ca aillon, F ance
31 Janua y – 1 Feb ua y 2024
Re iew Mee ings
Th oughou he COMPASsCO2 p ojec , 3
Re iew Mee ings wi h he Eu opean
Commission and an independen expe we e
held o assess p og ess, sha e key esul s, and
align on u u e ac i i ies. These mee ings
p o ided aluable eedback, ensu ing ha
echnical achie emen s, dissemina ion e o s,
and p ojec managemen emained on ack.
Each e iew con i med he quali y o he wo k
pe o med and highligh ed COMPASsCO2’s
s ong con ibu ion o ma e ial esea ch, sCO₂
p ocesses and CSP echnologies.
Fi s Re iew Mee ing a JCR,
Se aing, Belgium, 7 Ap il 2022
Second Re iew Mee ing, Online, 21 Ma ch
2024
Thi d Re iew Mee ing a CVR, Husinec u
Řeže, Czech Republic, 25 Ap il 2025
Communica ion, Dissemina ion & Exploi a ion Ac i i ies
The COMPASsCO2 p ojec has e ec i ely
sha ed i s indings h ough a a ie y o
p es igious in e na ional and in e disciplina y
pla o ms. These include published pape s in
enowned scien i ic jou nals, engaging
p esen a ions a con e ences and wo kshops,
in o ma i e pape s, wo kshops and webina s.
The p ojec 's impac was also ex ended h ough
digi al pla o ms (e.g. websi e, Zenodo, social
media) and o he ou each e o s, ensu ing
widesp ead dissemina ion o esea ch
ou comes.
Pape s P oduced by COMPASsCO2 Team
The COMPASsCO₂ p ojec has gene a ed a
wide ange o impac ul scien i ic publica ions
in pee - e iewed jou nals (13 in o al)
add essing majo challenges in concen a ing
sola powe (CSP) echnologies and high-
empe a u e ma e ials. In he ield o pa icle
de elopmen and coa ings, a echnical guideline
was published on he Sola PACES websi e in
May 2022, s anda dizing me hods o e alua ing
he op ical p ope ies o sola abso be pa icles.
Fu he esea ch published in May and
No embe 2022 demons a ed signi ican
pe o mance imp o emen s h ough he use o
black oxide and aluminum-inco po a ed deep
black pigmen coa ings. Addi ional wo k on
soiling cha ac e iza ion a iabili y appea ed in
Sola Ene gy Ma e ials and Sola Cells in July
2023, alongside esea ch published in Janua y
2024 on spinel abso be coa ings enhancing
CSP ecei e e iciency. Du abili y es ing o
no el pa icles was also epo ed in Sola
Ene gy Ma e ials & Sola Cells in No embe
2024. In he a ea o alloy de elopmen ,
publica ions in Physical Chemis y Chemical
Physics (May 2023) and Ac a Ma e ialia (July
2023) explo ed ad anced echniques o
p ecipi a e measu emen using deep lea ning
and he s eng hening o ch omium-based bcc-
supe alloys h ough i on supplemen s.
P o ec i e coa ing echnologies we e u he
ad anced h ough esea ch on C /Si-slu y
di usion coa ings published in Ma e ials
(Decembe 2023), as well as s udies on
nanoc ys alline Y₂O₃-modi ied coa ings and
ch omium-silicon slu y coa ings, which
appea ed in Su ace and Coa ings Technology
(June 2024) and High Tempe a u e Co osion o
Ma e ials (July 2024), espec i ely. A
collabo a i e Round Robin Tes on abso p ance
and emi ance measu emen s was also
p esen ed a he Sola PACES 2022 Con e ence
in Ma ch 2024. Finally, a s udy ocusing on
ma e ial challenges and alloy selec ion o
pa icle/supe c i ical CO₂ hea exchange s was
accep ed o publica ion in Sola Ene gy in
2024. Al oge he , hese publica ions ac oss
high-impac jou nals such as Sola Ene gy
Ma e ials and Sola Cells, Coa ings Jou nal,
Ma e ials, and Ac a Ma e ialia e lec he
p ojec 's s ong scien i ic ou pu and i s
signi ican con ibu ion o ad ancing CSP
echnology and high- empe a u e ma e ial
pe o mance.
