LONDON OLYMPICS ENERGY CENTRES
Park and the adjacent retail park, was only part of the task. Equally importantly, when the Games are over the energy centres will continue to be developed and run by Cofely’s specialist business unit, Cofely District Energy, for the next 40 years to provide the Park’s legacy buildings and surrounding developments with low carbon heating and cooling. The challenge is that, whilst the energy demands of the Park’s venues during the Games are known, the future energy demands of the site’s legacy buildings are less well defined.
Modular design The approach has been to design and build the energy centres in a modular format to enable plant to be added in the future, once the legacy loads are known. The utility had two years from the start of construction to build the two energy centres and the site- wide network of 16km heating and cooling pipework. Both energy centres are housed in
buildings designed by architect John McAslan & Partners. The centres are large, brown rectangular boxes, wrapped in a mesh of pre-rusted, perforated cladding panels with a 45m tower at one end housing the boiler flues. The rusty façade was not installed until the key items of plant had been positioned on the building’s steel frame. To enable future plant to be installed, sections of the building’s cladding have been designed to be easily removed. Inside the giant Kings Yard energy
centre, the modular approach to the scheme is immediately apparent. Adjacent to the two, huge 20 MW dual-fuel gas/oil fired boilers is the space for three additional boilers. All the pipework and flues are in place so that boilers can be added in the future with the minimum of disturbance, while the system remains live. Similarly, adjacent to the 3.3 MW gas-fired combined heat and power (CHP) engine, pipework connections are already in place in four empty bays for further units, if required. In summer, when the demand for
heating is less, heat recovered from the CHP units can be used to drive a 4 MW absorption chiller. Even if the absorption chiller is not running, cooling can still be provided by two, 7 MW ammonia-based chillers. Again, space has been allocated for an additional future chiller. The chillers reject heat through five roof-mounted cooling towers. During the Games the main demand for cooling will come from the International
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Broadcast Centre and the Handball Arena. After the Games, the Handball Arena is set to become a community sports centre, but the big and, as yet, unanswered question is: what will happen to the Broadcast Centre, particularly in terms of utilising the installed cooling capacity? To ensure cooling can be supplied
efficiently, even under light load conditions, the chilled water circuit includes a giant cylindrical chilled water buffer vessel. The 750 cu m vessel increases the capacity of the chilled water system by 4.7 MWh, so that when loads are low the ammonia or absorption chillers can run uninterrupted, charging the vessel. A similar system operates on the hot water circuit, with the 27.5 MWh capacity buffer vessel intended to allow the uninterrupted operation of the CHP engine and the system’s giant boilers. A third tank contains treated make-up water for the hot and chilled water system. The enormous tanks are situated outside the building, adjacent to its eastern façade. The plant’s current installed capacity is
46.6 MW heating, 18 MW cooling and up to 6.68 MW of electrical power, depending on loads. When all the plant is in place the energy centre will have the potential to generate up to 122.5 MW heating, 25 MW cooling and 10.02 MW of electrical power. In contrast to Kings Yard, Stratford City
energy centre has no spare cooling capacity and less future capacity for heat-generating plant because the energy centre was built primarily to meet the established cooling and heating loads of the new Westfield Shopping Centre and its associated office
Pipework Installation of the heating and cooling mains
One thing was for certain: the 16km network of district heating and cooling pipework that link the two energy centres with the Olympic venues had to be in place for the Games. This achievement was only possible in the two years from commencement of construction to operation because the entire installation was modelled in 3D (see Design: 3D Modelling). There was insufficient
time to wait for the venues to be constructed, and for the site to be landscaped, before installing the heating and cooling mains. Instead the mains were installed in sections as areas became available. It was a challenging
operation with mains passing beneath railway tracks and over bridges to reach all the Park’s venues. Over time these sections were gradually joined as further sections of the site became available, until the network was completed. The mains are constructed
from pre-insulated carbon- steel pipes comprising 50mm of polyurethane insulation enclosed in a polyethylene protective outer sleeve. The pipes have a built-in leak detection system. The pipes were installed in 12m lengths, at diameters up to 400mm, and welded together. Once the leak alarm cables were joined, a muff was wrapped around the pipe joint and insulation
injected into the void created by the muff. The pipes are buried so
that the top of the pipe is at least 1m below surface. By using buried pipework, network losses are low, with a temperature drop of around 1C per kilometre. The advantage with the site is that there were very few buried utilities to avoid. However, on the down side, because the site was still being reconfigured the ground was not always at the finished level. As a result, some pipes over 2m had to be installed above the ground on temporary supports until the final ground level was established.
August 2011 CIBSE Journal 19
A view of part of the Olympic Park with the athletics stadium in the foreground. The Kings Yard energy centre can be seen by the waterway in the top left of the picture
ODA 2008
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