London Underground Ground-water Cooling System

Project Background & Objectives

My Report will focus on the London Underground and the technology that has been put in place to help resolve the problems of over heating through-out the network. The project involves underlining all the major problems that lead to the high temperatures on the underground and the effects it has on the passengers. Further research would involve working out the best possible solutions whilst making them environmentally friendly and most importantly effective.

The primary objectives of the project are to develop a system that can be put in place on the underground to try and provide a means of cool air to the stations and trains. Also to ensure the passenger comfort needs are met to a suitable and safe standard. Long term objectives are to have the first air conditioned trains and furthermore have entire tube lines fully fitted with air cooling systems.

The current status of the project currently sees the first cooling systems fitted at London Victoria Underground station and also air vents fitted on trains. This project began in the summer of 2006 and saw the first groundwater cooling system put in to place and tested at Victoria. This trail was considered a success and was thus further continued throughout 2007.

The Sustainable Technology Issue

The sustainable technology issue that has been installed is an efficient cooling system which keeps the tunnels and trains cool and is environmentally friendly. The technology is energy efficient as it mainly uses water, which is a renewable energy source.

The technology is known as ground-water cooling. It works by taking water that is stored deep below the surface in rocks or from the rivers Thames, Colne & Lee which all fall in to the London Groundwater Basin. The average temperature of the water tends to fall around 12 degrees Celsius. This is the pumped through heat exchanges, which works by passing the water over a heat exchange and extracting it as cold air which is distributed through vents in to the station. The trains also can be kept cool with vent fans that have been built in to the roofs of carriages pulling in cool air to improve passenger comfort during their journey.

Technical Alternatives & Consequences

As with any objectives that are put forward, there will be some sort of alternatives which provides different solutions. Energy as we know is now not free and at times not always in demand. Groundwater cooling is partially dependant on the levels of water that are available. So what other backup alternatives are there, especially for other Underground networks that don’t geographically locate by rivers? The first is having the use of platform screen doors to completely separate the train environment from the station. A second trialled alternative is having under platform air exhaust systems has been a great success as these draw hot air out from the point on the train where heat is generated. Using the piston effect of trains to move air around is also important, coupled with the use of large extraction fans. These have been tried on the Underground network in Singapore. Lastly another alternative that has been put forward by Metro-Net works by freezing the chalk layer below the clay strata and then using the cold conditions to cool adjacent areas by a series of heat exchangers. This technique is known as ‘artificial ground cooling’ and has been used before in other locations with great success. The technology is suitable in London as the geological conditions are ideal.

Further alternatives have seen the start of a trial at Stockwell where a borehole will be drilled to the water aquifer below London where cold water will be extracted and used via a heat exchanger to cool warm air, the station ventilation fan network will be upgraded, temporary portable industrial fans will be trialled at Seven Sisters and Chancery Lane stations this summer and if successful will be rolled out at other stations, a new mechanical chiller is being installed at Oxford Circus station, a new ventilation shaft is being installed at Liverpool Street station to extract warm air while a condenser unit at Charing Cross will redirect heat to outside, rather than within. The first air-cooled trains are not due to arrive in service until January 2010.

As with any proposed ideas, there must be some sort of possible consequence, groundwater cooling as previously mentioned used water as its primary source of energy, and as long as the water tables remain high, this will continually be able to work. With the underground being such an old network, achieving new installations may be a challenge.

Political & Financial Issues

The London Underground plays a major role in providing transport for the City and is mainly operated by Transport for London. One of the prime responsibilities for the undergrounds falls to London Mayor, Ken Livingston. He is responsible for maintaining the network and ensuring high standard for commuters. As with any proposed improvements there is going to be someone somewhere who doesn’t feel the ideas may be beneficial. Is taking water form rivers such a good idea, especially with all the problems of global warming. Should we be putting so much responsibility in to natural resources when they can be unpredictable? Ultimately it’s a positive risk hat has been taken. Politically there can be little opposition into something that can only provide benefits to millions.

The London Underground is on the world’s biggest and busiest underground and such a project is undoubtedly going to cost a substantial amount of money. A press release from London mayor Ken Livingston said that within the next few years up to £150 million would have been spent on improvements, but around £10 Billion would need to be the total spent to meet London's transport needs, now and in the future.

Sustainable Development issues from a National or Global perspective

Groundwater Cooling technology is vastly being considered as one of the most effective ways of urban underground cooling, not just in London, but across the world. In Mexico City, there are some issues of using groundwater cooling and these involve the water supply itself. For example many cities may not have the capabilities to maintain the quality & quantity of water and with the example of Mexico City, unsustainable exploitation of aquifers leads to tremendous problems and the constant deficit of the water balance has strongly lowered the water table, resulting into land subsidence and ecological problems.

From a National perspective, there is always a new sustainable development project happening, especially in the capital. But what's important is that the projects are taking in to consideration what is meant by sustainable development. Ensuring that the environment and those living around it is not effected is paramount. So is tampering with the water table and potential polluted waters meeting those requirements. In my opinion no and this is where, if any potential effects might occur, as mentioned there are a number of alternatives, this might be the cheapest & easiest but is it the safest?

Conclusion

To summarise its clear to see that groundwater cooling of the London Underground is being considered as the primary way to achieve cooling. It uses a renewable source of energy and is easy to implement. But on the other hand, it’s playing with nature and relying on clean amounts of water. I believe that this technology will be seen more and more around the globe, but as I say, all sustainable development projects can be further sustained and with other alternatives I’m confident that London and other major underground networks will achieve their goal of effective cooling systems.

References

Kessell, C (2005). Cooling the Tube. Retrieved January 12, 2008, from www.theiet.org

(2007). Keeping London Undergound cool. Retrieved January 13, 2008, from www.londonlogue.com

Esteller M.V., & Diaz-Delgado C. (2002). Environmental effects of aquifer overexploitation. Retrieved January 13, 2008, from www.surf.salford.ac.uk