A Pumped Thermal Energy Storage Cycle with Capacity for Concentrated Solar Power Integration

Conference · Mon Oct 14 04:00:00 EDT 2019

DOI:https://doi.org/10.1109/OSES.2019.8867222· OSTI ID:1575190

Farres-Antunez, Pau ^[1]; McTigue, Joshua Dominic P ^[2]; White, Alexander J. ^[1]

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1. University of Cambridge
2. National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Pumped thermal energy storage (PTES) is a grid-scale energy management technology that stores electricity in the form of thermal energy. A number of PTES systems have been proposed using different thermodynamic cycles, including a variant based on a regenerated Brayton cycle that stores the thermal energy in liquid storage media (such as molten salts) via heat exchangers. This has several advantages, including the possibility to consider hybrid 'solar-PTES' systems employing technology developed by the concentrated solar power (CSP) industry. Such a hybrid system could charge the same hot stores using either solar energy or off-peak electricity (e.g, from nearby wind farms), increasing the capacity factor of the plant while employing the same heat engine during discharge. In this paper, two different configurations of solar-PTES systems are proposed and studied numerically: (i) a configuration in which an existing CSP plant is retrofitted with a Brayton heat pump, and (ii) a configuration in which a new hybrid plant uses the Brayton cycle both for charge and discharge. In both cases, the need to absorb and reject heat at conditions close to ambient temperature requires the Brayton cycle to incorporate intercooled stages at the cold side of the cycle. On the other hand, the intercooling process increases the minimum temperature of the cold stores, meaning that widely available and nonflammable antifreeze solutions (such as water-ethylene glycol) may be used as the cold storage medium.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1575190
• Report Number(s): NREL/CP-5500-74135
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
47 OTHER INSTRUMENTATION
concentrated solar power
energy efficiency
heat exchangers
pumped thermal energy storage
thermodynamic cycle analysis