Performance evaluation of an industrial borehole thermal energy storage (BTES) project - Experiences from the first seven years of operation

• Borehole thermal energy storage (BTES) is a technology which allows for both seasonal and short-to-medium-term storage of thermal energy and which can be used for both heating and cooling. This makes BTES of special interest to many industries. However, post-implementation evaluations of largescale industrial BTES are scarce. The BTES at Xylems production plant in Emmaboda, Sweden is one of the worlds largest BTES systems for storage of industrial excess heat. In this paper, the BTES at Emmaboda was evaluated with respect to how it was integrated and how it has performed during its first seven years of operation. The BTES consists of 140 boreholes, 150 m deep, and heat for storage is mainly recovered from two high-temperature ovens and the foundry ventilation air. So far, the highest heat extraction and BTES efficiency (19%) took place in the storage systems sixth full year of operation, when roughly 2200 MWh and 400 MWh were injected into and extracted from the storage respectively. One main reason extraction is not higher is that the quantities and/or the quality of the excess heat for storage are lower than estimated, thus hindering the storage from reaching the necessary temperatures for heat extraction. (C) 2019 Elsevier Ltd. All rights reserved.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

Borehole thermal energy storage; Industrial excess heat; BTES performance; Temperature distribution; Geothermal technology; Thermal conductivity

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