Under the motto of “Audi balanced mobility”, Audi has committed to attaining neutral CO2 balance across the entire mobility chain. The Audi e-gas project, a milestone along this route, is capable of simultaneously solving several pressing problems faced by the sustainable energy-supply industry. In the process chain clean power, hydrogen and methane are produced: three key sources of energy for future mobility. Included as a component of Audi’s plans is production of a natural gas vehicle for their A3 range.
Starting in 2013, Audi will begin series production of TCNG models whose engines – derived from TFSI units – will be powered by e-gas, Audi’s preferred name for synthetic natural gas. The A3’s four-cylinder TFSI engine and the exhaust system’s catalytic converter were designed with natural gas in mind.
Via the “balanced cycle method” – similar to the purchasing of green power – A3 TCNG owners should be able to fuel their vehicles with wind energy starting in 2013. When a driver refuels with e-gas, the corresponding amount of renewable energy required to produce this e-gas is fed into the grid.
The volumetric density of e-gas is equal to that of fossil-based natural gas and is thus lower than premium unleaded. Similarly to natural gas, the combustion of e-gas also creates far less CO2 than premium unleaded does. Concerning the e-gas project, this means that CO2 emissions are very low not only in the overall picture (well-to-wheel), but also at the exhaust pipe (tank-to-wheel). Not one gram of CO2 is emitted via the exhaust pipe which would not have been consumed during the manufacture of e-gas. In other words, there is a closed CO2 cycle between the fuel’s manufacture and its combustion, arguably earning the carbon-neutral tag.
The high octane rating of approx. 130 RON for natural gas, biomethane and also for e-gas facilitates a high compression ratio in the turbo engine – which ensures high efficiency. The A3 TCNG, which store the methane at a pressure of 200 bar, offer enough capacity for long drives. The Audi A3 TCNG also boasts a bivalent (bi-fuel) configuration: if the natural-gas tanks run empty and there is no CNG station nearby, the vehicle can run on conventional gasoline with no drop in performance.
This article compiled using information from an Volkswagen-Audi press release.