Thermal effect of a borehole thermal energy store on the subsurface

Abstract

Background: The thermal effect on the subsurface of a large borehole thermal energy store (BTES) has been investigated by coupling measured rock properties with an enhanced FEFLOW simulation.

Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

“…This is partly because faster flow through the system is assumed, which achieves higher rates of energy transfer, this being partly a consequence of the larger diameter of the borehole. It is also partly a consequence of the thermal diffusivity of Carboniferous mudstones in Britain being 20 assumed to be higher than the typical measured value (from Mielke et al 2014) for the rocks utilized for the Crailsheim subsurface heat exchanger. An additional factor, recently recognized (Lanini et al 2014), is that the design of this project was non-optimal from the point of view of efficiency of energy storage.…”

“…This is even though the running costs of BTES systems are relatively low and they will maintain something like their planned seasonal storage capacity for many years, although the effectiveness of particular designs will decrease over time as increasing proportions of the stored heat progressively conduct (or are transported by groundwater flow) so far away that they cannot be recovered by the borehole heat exchanger (see e.g. Mielke et al 2014). 30 The possibility of repurposing future disused shale gas wells in the UK for geothermal energy supply has been noted previously, for example by GEL (2015a) and Bridge et al (2015), albeit with few technical details provided.…”

“…For this particular project, groundwater flow is contributing to dissipation of stored heat (Mielke et al 2014) . These values are summarized in Table 1, along with the corresponding parameter values for the proposed shale gas well lateral-based BTES configuration.…”

Effect of sedimentary facies and geological properties on thermal conductivity of Pleistocene volcanic sediments in Tokyo, central Japan

“…To cite cases in Europe, a GSHP with dynamic thermal energy storage was installed in hard rock (mica gneiss, Silurian sediments and Ordovician sediments) in Norway (Liebel et al 2012), a borehole thermal energy store was installed in fractured Triassic sedimentary rock with fractures in Germany (Mielke et al 2014) and a GSHP system was installed in a chalk layer in London, UK (Busby et al 2009;Arthur et al 2010). The main lithology in which GSHP systems are installed is fractured sedimentary rocks in Europe, which are countries in the process of introducing GSHP systems.…”

Subsurface energy storage: geological storage of renewable energy—capacities, induced effects and implications

“…Experience from both open well systems and using borehole heat exchangers exists, however mainly in the lower temperature range (e.g. Mielke et al 2014).…”