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Thermal properties of Triassic Sherwood (Bunter) Sandstone Group and Mercia Mudstone Group (Keuper Marl) lithologies
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 2nd Geoscience & Engineering in Energy Transition Conference, Nov 2021, Volume 2021, p.1 - 5
Abstract
The thermal properties of rocks and soils are of great importance to the design of renewable energy systems including geothermal wells and underground energy storage systems. However, the UK has variable geology/lithologies and poor availability of published thermal properties data linked to Group, Formation, or litho-facies creates uncertainty.
The testing of 59 samples of Sherwood Sandstone Group sandstone (Liverpool, NW England) found the average intrinsic thermal conductivity (λh sat) is 3.2 W/mK, thermal diffusivity of 0.14 m2/day and estimated volumetric heat capacity 2.0 MJ/m3/K. From a technical feasibility perspective, the Sherwood Sandstone aquifer is a very good candidate for large-scale Open loop GSHP, free-cooling, and Aquifer Thermal Energy Storage (ATES) technology deployment.
The measured average partially-saturated horizontal thermal conductivity of Mercia Mudstone Group argillaceous/mudstone facies (Newport, S Wales) is 1.9 W/mK, diffusivity is 0.09 m2/day, and estimated volumetric heat capacity of 1.9 MJ/m3/K, based on 29 samples. The MMG is a good candidate for Closed-loop GSHP and Borehole Thermal Energy Storage, but low permeability and yield, and soluble mineral content (gypsum) makes it a poor candidate for ATES. Where the MMG overlies the SSG it provides natural thermal insulation which will reduce ground-side heat losses and enhance whole-system efficiency.