Going for energy efficient gold

The organisers of the London Olympics were determined that 2012 would see the greenest Games ever. An example of this commitment to renewable and energy-efficient technology was a state-of-the-art Energy Centre constructed to provide power, heating and cooling across the whole Olympic Park for the entire duration of the Games – and beyond. Robert Williams reports.

The Energy Centre became operational in October 2010 and began providing an early legacy of sustainable energy across the site, helping to reduce the carbon emissions of the Olympic Park well before the Games. It was much more efficient than having individual systems in each building and saved an enormous amount of energy that would normally have been lost in transporting it long distances from traditional power stations.

The building provided power, heating and cooling systems across the Olympic Park for the Games, the venues and the Olympic Village and for the new buildings and communities that are being developed. A significant proportion of the 20 per cent renewable energy target was met by this facility which includes a biomass boiler that uses woodchip as fuel to generate heat, and a natural gas powered combined cooling, heat and power plant.

The project is the largest energy centre scheme to be built so far in the UK and features a gas-fired Combined Cooling Heat & Power (CCHP) plant to capture the heat generated by electricity production. It also includes biomass-fired boilers that use sustainable biomass fuels, such as woodchip, to generate heat and deliver low-carbon energy. Together with a second energy centre, built in Stratford City, they served the heating, cooling and electricity requirements of the Games venues and other facilities.

The Energy Centre was designed to be a community landmark in the tradition of London’s Battersea and Bankside power stations. Part of the Centre is housed in a renovated Edwardian sweets factory, which was the only original building retained from the Olympic Park site as it was prior to construction. The Kings Yard Edwardian building was renovated to visually integrate with the surrounding listed buildings. It reaches 45m from the ground at its highest point.

The Centre has a flexible modular design, so that extra capacity and new technology can be added when demand increases once the area is further developed after the Games.

Both the energy centres will serve the new metropolitan development in east London after the 2012 Games. About five new neighbourhoods are being planned for development in the future. The environmental and economic benefits include a huge reduction of carbon emissions – while the design of the Centre is both flexible and sustainable to allow it to be adapted as technology progresses.

The Kings Yard plant is equipped with two 20MW hot water boilers, three 3.5MW bio-boilers, two 7MW electric chillers and one 4MW absorption chiller. It has five cooling towers. Boilers in the Energy Centre use natural gas as feedstock. Base demand for heat during winter is met through the bioboilers that use sustainable biomass, such as woodchips and pulp, as feedstock.

Now that the Games are a pleasant and fading memory, the Centre will continue to support the permanent Olympic venues as well as the new buildings and communities that will develop after 2012.

CHP efficiency gains

Combined heat and power is energy efficient technology. It provides a means to substantially reduce fuel, or ‘primary energy’, consumption without compromising the quality and reliability of the energy supply to consumers.

CHP integrates the production of usable heat and power (electricity), in one single, highly efficient process. It generates electricity whilst also capturing usable heat that is

produced in this process. This is a significant contrast with conventional methods of generating electricity where vast amounts of heat is wasted. For example, in coal and gas fired power stations, up to two thirds of the overall energy consumed is lost in this way, often seen as a cloud of steam rising from cooling towers.

Their relative sophistication means that the overall efficiency of CHP plants can reach in excess of 80 per cent at the point of use. This compares with the efficiency of CCGTs, which in the UK ranged between 49 per cent and 52 per cent over the period 2006 to 2008. Coalfired plants fare less well with an efficiency of around 38 per cent.

CHP plants generally meet local energy needs; certainly for heat, also power and increasingly for cooling. They normally avoid additional efficiency losses of around 7 per cent incurred through transmission and distribution of electricity through the National Grid and local distribution networks – as energy is lost travelling long distances to reach its end user. When taking account of these losses, the respective efficiencies of both coal and CCGT plant fall further at the point of use.

The efficiency benefits of CHP provide a range of wider advantages. Delivering the same energy more efficiently, using less fuel in the process, reduces energy costs, enhances security of energy supply and helps mitigate our dependence on imported fuels. As we move towards a lower-carbon future CHP also presents the opportunity to secure costeffective reductions in CO2 emissions.

Today’s CHP systems are based predominantly upon existing, proven power generation technologies, including steam turbines, gas turbines and reciprocating engines used the world over to generate energy. This use and adaptation of existing technology not only contributes to the relatively low cost of CHP, but also ensures that it is a proven and reliable technology, capable of delivering an immediate impact in transforming our energy system.

The City of London plans to generate about 25 per cent of its power requirements locally by 2025 through the construction of energy centres. It also plans to reduce the costs associated with fossil fuels and carbon emissions by 60 per cent by then. The Olympic Park Energy Centre will play its part, powering about 10,000 homes in the long run. An educational and historic Information Centre is also planned for visitors within the Energy Centre. n