Wolsburg fuses petrol and diesel technology to create C02-neutral engine
15 December 2006

Volkswagen has just unveiled what it claims is the internal combustion engine of the future. Called the Combined Combustion System (or CCS for short), it mixes the most favourable characteristics of both petrol and diesel technology to make one low emissions, high efficiency power unit which runs on synthetic biofuel. Mounted in the nose of the recently facelifted Touran, the engine was introduced to the motoring press this week.

The CCS engine recognises the possibility that, in order to meet tightening emissions standards and ever higher demands for fuel efficiency, car makers may have to abandon conventional petrol and diesel engines in favour of a new type of motor altogether. VW's take on this engine of the future is an advanced four-cylinder based on the German car maker’s upcoming 2.0-litre common rail diesel engine due to head into production in 2008. It was designed to meld the homogeneous combustion and low nitrous oxide emissions of a typical small capacity petrol powerplant with the self ignition and low fuel consumption properties of a modern day diesel – the aim being to combine the best attributes of each.

Using the latest piezo injector technology from German electronics specialist Bosch, the CCS engine is able to begin the combustion process within each cylinder much earlier than in existing diesels, which tend to start shortly after the piston reaches top dead centre. The fuel mixture that enters each of the CCS' cylinders is fully vaporised and ignites over a larger area than it might in a conventional engine. in much the same way as a modern day direct injection petrol unit does. This early firing reduces the build up of nitrous oxide and particulates caused by non-vaporised fuel and hot spots within the cylinder – both big drawbacks of today’s diesel engines according to Christoph Kohnen, who was closely involved in the development of the new engine at Volkswagen’s R&D centre located in Braunschweig, Germany.

Because the fuel mixture is ignited over a longer period, the CCS unit also proves more economical. No hard and fast figures have been put forward just yet, but Volkswagen claims that consumption is improved by around five per cent on the European combined cycle test, which involves a mixture of city and motorway driving.

To ensure the CCS process could be achieved, Volkswagen has worked closely with German based Choren Industries to develop a new synthetic fuel. This fuel is a CO2-neutral biomass mixture containing no petrol or diesel, but rather created using forest or industrial waste as well as bio-degradable rubbish, animal waste and specially planted crops. Unlike other propulsion technologies being pushed at the moment, it does not require any dramatic alteration to existing infrastructure. “The fuel can be delivered through normal filling stations,” says Kohnen.

Volkswagen is predicting the CCS engine could be ready for inclusion in production cars from early next decade, if current initiatives to make synthetic fuel available on a large scale come to fruition. Together with the prototype we drove, VW also has turbocharged versions on test beds producing output figures similar to those of existing diesel units. The next step is to combine the CCS engine with electric drive to create a hybrid that Kohnen predicts will set a whole new standard for achievable environmental sustainability.

Greg Kable

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