SCARABEUS represented at the 7th International Seminar on Organic Rankine Cycle Power Systems

The SCARABEUS project was well represented by researchers from University of Seville at the 7th International Seminar on Organic Rankine Cycle (ORC) Power Systems, held in Seville between September 4th and 6th.

Two papers were presented at the conference, dealing with different aspects of supercritical cycles working on Carbon Dioxide mixtures in Concentrated Solar Power applications:

  • Rodríguez de Arriba et al, Mapping the techno-economic potential of next-generation CSP plants running on transcritical CO2-based power cycles


Although the thermodynamic potential of transcritical/supercritical CO2-based power cycles for next generation Concentrated Solar Power plants has been already confirmed in literature, further investigation to assess the actual feasibility of this technology from a techno-economic standpoint is needed. In fact, large uncertainty is found when it comes to the estimation of the CAPEX and OPEX of the power block, and the same can be said for the solar subsystem when high Turbine Inlet Temperatures are considered (>700 ºC).

Bearing this in mind, this paper presents a methodology to map the techno-economic potential of next-generation Concentrated Solar Power plants running on CO2-based mixtures, with the final aim to identify the threshold (breakeven) costs of the main subsystems enabling a clear gain in terms of Levelised Cost of Electricity with respect to state-of-the-art steam-based CSP.

Two different systems are studied which differ in the composition and peak temperature of the Heat Transfer Medium: a SoA molten salts system operating at a TIT of 550 ºC (Gen I) and a solid particle system with TIT=700 ºC (Gen II). An integrated platform able to simulate all CSP plant subsystems and perform hourly calculations is built in Matlab employing Artificial Neural Networks to simulate the solar field, ensuring extremely high computational speed.

To overcome the high uncertainty in terms of cost estimation, a two-step analysis is developed: firstly, the CAPEX of the entire plant is calculated assuming correlations from literature, except for the power block, whose estimate brings about the largest uncertainty. As a result, the minimum power block cost allowing a LCoE lower than a certain target is identified. Secondly, an inverse methodology is applied, setting the power block cost and assessing the minimum CAPEX of the solar subsystem. As a result, a map is obtained showing the target CAPEX to be accomplished by sCO2+CSP if a clear reduction of the LCoE of this technology is to be achieved

  • Crespi et al., Operational optimisation of the main heat rejection unit of CSP plants based on carbon dioxide mixtures


This research, developed in the framework of the SCARABEUS project, studies the off-design performance of transcritical power cycles running on CO2-SO2 mixtures in Concentrated Solar Power applications. The objective of this work is to identify optimum operational strategies that maximise net energy production when exposed to variable ambient temperature, with special focus on the operation of the Heat Rejection Unit (Air-Cooled Condenser). The power cycle is simulated in Thermoflex, modified with user-defined scripts to account for the specific off-design performance characteristics of key components. The Air-Cooled Condenser is modelled by means of an in-house Matlab tool, already validated in previous publications, able to accurately simulate the heat transfer process between working fluid and cooling medium (air) and to calculate auxiliary power consumption.

Four different strategies are identified, depending on ambient temperature: variable or constant condensation pressure for ambient temperatures lower than the design value, and constant turbine inlet temperature or constant return temperature of the heat transfer fluid for ambient temperature higher than design value. The results show that a combination of variable and constant minimum cycle pressure is the best alternative for low ambient temperatures, enabling net system efficiencies higher than 41%. On the other hand, constant turbine inlet temperature enables higher net performance than constant return temperature of the heat transfer fluid, even if at the expense of a reduction in energy storage capacity for the same inventory of molten salts


The papers will be published in the Conference Proceedings and they will be available for download free of charge. Congratulations SCARABEUS team at University of Seville on this excellent dissemination action!

Final dissemination event in Seville

Prof. David Sánchez, Dissemination Coordinator of SCARABEUS

As announced in recent months, a final dissemination event was organised by the SCARABEUS project team with the aim to disclose the most relevant results and outcomes of the project. The event was collocated with the 7th International Seminar on Organic Rankine Cycle (ORC) Power Systems, held in Seville between September 4th and 6th. This conference takes place every two years, organised by the Knowledge Centre on Organic Rankine Cycle Technology – KCORC (reference organisation for the dissemination of all information related to ORC technology research, development and education).