Beyond he p ojec ’s du a ion, he
COMPASsCO2 p ojec will p oduce mo e han
15 pape s ocused on ma e ials o high-
empe a u e applica ions, especially in
concen a ed sola powe (CSP) sys ems.
Topics include he oxide scale o ma ion and ho
co osion esis ance o ch omized Ni-based
alloys, no el C -Si alloys o high empe a u es,
and he s abili y o coa ings in pa icle hea
exchange s unde he mal cycling. Addi ional
s udies will add ess high- empe a u e e osion,
ab asion es ing o coa ed pa icles, and
sc eening o ch omium-based high en opy
supe alloys. Resea ch will also explo e
oxida ion beha io o ma e ials o CSP plan s
wi h CO2 hea - ans e sys ems and he design
o BCC supe alloys. Finally, pape s will co e
he de elopmen o ch omium-silicon slu y
coa ings and he c eep beha io o Fe- and Ni-
based alloys in CO2 en i onmen s. These
s udies will con inue o con ibu e o ma e ial
ad ancemen s beyond he p ojec 's comple ion.
In addi ion o scien i ic pape s, he
COMPASsCO2 eam p oduced in o ma i e
pape s o sha e key p ojec esul s wi h a
gene al audience o aise awa eness o
esea ch de elopmen s and hei indus ial
applica ions o a Ne Ze o Ca bon u u e. Th ee
pape s we e eleased:
1. Fi s Pape (Ma ch 2022) – Focused on
he de elopmen and es ing o new
pa icles o high- empe a u e
concen a ing sola ecei e s,
highligh ing inno a ions om
COMPASsCO2.
10.5281/zenodo.11386468
2. Second Pape (No embe 2023) –
Co e ed new me al alloys o sCO2 hea
exchange s in nex -gen sola plan s,
including p ope ies o bulk ma e ials,
coa ings, and in e ac ions wi h hea
exchange s eel.
10.5281/zenodo.11385843
3. Thi d Pape (Ap il 2025) – Discussed
he de elopmen o ch omium-based
alloys o u u e concen a ing sola
echnologies.
10.5281/zenodo.15310616
COMPASsCO2 Pa icipa ion a Con e ences
The COMPASsCO2 p ojec has been widely
p esen ed a a ious in e na ional con e ences,
wo kshops, and e en s. P esen a ions (69 in
o al) include de ailed discussions on new
ma e ial solu ions o he mal ene gy s o age a
Sola PACES2021, and con ibu ions on BCC-
supe alloys and C -Si alloys a TMS 2022. The
p ojec also ea u ed se e al o al p esen a ions
and pos e s a con e ences such as ICMCTF,
Plansee Semina , and Sola PACES,
highligh ing opics like he de elopmen o
ad anced coa ings o CSP sys ems, oxida ion
beha io s o supe alloys, and he mal and
en i onmen al du abili y o no el pa icles.
O he no able sessions included co osion
beha io in mol en sal s, mechanical es ing o
ma e ials o sola hea exchange s, and
inno a ions in high empe a u e co osion and
e osion esis ance. O he p esen a ions
co e ed opics like alloy de elopmen , ma e ial
es ing, and pe o mance e alua ion a majo
con e ences such as TMS 2025 and
Sola PACES 2024.
Ma a Na as (CIEMAT) a EUROCORR
2024 con e ence, Pa is, F ance, 2-5
Sep embe 2024
Flo ian Lebendig (FZJ) Wins Bes
Pos e Awa d a HTCPM 2024
Symposium, Île des Embiez,
F ance, 9 -14 June 2024
Tom Blackbu n (UoB) a he High
Co osion and Oxida ion Wo kshop
2023, Ma k heiden eld, Ge many, 25-
29 Sep embe 2023
COMPASsCO2 pa ne s a he
EUROMAT2023, 03-07 Sep embe 2023,
F ank u , Ge many
CIEMAT colleagues a he 2023
MRS Con e ence, San F ancisco,
USA, 14 Ap il 2023
Flo ian Lebendig (FZJ) a he ade ai
o indus y ha was o ganized om
22 o 26 Ap il 2024 a Hanno e ,
Ge many. wi h Ms. Vic o ia Pe o a,
Head o Uni (HaDEA, Indus y Uni ).
