Compact Transmission Lines – The Power Tunnel

As the previous articles in this blog described: Underground compact gas insulated lines transfer high power in a safe way and with low losses. In this particular blogpost we want to show you specific tunneling laying solutions for this technology.

There are different opportunities for the underground laying of compact transmission lines (CTL). Either they can be directly buried in the ground – like at our project in Kelsterbach at the Frankfurt airport (see video on the web), or they can be installed in a tunnel. At first glance, the construction of a tunnel brings additional effort, but the advantages of such a solution are convincing, so that a tunnel – like in existing reference projects proven – can be the technique of choice.

What reasons are in favor for a tunnel installation?

The extensive insulation measures, which are necessary for the directly earth laid aluminum lines, are redundant at tunnel installation.

A space-saving arrangement of the lines in the tunnel could reduce the necessary route width significantly.

Tunnel installations allow an extension of the transmission capacity through additional subsequently laid systems, without complex earthworks.

An accessible tunnel enables easy access to every section of the transmission line, at every required time.

The outstanding characteristics of the compact lines – they don’t pose a fire hazard and could be touched while being in operation - allows a simultaneously use of the tunnel for other purposes.

Power and traffic on the same route

The last named characteristic is the basis to think about a combination of car and train tunnels with compact high power transmission lines. Having no exposure to the surrounding environment – whether human or material – the energy tubes could be integrated without risks in consisting or planned infrastructure (e. g. infrastructure tunnels).

Optimized concepts for the energy tunnel

For tunnels which are especially built for power transmission, many different construction forms are possible. From small, not accessible tunnels, to trough-solutions or to fully drilled tunnels (e.g. with pipe jacking), which can cross mountains or rivers, there exist a wide range of technologies.

Siemens is working together with expert partners from civil and mechanical engineering on optimized concepts for such tunnel solutions. The best solution in each case depends on many criteria, e. g. defined routing, condition of the overcoming terrain, length of the transmission route or the need for a future extension of the transmission capacity.

Optimized total costs depend on the individual case

The higher costs for a tunnel construction could be offset by taking total costs of ownership into consideration. Besides the cost of material and the amount of work, other factors like small land consumption, low life cycle costs or the utilization of the area above the line, have to be considered.

The topic on compact power transmission lines remains hopefully exciting for you.

Get more information on this year’s Hannover Fair end of April where we are presenting GIL/CTL at the “Integrated Energy Plaza” in hall 27. Furthermore, I will take part on the “Life Needs Power” Forum with a presentation on Wednesday 27, 2016.

Stay tuned and learn more about compact transmission lines (CTL) in my next article or talk to me on the Hannover Fair. Looking forward to interesting discussions!