The Scarabeus project, funded by the European Commission, seeks to reduce carbon emissions in solar thermal plants by introducing novel supercritical CO2 cycles in solar thermal plants. Abengoa participates in the project along with eight other partners, including universities and companies, from six different countries.

1. Supercritical CARbon dioxide/Alternative fluids
Blends for Efficiency Upgrade of Solar power plants
This project has received funding from
the European Union’s Horizon 2020
research and innovation programme
under grant agreement No 814985
SCARABEUS Consortium Members
www.polimi.it www.tuwien.at
www.us.es www.city.ac.uk
www.brescia.edu www.kelvion.com
www.quantis-intl.com
www.abengoa.eswww.exergy-orc.com
www.scarabeusproject.eu
SCARABEUS Contact
For further information, please contact:
GGiamppaaoolo MMMaannzzolinni (PProoojeeectt CCoooordddiinaaaatoorrr)
Dipartimento di Energia
Politecnico di Milano, Italy
Phone: +39 (0)22 399 3810
e-mail: giampaolo.manzolini@polimi.it
DDavvid SSáánccheeezz (DDissssemmiinaaattiionnn MMMaanaaaggeerrr)
Department of Energy Engineering
University of Seville, Spain
Phone: +34 95 448 6488
e-mail: ds@us.es
toorr)
April 2019 March 2023
WP Year 1 Year 2 Year 3 Year 4
1 Project management
2 Development Testing
3 Design Cost assessment
4 Design Manufacturing Cost assessment
5
Thermodynamic
assessment
Techno-economic optimisation
Life Cycle Assessment and Natural Capital
Valuation
6 Adaption of test-loop Testing phase
7 Disemination, Communication and Exploitation
Timeline
Project Information
Under the EU’s Horizon 2020 R&I Programme
Acronym: SCARABEUS
Grant Agreement ID: 814985
Duration: 4 years (1 April 2019 - 31 March 2023)
Programme: H2020-EU.3.3.2.
(Low-cost, low-carbon energy supply)
Topic: LC-SC3-RES-11-2018
(Developing solutions to reduce the cost and increase
performance of renewable technologies)
Call for Proposal: H2020-LC-SC3-2018-RES-TwoStages
Funding Scheme: RIA - Research and Innovation action
Budget: 4 950 266,25 € (100% EU funding)

2. Objective
The aim of the SCARABEUS project is to demonstrate that the
application of supercritical CO2
blends to CSP plants has the
potential to reduce CAPEX by 30% and OPEX by 35% with res-
pect to state-of-the-art steam cycles, thus exceeding the reduc-
tion achievable with standard supercritical CO2
technology. This
translates into a LCoE lower than 96 €/MWh, which is 30% lower
than currently possible.
The project will also demonstrate the innovative fluid and newly
developed heat exchangers at a relevant scale (300 kWth) for 300
h in a CSP-like operating environment.
Mission & Vision
Concentrated Solar Power (CSP) plants are set to play an im-
portant role in the energy supply mix in the twenty first century.
Unfortunately, the Levelized Cost of Electricity (LCoE) of CSP
(currently about 150 €/MWh) has not attained the level targeted
(100 €/MWh) except for few installations in exceptionally good
locations.
As of today, many ongoing research projects aiming at enhan-
cing the efficiency of the power block and reducing the associa-
ted costs are based on supercritical CO2
technology. However,
relatively high ambient temperatures, typical in regions charac-
terized by high solar irradiation, remain the Achilles heel of su-
percritical CO2
cycles as the efficiency of these systems drops
dramatically in warm environments where ambient temperature
is close to or higher than the critical temperature of CO2
(31°C),
hence not allowing to adopt condensation (Rankine) cycles with
expectedly higher efficiencies. This issue stems as an intrinsic cri-
tical hurdle for the future commercialization of CSP plants, which
may be difficult to overcome by any means with the technology
currently in use or with standard supercritical CO2
technology.
To address this limitation, SCARABEUS proposes a modified
working fluid whereby carbon dioxide is blended with certain ad-
ditives to enable condensation at temperatures as high as 60°C
• WWPP55 [USSEE] is focused on overall plant optimisation from both
thermodynamic and economic standpoints. In WP5, the CO2
blend to be validated in SCARABEUS through efficiency and
LCoE calculations is selected. In addition, WP5 defines the
operating conditions of the power block that are necessary
in WP3 for the design of the turbomachinery and in WP4 for
the design and manufacturing of the heat exchangers. Also in
WP5, Life Cycle Assessment (LCA) and natural capital assess-
ments performed with the aim to understand and evaluate
the environmental and social impacts of the SCARABEUS
technology.
• In WWWPP6 [[TUUUWW], the prototype air-cooled condenser and recu-
perative heat exchanger designed and manufactured in WP4
is tested in a dedicated experimental loop. Both components
are characterised, and a detailed cost assessment is perfor-
med. The experimental campaign in the loop is designed to
accumulate 300 hours of testing to enable endurance valida-
tion of the working fluid.
whilst, at the same time, still withstanding the required peak cy-
cle temperatures.
This presents a major breakthrough in CSP technologies as it
increases the thermomechanical conversion efficiency from the
current 42% to above 50%, bringing about large reductions in
LCoE. The two main areas of research in SCCCCARRRAABBBEUUUUSS (optimal
additives heat exchanger development) will lead to a significant
reduction of CAPEX and OPEX with respect to conventional CSP
technologies.
Structure
SCCAARAAABBEUUSS comprises activities covering the whole value chain
needed to prove thermodynamic, economic and environmental
benefits of the proposed technology. The work plan is divided
into five R&D work packages (WP2-6), WP1 [POLIMI] on pro-
ject management and coordination and WP7 [ABE] on disse-
mination, communication and exploitation with a cross-cutting
approach:
• WWPP22 [UNNIBBSS] is devoted to identifying the most promising
CO2
blends. The thermodynamic properties of these fluids
are determined and passed to WP5 for the thermo-economic
simulation and optimisation of SCARABEUS.
• WWPP33 [CIITTYYY] is focused on assessing the impact of the new
working fluids on the design and performance of turbomachi-
nery used in the system. To this aim, a full-scale axial turbine
will be designed and a suitable pump (SCARABEUS is based
on a condensing cycle) which could be adopted in a commer-
cial plant will also be selected. This WP covers both aerother-
mal and economic aspects of turbomachinery.
• WWPP44 [KEELLL] is aimed at assessing the impact of the new wor-
king fluids on the design and performance of the heat ex-
changers used in the system. The focus is on the high and low
temperature recuperator and on the condenser, which are the
critical heat exchangers in the cycle. The scope of this WP
includes manufacturing these equipment.