In a research cooperation, the IET supports the company Hydrotaurus GmbH in the development of a reciprocating engine with CO2 as the working medium, which is always in the supercritical state. The machine is to be used to convert low-temperature thermal energy (low-temperature heat) into mechanical energy as much as possible.

During a work cycle, the working medium exchanges mechanical energy with a hydraulic system, in which hydraulic oil is brought from a low to a high pressure level. In an idealized way, the changes in the state of the working medium during the cyclic process result in a rectangular shape in a state diagram in which the pressure is plotted against the specific volume (p,v-diagram).

At the given temperature levels of heat supply and heat release, the geometry of the reciprocating piston machine must be designed in a way that the area inscribed by the cyclic process is as large as possible. In the figures, two cyclic processes are shown as examples in a p,v and a T,s diagram (the latter plots temperature versus entropy).

Concentrated Solar Power (CSP) plants can play an important role in the energy supply mix in the twenty first century. Nevertheless, the Levelized Cost of Electricity (LCoE) of CSP has not attained the level targeted except for few installations in exceptionally good locations. As of today, many ongoing research projects aiming at enhancing the efficiency of the power block and reducing the associated costs are based on supercritical CO₂-technology. However, relatively high ambient temperatures, typical in regions characterized by high solar irradiation, remain the Achilles heel of supercritical 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 pure CO₂ (31°C), hence not allowing to adopt condensation (Rankine) cycles with expectedly higher efficiencies. This issue stems as an intrinsic critical 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, this project analyses a modified working fluid whereby carbon dioxide is blended with certain additives to enable condensation at temperatures as high as 60°C whilst, at the same time, still withstanding the required peak cycle 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.

There are two main areas of research in this project: The first is the identification of the optimal additive, which would reduce the size and increase the efficiency of the power block. The second is the development of tailored heat exchanger designs, particularly for the air-cooled condenser, to operate with the innovative fluid as these are key enabling components for the proposed technology. Both actions will lead to a significant reduction of CAPEX and OPEX with respect to conventional CSP technologies.

Objectives

The project aims at developing and demonstrating an innovative power cycle based on blended CO₂ for CSP-applications, yielding higher efficiency and lower cost. 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 respect to state-of-the-art steam cycles, thus exceeding the reduction achievable with standard supercritical CO₂ technology.

The project demonstrate the innovative fluid and newly developed heat-exchangers at a relevant scale (300 kWth) for 300 h in a CSP-like operating environment.

CO2Refinery is a doctoral college at TU Wien and offers excellent scientific research, combined with a multi- and interdisciplinary curriculum.

The primary objective of this four-year work programme is to undertake cutting edge multidisciplinary research and development to make a step change in understanding of Supercritical CO₂ based power generation systems’ technology and its potential to enable a step change in thermal energy power cycles to be a major contributor to achieving the 2050 zero emissions targets while providing specialised training for 15 doctoral researchers to help establish the backbone of an important industry. The technical objectives of this research are:

1. Develop advanced models and design tools that enable the optimal integration of sCO₂ power systems components for various thermal energy sources and end use applications
2. Develop accurate prediction tools for the simulation of transient operation of sCO₂ power cycles and investigate innovative concepts of control and optimisation of operation
3. Develop innovative methods to enhance aerodynamic and mechanical performance, reliability, and operability of key system components
4. Develop advanced modelling and experimental methods that enable selection and development of materials, coatings and manufacturing techniques

ISOP is an EU-funded project (Call: HORIZON-MSCA-2021-DN-01) which consists of four research WPs and requests funding for 15 Doctoral Candidates for a total of 540 person months working on an ambitious plan to advance the sCO₂ power cycles technology beyond the state-of-the-art. The project aims to contribute to the EU agenda on European Research Area by training “a new generation of creative, entrepreneurial and innovative early-stage researchers”, who can face future challenges and to “convert knowledge and ideas into products and services for economic and social benefit”. In addition, support to and compliance with the United Nation’s Sustainable Development Goals will be at the heart of the training of the doctoral candidates and the scientific and economic outcomes of this.

Project partners

1. CITY UNIVERSITY OF LONDON UK
2. UNIVERSIDAD DE SEVILLA ES
3. INSTITUTO SUPERIOR TECNICO PT
4. UNIVERSITY OF STUTTGART DE
5. NUOVO PIGNONE TECNOLOGIE SRL IT
6. TOTALENERGIES SE FR
7. MEGGITT UK LIMITED UK
8. EMPRESARIOS AGRUPADOS INTERNACIONAL SA ES
9. FUNDACION ANDALUZA PARA EL DESARROLLO AEROESPACIAL ES
10. SOFTINWAY SWITZERLAND GmbH CH
11. TU WIEN AT
12. EUROPEAN TURBINE NETWORK Belgium
13. INERCO INGENIERIA, TECNOLOGIA Y CONSULTORIA, SA Spain
14. EASY ENERGY CONSULTING & TECHNOLOGY SA CH
15. ROSSWANG GmbH DE
16. CESKE VYSOKE UCENI TECHNICKE V PRAZE Czechia
17. DOOSAN SKODA POWER SRO Czechia

Contact

Univ.Prof. Dipl.-Ing. Dr.
Markus HAIDER
Phone: +43 1 58801 302 08
E-mail: markus.haider@tuwien.ac.at