COMPASsCO2 Wo kshops
COMPASsCO2 S akeholde s Wo kshops
In o de o in e ac wi h s akeholde s o
exchange knowledge, alida e esul s and
iden i y a eas o collabo a ion, he i s
COMPASsCO2 s akeholde s wo kshop was
o ganized on 10 June 2021 ia ideo-
con e encing. The wo kshop had he pu pose o
in oduce he p ojec , discuss he main esea ch
ac i i ies conduc ed, and iden i y a eas in which
o coope a e wi h o he p ojec s, ins i u ions o
companies. The main ocus a eas o his
wo kshop we e: he use o concen a ing sola
echnology and i s in eg a ion in he B ay on
cycle; e alua ion o s a e-o - he-a ma e ials
ha could wi hs and he ex eme ope a ing
condi ions; and esea ch, de elopmen and
es ing o inno a i e ma e ials ha gua an ee
eliabili y and sus ainabili y unde ha sh
condi ions.
The Second S akeholde s Wo kshop o he
COMPASsCO2 P ojec was held on 25
Sep embe 2023 in a hyb id o ma
(Ma k heiden eld, Ge many and online), a he
occasion o he in e na ional con e ence on high
empe a u e co osion and oxida ion. The
wo kshop was o ganized a ound wo main
sessions, he i s dealing wi h ad anced
ma e ials o ab asi e en i onmen s and he
second one ocusing on ma e ial beha iou in
sCO2 en i onmen s. Rep esen a i es om he
COMPASsCO2 conso ium p esen ed he
p elimina y esul s o hei analysis and had he
oppo uni y o in e ac wi h expe s indus y and
academia o u he ad ance on he wo k and
alida e he indings. The mee ing saw he
pa icipa ion o abou 60 pa icipan s.
Fi s S akeholde s Wo kshop
Second S akeholde s Wo kshop
COMPASsCO2 Final Wo kshop
The COMPASsCO₂ Final Wo kshop ook place
in a hyb id o ma on 24 Ap il 2025 – a CVR
p emises, in Husinec u Řeže, Czech Republic
and online—b inging oge he leading expe s o
e lec on ou yea s and a hal o inno a ion in
supe c i ical CO₂ (sCO₂) powe sys ems. Unde
he heme "Back o he Fu u e: A Fo wa d-
Thinking App oach o Concen a ing Sola
Technologies", he wo kshop agenda (shown
below) was s uc u ed in such a way o highligh
he main inno a ions b ough by he p ojec :
ad ancemen s in CST ecei e echnologies
using new pa icle ma e ials; design and es ing
o high- empe a u e alloys and coa ings; eal-
wo ld alida ion o ma e ials and sys ems unde
ex eme condi ions; and inal indus ial design
and business case o sCO₂ implemen a ion.
The a e noon echnical ou o e ed pa icipan s
a hands-on look a : sCO₂ au ocla e & e osion
es lab, sCO₂ loop & hea exchange es se up,
and ma e ial es ing & ho cell labs.
C SsC 2
anie Beni e
cie i he i u e
l Re e ch, e
u li ic i up,
R
a ue a in
R i ec he peci l
i e i i i i
he Ce ic e i l ch
CR
a ie on e o
e i cie i he i h
e pe u e e i l up,
eche chu i i u ,
u as e e
cie i he i u e l
Re e ch, i h e pe u e
ech l ie ep e ,
R
ha y ensonne
e el p e e i ee
l he l
e ep e ,
C
elcome, ojec e iew
and bjec i es n es iga ed sys em esc ip ion o sola plan
combined wi h ay on cycle, bene i s and
limi a ions
a e ials o hea
e change s ubes selec ion,
de elopmen and e alua ion
a e ials o hea ca ie
pa icles selec ion,
de elopmen and e alua ion
i l W k h p u i ec u Řeže, Czech Republic, 24 Ap il 2025
