CSP Hybrid Power Plants: tools and facilities to explore the solar potential

Acknowledgments - The European project RESILIENT is greatly acknowledged for partially financing this activity. (www.resilinet-project.eu) - The Author wish to thank Matteo Campodonico and Alessandro Spoladore, graduate students of University of Genoa, for their contribution to this research activity. And all the TPG group.

Stefano Barberis – PhD Student

CSP Turbogas Hybridisation Among renewable technologies, Concentrated Solar Power (CSP) plants are seen as an attractive option to reduce pollutants and the emission of greenhouses gases (e.g. CO2). CSP technologies are based on the concept of concentrating solar radiation to be used for electricity generation within conventional power cycles. CSP Solar tower plants can achieve high operating temperatures of over 1000 °C, enabling them to produce hot air for gas turbine operation. Solarized hybrid Gas Turbines could be used in combined and mixed cycles, whose performances are analysed by the TPG thanks to a thermoeconomic approach.

THE IMPORTANCE OF STORAGE The integration of Thermal Energy Storage (TES) is one of the key advantages of CSP. In fact, TES allows excess solar energy to be harnessed from the Central Receiver System (CRS) during the daytime and stored, as thermal energy, for periods of insufficient solar supply, (cloudy hours, night…). In this way, the output of a CSP plant becomes dispatchable, allowing it to supply controllable power on demand to consumers. TES technologies are important to accelerate market penetration of CSP plants, overcoming the limitation due to the intermittence of the solar source. TES technologies were studied by TPG researchers thanks to their own thermoeconomic simulation tools (WTEMP – WECOMP – fig.1), analyzing the role of the storage and optimizing its size in all the possible CSP-TG hybrid power plants configuration [1] (fig.2).

Figure 1 – TPG Thermoeconomic Optimization Tools

Figure 3 – TPG Test rig layout with charging (green arrows) / discharging (red arrows) phases. In the particular the mGT test rig being modified for solar hybridization and a TES ceramic module

Moreover, only one regulating three-way valve (2) and one on/off three-way valve (3) are needed to control charging and discharging phases and they are set on two threshold temperature (Hot side/cold side). This result is achieved using the high-T orifice, which is a calibrated flange with a desired pressure drop. Indeed, valves (2)-(3) are subject to the compressor outlet temperature, at which conventional materials can be employed. Such a concept promises low cost and high reliability, despite introducing permanent pressure losses due to high-T orifice Before installation, the new test rig and the layout concept was modelled in the TRANSEO [3] simulation tool developed at TPG for dynamic and control analysis of gas turbine based energy systems

Figure 4 – Dynamic Analysis of Charging/ Discharging Phases of the TES

References [1] S.Barberis, M.Rivarolo, A.Traverso, 2014, “Thermoeconomic Optimization Of Csp Hybrid Power Plants With Thermal Storage “, ASME Paper GT2014-25137 [2] S.Barberis, M.Porta, A.N.T.Traverso, A.Traverso, A.M. Ferrari, A.Paraboschi, 2014 – “Thermal Storage For Solar Hybridized Gas Turbines” – ASME Global News, March 2014 – Vol.53, p.49 - 51 [3] A. Traverso, 2005, “TRANSEO Code For The Dynamic Performance Simulation of Micro Gas Turbine Cycles”, ASME Paper GT2005-68101.

HIGH T THERMAL STORAGE INNOVATIVE LAYOUT The TPG developed and patented an innovative layout and control scheme of a high temperature storage for Hybrid CSP-TG plants to avoid the need for any high temperature valves (800-900°C) , thus featuring lower costs and higher reliability, demonstrating it at laboratory scale [2]. The TES is made by five ceramic honeycomb modules (fig.4), and it is being integrated with a slip stream from the 100 kW mGT already present on site), while the solar input will be physically simulated with electric heaters.

www.tpg.unige.it University of Genoa DIME – Department of Mechanical Engineering

0 Bypass TES 1 Bypass Solar System 2 Charging TES 3 Full Discharging TES 4 Pilot Discharging TES

1 0 2 3 2 0 3 2 0 3 2 0 4 3 1

1 0 2 3 2 0 3 2 0 3 2 0 4 3 1

Th

erm

al Flo

w [

kW

] P

ow

er

[kW

]

El. Power

WTEMP

- Design Point Condition

- Exergetic, economic and

thermodynamic analysis

WECOMP

- Time Dipendent Condition

- Economic Scenario as Input

-Layout, Size and Operating

Thermoeconomic Optimization

ISCC – Integrated Solar Combined Cycle

On the Market Solution

SHCC – Solar Hybrid Combined Cycle

Innovative Solution

STIG - HyCSP – Solar Hybrid Mixed Cycle

Innovative Solution (Italian Patent Pending)

CRS

TES

2 3

High T Orifice

CC

1

HELIOSTATS

Fuel

Italian Patent Application

GE2013A000118

Figure 2 – Analyzed CSP-TG Hybrid Power Plants Layouts