Ground heat exchange potential of Green Infrastructure

Anil Yildiz,Ross A Stirling

doi:10.1016/j.geothermics.2022.102351

Abstract

Both Green Infrastructure and Ground Source Heat Exchangers provide opportunities to significantly improve the resilience and sustainability of our built environment. This work explores the thermo-hydrological response of a vegetated Sustainable Drainage System under physically simulated heat injection conditions using a soil column of 1800 mm diameter and 950 mm height in a heavily-instrumented lysimeter. A range of field testing scenarios (thermal load and cycling) were applied under natural, external ambient conditions. Soil temperature during heat injection was also simulated numerically by solving a transient heat conduction equation with a finite difference modelling scheme. The developed model was validated using measurements from the lysimeter setup which then enabled numerical experiments into the effects of varying hydrological regimes to be performed. Results of the field testing showed that heat injection propagates a temperature change only at deeper layers, while the temperature of shallow layers are still governed by the atmospheric conditions.

Highlights

Energy demand for space heating and cooling accounts for nearly a third of the final energy demand in the 28 member states of the European Union, the majority of which comes from residential buildings, supplied with energy generated from fossil fuels (Fleiter et al, 2017)
This study aims to present the behaviour of simulated, both physically and numerically, heat injection into a purpose-built at-scale Green infrastructure (GI) component
Numerical modelling framework presented in this study considers the heat injection as an incoming flux from the heat exchanger, i.e. heating cable in the field setup, and a one-dimensional heat transfer

Summary

Introduction

Energy demand for space heating and cooling accounts for nearly a third of the final energy demand in the 28 member states of the European Union, the majority of which comes from residential buildings, supplied with energy generated from fossil fuels (Fleiter et al, 2017). The inevitable need to reduce fossil fuel consumption has led to an increased need to rapidly develop renewable energy solutions, including the use of multiple sources. Geothermal energy, which has been documented to be utilised in more than 80 countries (Lund and Boyd, 2016), is an alternative to fossil fuels for electricity generation, direct heating, and indirect heating and cooling via ground source heat pumps (GSHP) (Self et al, 2013). Horizontal GHEs buried in shallow trenches offer a viable alternative solution for smaller demands, as trench installation requires a lower budget (Wu et al, 2015), a large area of land is needed (Go et al, 2015)

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Conclusion