Customer :


Euro Tunnel

Key Figures:
Tunnel lenght: 50,5 km
More than 9 millions passangers per year
Goods tons per year : 18 millions
Tunnel depth : 40m undersea

Performance SWAC:
Energy savings from 30%to 40%.


The Channel Tunnel, began operating in 1994, linking France to United Kingdom is the longest tunnel undersea of the world. More than 9 million passengers are crossing the sea each year, and 18 million tons of goods. The whole tunnel is equipped with a huge cooling system requested for trains proper functioning. However, Eurotunnel, the owner company, is facing up to a high energy consumption and thus very high cost. Consequently, the company is looking for new air conditioning solutions.

Project description

Throughout this study Deprofundis wants to assess the feasibility of implementing a SWAC (Sea Water Air Conditioning) system to guarantee a lower energy consumption. By decreasing the Channel tunnel cooling system energy consumption, the final goal is to drop down energy cost.

Foresee the SWAC size is a key point of this project. Two different approaches will be done: one solution is to replace cold produced on English coast (Shakespeare Cliff) the other one on French coast (Sangatte). This study will also compare potentials others solutions to Sea Water Air Conditioning system, as well as assess savings done by a cooling system with a lower energy consumption.

Finally, we will define which place will be the most appropriated to connect a new air conditioning system to the tunnel.


Firstly, Deprofundis supported by Eurotunnel studied precisely the current system as reference. Then, all others criteria mentioned below were analyzed to assess feasibility:

  • Bathymetry, to evaluate pipes’ length.
  • Thermal gradient, to define temperature contrast during a year to be take into account.
  • Ocean currents and swells, to establish the kind of structure to use and define pipes stability.
  • Area geology and geography, to assess trenchless drilling method and estimate the related budget.
  • Draw up energy consumed compares to energy produced ratio calculations
  • Economic data such as electricity cost in France and United-Kingdom
  • Environment observations, and SWAC implementation’s ecological impacts.


As the outcome of the study, Deprofundis considers a savings from 30 to 40%. The project of Sea Water Air Contioning system is currently under discussion with Eurotunnel.

n avec Eurotunnel.