The queue to get your car on to the train for the Channel Tunnel may raise the temperature in the family vehicle this summer, but at least the tunnel itself will be cool – and Eurotunnel is paying a lot less to keep it that way. That’s because Eurotunnel has installed a new cooling system in the tunnel itself which has resulted in a 33% cost saving.
The amount of energy saved is 4.8 GWh, which amounts to around EUR 500,000. Eurotunnel has had four sustainability certificates from the Carbon Trust already, and this initiative has earned them a fifth. The new system decreased the company’s carbon footprint by 9%.
Largest Cooling System in Europe
When installed, the cooling system was the largest in Europe. The refrigerant used was Honeywell’s Solstice zd. This has very low potential for global warming. The chillers were from Trane, and these were already in use elsewhere to cool major infrastructure locations and large buildings.
The HVAC challenge is certainly significant. Without cooling, the high-speed trains passing through the tunnel between Folkestone and Calais would generate enough heat to push the tunnel temperature up to 35 degrees Celsius. That’s the top temperature that the trains can run at while providing optimal service. Obviously, that level of heating is too close to the limits to be acceptable. The aim is to keep the ambient temperature about 25 degrees, and this is achieved by the new system.
The Trane chillers are very large – and in the Channel Tunnel installation there are four of them. Each one has a capacity of 2,500Kw to 14,000 Kw. These machines are around 10% more efficient in terms of energy use than the nearest competitor that can operate at this tonnage. The first two, at the French end near Sangatte, came into operation about eighteen months ago. The two at the English end were added by the end of 2017.
Lowering Carbon Footprint While Maintaining Performance
The Honeywell refrigerant used in the system is part of their new line of products, branded as “Solstice”. These aim to help customers achieve a lower carbon footprint while maintaining performance. The refrigerant used in the tunnel is the non-flammable Solstice zd, which is based on the company’s hydrofluoro-olefin (HFO) technology. The global warming potential is 99.9% lower than R22, the previous refrigerant used in the tunnel. In fact, the new product has the lowest global warming index of any non-flammable refrigerant available. It was originally designed for centrifugal chillers used to cool very large buildings and for high-temperature heat pumps.
The dramatic reduction in global warming potential shows what can be achieved if radical new technology is adopted for HVAC systems. While the Trane chillers and Solstice zd refrigerant are clearly for major projects, the principle holds true for smaller installations. We’re just beginning to see products being developed that can slash energy use and costs without using harmful chemicals or degrading the performance of HVAC systems. So it could be a case of the Channel Tunnel today, city office blocks tomorrow.