Thermo-economic analysis, optimisation and systematic integration of supercritical carbon dioxide cycle with sensible heat thermal energy storage for CSP application

Dhinesh Thanganadar,Francesco Fornarelli,Sergio Camporeale,Faisal Asfand,Jonathon Gillard,Kumar Patchigolla

doi:10.1016/j.energy.2021.121755

Abstract

Integration of thermal energy storage with concentrated solar power (CSP) plant aids in smoothing of the variable energy generation from renewable sources. Supercritical carbon dioxide (sCO2) cycles can reduce the levelised cost of electricity of a CSP plant through its higher efficiency and compact footprint compared to steam-Rankine cycles. This study systematically integrates nine sCO2 cycles including two novel configurations for CSP applications with a two-tank sensible heat storage system using a multi-objective optimisation. The performance of the sCO2 cycles is benchmarked against the thermal performance requirement of an ideal power cycle to reduce the plant overnight capital cost. The impacts of the compressor inlet temperature (CIT) and maximum turbine inlet temperature (TIT) on the cycle selection criteria are discussed. The influence of the cost function uncertainty on the selection of the optimal cycle is analysed using Monte-Carlo simulation. One of the novel cycle configurations (C8) proposed can reduce the overnight capital cost by 10.8% in comparison to a recompression Brayton cycle (C3) for a CIT of 55 °C and TIT of 700 °C. This work describes design guidelines facilitating the development/selection of an optimal cycle for a CSP application integrated with two-tank thermal storage.

Highlights

Renewable energy technologies including concentrated solar power (CSP) plants have a significant role to play in keeping the global average temperature increase below 2 C according to Paris agreement
Thanganadar et al [14] compared the techno-economic performance of recompression, partial cooling and partial heating cycles integrated with two-tank TES and central tower CSP plant for ten different boundary conditions, concluding that partial cooling cycle remains economical for all the boundary conditions investigated
The optimal heat addition DT of an ideal power cycle is about 270 C for a turbine inlet temperature (TIT) of 600 C, which increases to about 420 C for a TIT of 700 C

Summary

Introduction

Renewable energy technologies including concentrated solar power (CSP) plants have a significant role to play in keeping the global average temperature increase below 2 C according to Paris agreement. CSP plants are capital intensive, but with essentially no fuel cost, the levelised cost of electricity (LCOE) principally depends on the capital cost and the regional solar resource [1]. The US Department of Energy (DOE) SunShot program has a goal to reduce the LCOE of CSP plants below 6¢/kWh [2], requiring a power block target performance of >50% efficiency with dry cooling at 55 C ambient temperature at a unit cost of 550 C, and compact plant footprint [2,4]

HT HTR IC LCOE LMTD LT

Optimal heat addition DT for an ideal power cycle

Performance of sCO2 cycles

Monte-Carlo uncertainty analysis

Conclusions