Pumped heat electricity storage: potential analysis and orc requirements
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Date
2017-09
Publication Type
Conference Paper
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no
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Abstract
The rising share of renewable energy sources in power generation leads to the need of energy storage capacities. In this context, also some interest in thermal energy storages, especially in a concept called pumped heat electricity storage (PHES), arises. One possible design of such a PHES system consists of a compression heat pump, a thermal storage and an organic Rankine cycle (ORC). The present work analyses the general thermodynamic potential and limits of such a system and deals with the unusual requirements for the ORC. The potential analysis starts with the optimal case of combining two Carnot cycles with irreversible heat transfer. It is found that the efficiency of the entire process increases with increasing storage temperature and in general roundtrip efficiencies up to 70 % are predicted. Afterwards the cycles are transferred to cycles that are more realistic by considering technical aspects and a hypothetical working fluid which is optimized by an inverse engineering approach. This leads to lowered roundtrip efficiencies, which now, decrease with increasing storage temperatures. In a second step the specific ORC requirements as part of a PHES are considered, emphasizing the working fluid parameters. Especially, the use of a latent thermal energy storage leads to an ORC design differing from common (e.g. geothermal) applications. It is shown that the efficiency of the ORC and of the entire process strongly depends on the superheating at the expander inlet; here, the superheating must be held as small as possible, contrary to ORCs using common heat sources.
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Publication status
published
External links
Book title
4th International Seminar on ORC Power Systems
Journal / series
Volume
129
Pages / Article No.
1026 - 1033
Publisher
Elsevier
Event
4th International Seminar on ORC Power Systems (ORC 2017)
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
pumped electricity heat storage; fluid selection; inverse engineering; endo-reversible thermodynamics
Organisational unit
09696 - Bardow, André / Bardow, André