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NEWS
GENEVA MOTOR SHOW: Audi A3 gases up
A3 Sportback g-tron revealed as Audi embraces compressed natural gasAudi has revealed a compressed natural gas (CNG) version of its all-new A3 Sportback, which goes on sale here in May, that’s claimed to emit about a third of the greenhouse gases of a Toyota Prius hybrid.
Unlikely to ever be sold in Australia, the A3 g-tron will be one of five world debuts to be staged by the Volkswagen luxury brand at next week’s Geneva motor show, alongside the A3 Sportback e-tron and RS Q3.
The g-tron goes on sale in Europe late this year, powered by a new 1.4 TFSI four-cylinder engine that can run on petrol, CNG or CO2-neutral Audi ‘e-gas’, which will be produced in a world-first power-to-gas plant that is nearing completion at Werlte in Germany.
When running in gas mode, the small five-door hatchback is claimed to consume less than 3.5kg of Audi e-gas or more widely available (in Europe) CNG, equating to CO2 emissions of less than 95g/km.
However, measured on a well-to-wheel basis – including fuel source, vehicle production and operating emissions – Audi says the g-tron emits less than 30g/km of CO2 when running on e-gas, because the e-gas plant uses CO2 to produce fuel.
“When the A3 Sportback g-tron is powered by Audi e-gas, no more CO2 is released than was chemically input in its production beforehand, creating a closed loop,” says Audi.
“When the energy required to build the e-gas facility and wind power generators is included in a comprehensive analysis, CO2 emissions are still less than 30g/km.”
Audi says CNG provides the g-tron with a driving range of around 400km, with petrol providing another 900km, equating to 1300km between refills – about the same as the TDI diesel version, which emits far more CO2.
The modified 1.4 TFSI engine – which features revised cylinder head, turbocharger, injection system and catalytic converter designs – produces 81kW/200Nm, which is enough to propel it to 100km/h in a respectable 11 seconds and a 190km/h top speed.
As with traditional dual-fuel LPG systems, during start-up and in cold conditions the engine runs on petrol before being switched over to natural gas.
The g-tron, which is fitted with all of the standard A3’s infotainment and driver aid technologies, comes with fuel gauges for both the petrol and gas tanks, and two filler necks under a common fuel flap.
Two gas tanks positioned under the cargo floor can each hold 7kg of CNG at up to 200 bar of pressure, each weighing a claimed 27kg less than a conventional equivalent thanks to a three-layer matrix construction.
The latter comprises an inner layer formed by a gas-impermeable polyamide polymer, a second layer of carbonfibre-reinforced polymer (CFRP) and a third layer of fibreglass-reinforced polymer (GFRP) to protect it from damage, all bonded together by high-strength epoxy resin.
Audi says it expects g-tron drivers to buy e-gas at public CNG refuelling stations via “an ecological accounting method” similar to the way in which Europeans currently purchase ‘green’ power.
In what it claims makes it the first car-maker to develop an entire chain of sustainable energy carriers, the e-gas initiative starts with electricity produced from renewable energy sources and ends with hydrogen as a by-product of the synthetic methane it calls Audi e-gas.
The e-gas plant uses renewable electricity to split water into oxygen and hydrogen via electrolysis. The German maker says in future this ‘Audi e-hydrogen’ can be used to power fuel-cell vehicles but, for now, the hydrogen is reacted with CO2 in a methanation plant to produce renewable synthetic methane.
The e-gas is chemically identical to fossil-based natural gas and can therefore be distributed to CNG stations via the natural-gas network.
“Thanks to the power-to-gas process, the electricity grid and gas network are being linked bi-directionally for the first time,” says Audi.
“Until now while you could generate electricity from gas, the reverse was not possible. The Audi e-gas plant therefore paves the way for tapping into the natural-gas network with its huge capacity as a storage and transport system for hitherto excess electricity capacity.”
The CO2 used in Audi’s e-gas plant is a waste product from a nearby biogas plant that would otherwise have been released into the atmosphere, and is chemically bonded into the fuel at the Audi e-gas plant.
Audi says its e-gas plant will produce about 1000 metric tons of e-gas – enough to power 1500 A3 g-tron vehicles for 15,000km every year.
In addition, it says its electricity-gas cogeneration technology will chemically bind 2800 metric tons of CO2 every year – roughly the same as the amount of CO2 that 224,000 beech trees absorb in the same period.
Audi also claims the e-gas project will foster the expansion of renewable energies within the power industry by addressing “the nagging challenge of how to store large quantities of renewable electricity produced from wind turbines and photovoltaic systems efficiently and irrespective of location”.
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Written byMarton Pettendy
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