Volvo will supply 300 hybrid buses for an extensive test next year. Volvo\'s hybrid technology, known as Parallel Hybrid, is based on a diesel engine that generates electricity which is fed to lithium-ion battery pack. A controller than controls the supply of electricity to an electric motor that propels the bus\'s wheels.TFL already operates 172 hybrid buses in London.London is going to be a much cleaner city if a test of 300 hybrid buses in the British capital will prove successful. Next year Volvo will supply the 7700 hybrid series buses equipped with its advanced i-SAM parallel hybrid system. The buses will be the famous red double-deckers (and they won\'t be painted green).Traffic for London (TFL), the authority for all transport in London, estimates that it will reduce emissions by at least 30% and will bring a least a 30% reduction in fuel consumption. Sounds levels will be reduced as well by 3 decibels and emission of other gasses will also be reduced.