The SCARABEUS dissemination event was held on Wednesday, September 6th, parallel to and jointly with the sessions of ORC 2023 and with the following agenda:

Time Content Speaker
8.00 – 8.40 Registration
Session 1 – Introduction and component development. Chair: Noelia Martínez
8.40 – 8.50 Welcome and introduction to SCARABEUS David Sánchez
8.50 – 9.20 Utilisation of Carbon Dioxide mixtures Michele Doninelli
9.20 – 9.50 Turbomachinery for Carbon Dioxide mixtures Andrea Paggini
9.50 – 10.20 Heat exchanger for Carbon Dioxide mixtures Markus Haider
10.20 – 10.50 Coffee break
Session 2 – System development and integration. Chair: Markus Haider
10.50 – 11.20 Techno-economic and environmental features of CSP plants using Carbon Dioxide Mixtures Francesco Crespi
11.20 – 12.00 Experimental activities in SCARABEUS Viktoria Illyes
12.00 – 12.30 Exploitation and next steps (panel) All speakers
12.30 – 12.55 Q&A
13.00 – 14.20 Lunch
Session 3 – Keynote. Co-organised with ORC 2023
14.20 – 15.00 Market report on organic Rankine cycle power systems – 2023 insights Christoph Weiland

Marco Astolfi

Session 4 – Supercritical Carbon Dioxide technology moving forward. Chair: Noelia Martínez
15.00 – 15.20 Enabling cost-effective energy storage – HYBRIDplus Cristina Prieto
15.20 – 15.40 Enabling very high temperatures in CSP applications Salvatore Guccione
15.40 – 15.55 Q&A – Exploitation pathway for sCO2 technology
15.55 – 16.00 Closure David Sánchez

Salvatore Guccione (Royal Institute of Technology KTH, Stockholkm), invited speaker at the event

The event was well attended and the opportunity to cross sessions with ORC 2023 was very much appreciated by the attendees. The representatives of the SARABEUS partners disclosed the activities carried out in each work package during the morning sessions. In the afternoon, the invited speakers -Dr. Cristina Prieto and Salvatore Guccione- provided the attendees with very new information about recently awarded EU projects that will enable the further maturation and exploitation of the SCARABEUS technology.


If you should wish to receive the presentations delivered by the speakers, get in contact with the Dissemination Coordinator of SCARABEUS: Prof. David Sánchez (

The fifth episode of the webinar series on R& Activities on sCO2 in Europe organized by ETN will take place on September 28th

As already published on this website, the CO2OLHEAT Project coordinated by ETN Global aims to demonstrate (at TRL7) the operation of a 2 MW Waste-Heat-to-power (WH2P) skid based on a 2MW-sCO2 cycle, able to efficiently valorize local waste heat at a significant temperature of 400°C in the CEMEX cement manufacturing plant in Prachovice (CZ).


ETN Global initiated, in September 2022, a series of webinars aimed at providing a forum where the R&D activities in the area of supercritical Carbon Dioxide technologies can be disseminated and made known to a wider audience. This initiative has been joined by nine international and national projects, funded by the Horizon 2020 and Horizon Europe programmes of the European Commission (CO2OLHEAT, COMPASsCO2, SCARABEUS, DESOLINATION, SOLARSCO2OL, sCO2-4-NPP , ISOP) and by national R&D programmes in Germany (CARBOSOLA) and the Czech Republic (sCO2-Efekt).


The first webinar, held on September 22nd, aimed to introduce these projects in a single session, providing the main features of the project from technical and administrative standpoints. Opportunities for collaboration between projects and with stakeholders were also highlighted. Presentations can be downloaded from the SCARABEUS website: Link.


The second webinar took place on December 5th and presented a focus session discussing the fundamental and technical challenges posed for the design and operation of compressors in Supercritical Carbon Dioxide power systems. Three outstanding speakers covered these aspects; the session turned out very well and the feedback was very positive. Presentations can be downloaded from the SCARABEUS website: Link.


The fourth event was organised on June 12th, 14.00 – 15.30 CET, focused on heat exchanger technology, since heat exchangers are core equipment of sCO2 systems with an expectedly strong impact on Capital Costs and performance. Presentations can be downloaded from the SCARABEUS website: Link


This next event (5h in the series) will be held on September 28th , 14.00 – 15.00 CET, and will be focused on supercritical Carbon Dioxide expanders, which incorporate aspects of the past webinars such as aerodynamic design, turbomachinery seals, materials, etc. The lineup of presentations is as follows:

  • Which boundary conditions for CO2turbines?, Alberto Traverso (University of Genoa
  • Expander stage of an sCO2Companderfor 2 MW output power, Markus Sauerborn (Atlas Copco)
  • Benefits and design challenges of axial sCO2turbines, Stefan Glos (Siemens Energy)
  • Baker Hughes Design Experience with unfired Expanders, Andrea Paggini (Baker Hughes)


Download the complete agenda of the event from this link


Do not miss the opportunity to register here and book your seat for yet another very interesting event: Link