Heat energy from a shallow geothermal system in Glasgow, UK: performance evaluation design

Abstract

This study reports on the actual energy and economic performance of a water source heat pump recently installed and operated at a Glasgow Subway Station using subsurface water ingress to provide heating and domestic hot water. This follows from a previous publication (Hytiris et al., 2016) that detailed the empirical measurements and design of a heating system designed on the basis of a fifteen-month monitoring period of the water flow and temperature. The perennial water flow at a relatively high temperature enabled the system to operate more efficiently than a typical heat pump system with boreholes or trenches. The performance of the water source heat pump has been monitored for a four-month period and the coefficient of performance as well as energy saving is reported in the present study. The findings of this study indicate the energy, carbon and financial benefits of the heating system, but also highlight key issues during the operation in such a demanding underground environment. Further renewable heat potentials for the rest of the subway network and opportunities to commercialize the excess heat energy output are explored.

The Performance of an ASHP System Using Waste Air to Recover Heat Energy in a Subway System

“…The total energy consumption for the five radiators over that period was 0.904 MWh (0.904 MWh = 904 KWh/7 days = 129.14 KWh per day. 129.14 kWh/16 h = 8.07 KW) [9]. With the readings from the ASHP's energy monitoring system, it is concluded that the energy input for this station has been reduced by almost 70%.…”

“…Clean Technol. 2019, 2, 00 2 performances [8,9]. The latter study also highlighted the lessons learnt following installation and the potential for this system to be scaled up in similar environments.…”

“…Strathclyde Partnership for Transport (SPT) who operates the Glasgow Subway, were keen on finding ways to exploit its wasted resources within the underground system. They already use wastewater via a water source heat pump (WSHP) in the northern part of the subway at St George's cross Station, providing heat and domestic hot water (DHW) for the Station's ticket booth [9]. Due to the nonexistence of water flux in the southern part of the subway system (to the south of river Clyde- Figure 1), the ASHP trial installation was focused on the following five stations: Bridge Street, West Street, Shields Road, Cessnock and Ibrox.…”

“…The appropriateness of underground railway systems for the use of ground-source heat pumps was reviewed by [7]. Several feasibility studies demonstrated that an ASHP can be positioned within such a closed, yet well ventilated environment with promising performances [8,9]. The latter study also highlighted the lessons learnt following installation and the potential for this system to be scaled up in similar environments.…”

Recovery and Valorisation of Energy from Wastewater Using a Water Source Heat Pump at the Glasgow Subway: Potential for Similar Underground Environments

“…The station's old heating system was based 100% in electricity (electric fired radiators), consuming 10 kW without counting for the DHW. The WSHP requires a 4 kW input covering the DHW as well [10]. The payback period for this trial setup considering all the installation costs is projected to be 12 years.…”