Turning segmental tunnels into sources of renewable energy

Abstract

Geothermal energy is a universal low-grade renewable energy source and can be built into any engineering structures that provide large interface areas with the ground. There are already a number of case studies on retrieving geothermal energy from tunnels lined with sprayed concrete, but this paper presents a new system for segmental tunnel linings. Following a field trial in Germany it has been successfully installed in a new high-speed railway tunnel in Austria to supply a municipal building with heating energy. The paper demonstrates how subsurface urban structures can contribute both to sustainable city planning and the provision of decentralised renewable energy.

The design of thermal tunnel energy segments for Crossrail, UK

“…More recently, thermal structures have been built in TBM Tunnels. Zü blin AG and Rehau AG & Co have championed this development with a field test in the Katzenberg high-speed rail tunnel in Germany followed by the Jenbach twin track highspeed rail tunnel in Austria, which incorporated a 54 m long demonstration section with thermally activated segmental tunnel lining equipped with heat exchange pipes (Franzius and Pralle, 2011). These cross-linked polyethylene (PE-Xa) pipes were connected to a heat pump in the utility centre building to provide hot water and space heating.…”

“…The paper by Franzius and Pralle (2011) discusses embedding plastic absorber pipes in the precast concrete tunnel segments of a conventional metro to collect heat from the adjacent ground. However, at Crossrail the primary heat source is the waste heat rejected from trains, and the surrounding ground is the secondary source.…”

Energy piles: site investigation and analysis

“…Typical examples are bored or pre-fabricated piles, retaining walls, diaphragm walls, tunnel walls, basement slabs, basement walls and soil anchors (Brandl, 2006, Adam and Markiewicz, 2009, Franzius and Pralle, 2011. Although energy foundations are considered to be new relative to other forms of renewable energy technologies such as wind, solar or biomass (Abdelaziz et al, 2011, Peron et al, 2011 they have now been installed in a number of engineering structures throughout the world (Boennec, 2008, Gao et al, 2008, Laloui, 2011.…”

“…However, the thermal response testing regime performed by Brettmann and Amis (2011) indicates that the test methodology remains valid for larger diameter heat exchangers. Franzius and Pralle (2011) carried out a thermal response test on the 'Katzenbergtunnel' high-speed rail tunnel wall in Germany prior to its opening. Although neither the calculation method used to determine the thermal conductivity results nor the actual value of calculated thermal conductivity are described in detail by Franzius and Pralle (2011), the resulting calculated heat flux from the test was used in the design of a demonstrator project in Jenbach, Austria which is described in detail in Frodl et al (2010).…”

Editorial

“…Hunting for greener transportation, energy harvesting is a way of reducing the footprint of infrastructures (Duarte and Ferreira, 2015;Franzius and Pralle, 2011). This process consists of capturing, converting and distributing small energy variations.…”