New passenger tunnels were required to be built between existing platforms at Kennington Station to cope with increased passengers numbers once the Northern Line extension to Battersea and Nine Elms becomes operational. The tunnels had to be completed within a 16-week window to minimise impacts on the network and works were required 24/7. Unfortunately there was insufficient power supply available from the station and therefore a large external diesel generator was proposed.
The generator had to be located very near to residential properties and there was concern over the air quality impacts this would have. The generator that had been sourced met the local requirements for engine emissions, however this was still a potential health concern.
There were limited practicable options for further reducing emissions since the generator could not be changed and installation of retrofit technologies to capture pollution would have been too expensive and taken too long.
The project supplied the residents closest to the generator with fans and air purifiers, so that they may avoid opening the windows during the summer heat. In addition a cleaner burning fuel (Green D) compared to red diesel was procured.
Green D is a biodiesel made from a combination of waste fats from the cooking industry and also plant oils. It uses an additive so that it performs just as well as red diesel and no adjustments are required to the engine or pipework.
Biofuel has been shown to reduce emissions of harmful pollutants such as nitrogen oxides (NOx) and particulate matter, as well as the carbon footprint being almost 90% lower than that of red diesel.