Archive for category: News

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

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

Abstract

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

Abstract

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!

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 22^nd, 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 5^th 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 12^th, 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 (5^h in the series) will be held on September 28^th , 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

Turbo Expo is the flagship conference in the field of turbomachinery for power generation and aircraft and marine propulsion. The conference gathers ~2500 professionals annually, who meet to share the latest development of the scientific and industrial communities through technical, panel and tutorial sessions as well as keynote talks. The conference is organized by the International Gas Turbine Institute of the American Society of Mechanical Engineers.

Turbo Expo has been one of the preferred venues to disseminate the outcomes of the SCARABEUS project, as communicated in previous years on this website, and this year has not been different.

In the first day of this year’s conference, held at the Hynes Convention centre in Boston (MA), Prof. David Sánchez organised a panel session to introduce the “Supercritical CO₂ Projects in the International Community”. Seven projects funded by the Horizon 2020 and Horizon Europe programmes of the European Commission were presented in this session, followed by a very interesting panel discussion. The SCARABEUS project broke the ice, setting the stage for the other projects to complete the landscape of supercritical Carbon Dioxide research in Europe. The kind support of Eric Clementoni (Bechtel Marine Propulsion Corporation), stepping forward as improvised Co-Chair of the session due to the absence of Dr. Jason Wilkes (Southwest Research Institute) is gratefully acknowledge.

Intro slide and session schedule of panel on international Supercritical Carbon Dioxide projects

Panellists of session 31-31 (from left): Rafael Guédez (KTH), Silvia Trevisan (KTH), Lorenzo Arcangeli (Baker Hughes), Alberto Traverso (University of Genoa), Renaud Le Pierres (Meggitt), David Sánchez (University of Seville)

The main outcomes of the SCARABEUS project were also presented at another panel session, “Supercritical CO₂ Research & Development”, organised by Renaud Le Pierres (Meggitt, UK), where Prof. David Sánchez (Dissemination Coordinator of the SCARABEUS project) shared the stage with distinguished speakers from Europe and North America: Vittorio Michelasi (Baker Hughes, Italy), Nathan Weiland (National Energy Technology Laboratory, USA), Aaron McClung (Southwest Research Institute, USA), Ty Neises (National Renewable Energy Laboratory). With respect to the session above, this session had a much wider scope, not only discussing today research efforts but also looking into the foreseen needs of the energy market in the future and how supercritical Carbon Dioxide technologies can possibly fulfil them.

In addition to these panel sessions, a number of technical papers were presented at ASME Turbo Expo by the SCARABEUS partners. The team at University of Seville presented a very interesting paper discussing how to optimise the design and operation of Air-Cooled Condensers to enhance part load performance with minimum impact on Capital Costs:

• Rodríguez-de Arriba, F. Crespi, D. Sánchez, L. García-Rodríguez, 2023, Assessment of Part-load Operating Strategies of Supercritical Power Cycles Using Carbon Dioxide Mixtures in CSP Plants, Including Air-Cooled Condenser Optimisation (GT2023-103665), Presented at Turbo Expo, June 26-30, Boston (MA).

The team at City, University of London presented their latest research on the development of axial turbines for Carbon Dioxide mixtures. In this paper, the authors compared the impact of adding certain dopants on the flow path of large axial turbines working with Carbon Dioxide and supercritical inlet conditions:

• I. Salah, M. T. White, A. I. Sayma, 2023, A Comparison of Flow Path Designs for Axial Turbines Operating with Pure CO₂ and CO₂ Mixtures, Presented at Turbo Expo, June 26-30, Boston (MA).

These technical papers are currently being processed by the editorial services of ASME and will be made available in Open Access in the next months. Keep an eye on the online digital collection and on this website for further information.