By this time next year, the Audi A3 Sportback will be offered with a variety fuel-efficient powertrains ranging from diesel to the all-electric E-Tron, but perhaps the most interesting is the all-new G-Tron model, which uses Audi's innovative carbon-natural compressed natural gas called e-gas. Previously called A3 TCNG, we first heard about this technology last year, but now Audi has confirmed that this low-emission, sustainable-fuel will debut by the end of this year on the A3 Sportback G-Tron.

To create this e-gas, a plant in Werlte, Germany uses electricity to split water into hydrogen and oxygen. As hydrogen fuel cell vehicles become more popular, Audi says that this process could also be used to produce hydrogen fuel, but to create CNG, it mixes the hydrogen with carbon dioxide to create "synthetic methane." Since it is identical to the CNG available today, Audi's e-gas can be shipped and stored using the existing CNG infrastructure. Making the whole process even greener, Audi obtains the CO2 for this process from a nearby biogas plant, which would otherwise be released into the atmosphere.

Differentiated from the regular versions of the A3, the G-Tron features a pair of tanks under the rear cargo floor holding 15.43 pounds of CNG, which can power the car for almost 250 miles. What's more, the A3's conventional gasoline tank is still in place, giving the car an addition 560 miles of range. In total, that means the A3 G-Tron has a driving range of more than 800 miles. To run on both CNG and gas, Audi made changes to the car's 1.4-liter four-cylinder engine (including the turbo, cylinder head and fuel injection system) and catalytic converter.

It isn't clear how many G-Tron models Audi is planning to build, but the press release posted below says that its e-gas plant can provide enough fuel for 1,500 cars to travel about 9,300 miles (15,000 kilometers) per year.
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Ingolstadt, 2013-03-01

The new Audi A3 Sportback g-tron

-The new A3 Sportback g-tron is powered by the CO2-neutral Audi e-gas
-CO2 emissions of 30 grams per kilometer (48.28 g/mile)
-Total range of 1300 km (807.78 miles)

Audi is taking a large step towards sustainable mobility with the A3 Sportback g-tron. The compact five-door car, due to make its debut at the end of the year, is powered by the CO2-neutral fuel Audi e-gas. The fuel will be produced in the power-to-gas plant in Werlte, Germany. This new car innovatively combines ecological balance, economy and high-tech solutions.

The Audi A3 Sportback g-tron comes with the full gamut of Audi's technology expertise – from ultra-lightweight technology, and infotainment, to driver assistance systems. But first and foremost it showcases state-of-the-art CNG drive technology, starting with the fuel storage. Its two tanks under the luggage compartment floor can each hold seven kilograms (15.43 lb) of CNG at a maximum 200 bar pressure. In tune with the ultra-lightweight construction concept, each tank weighs 27 kilograms (59.52 lb) less than its conventional counterpart.

The tanks consist of a new type of matrix. The inner layer consists of gas-impermeable polyamide polymer, while a second layer of carbon fiber-reinforced polymer (CFRP) gives the tank its extremely high strength; a third layer of glass fiber reinforced polymer (GFRP) provides rugged protection against damage from the outside. High-strength epoxy resin is used to bind the fiber reinforced materials.

A second highlight of the Audi A3 Sportback g-tron is its electronic gas pressure regulator. This compact and lightweight component reduces the high pressure of the gas flowing from the cylinders down to around five to nine bar in two stages.

It ensures that the right pressure is always present in the gas rail and at the injector valves – low pressure for efficient driving in the lower speed range, and higher when the driver calls for more power and torque.

If the pressure in the tank drops below ten bar, the engine management system automatically switches over to gasoline operation. The Audi A3 Sportback g-tron is fully bivalent, i.e. its performance figures are identical in CNG and gasoline modes.

CNG provides a range – based on standard fuel consumption – of around 400 km (248.55 miles), with gasoline providing another 900 km (559.23 miles) if necessary; the total range is approximately on a par with an Audi TDI. Two displays in the instrument cluster provide the driver with up-to-date information on the fuel level in each of the tanks. The driver information system also displays the current fuel consumption based on the particular operating mode.

The two filler necks are placed under a common fuel flap. After refueling, and whenever it is very cold, the engine is started with gasoline initially, then it is switched over to natural gas as quickly as possible.

The engine is based on the new 1.4 TFSI. Key modifications relate to the cylinder head, turbocharging, injection system, and the catalytic converter. Developing 81 kW (110 hp) and 200 Nm of torque, the Audi A3 Sportback g-tron has a top speed of 190 km/h (118.06 mph), with 0 to 100 km/h (0 - 62.14 mph) taking eleven seconds. The five-door car consumes on average less than 3.5 kilograms per 100 km of CNG or Audi e-gas – the fuel that is generated from eco-electricity in the Audi e-gas project. CO2 tailpipe emissions are less than 95 grams per km (152.89 g/mile) in gas mode.

The greenhouse gas balance is even more attractive in a well-to-wheel analysis that accounts for all factors from the fuel source to the car's wheels. 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. 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 30 grams per km (48.28 g/mile).

Buyers of the Audi A3 Sportback g-tron will presumably obtain the e-gas at the public CNG refueling stations via an ecological accounting­ method, similar to the method currently in existence for obtaining eco-electricity.

With the e-gas project, Audi is the first automobile manufacturer to develop an entire chain of sustainable energy carriers. The start of the chain has electricity produced from renewable energy sources; the end products are hydrogen and the synthetic Audi e-gas. Construction of the world's first industrial plant to produce synthetic methane (e-gas) from CO2 and renewable electricity is almost complete in Werlte (Emsland district of Lower Saxony), Germany.

The Audi e-gas plant uses the renewable electricity in the first stage for electrolysis – splitting water into oxygen and hydrogen (Audi e-hydrogen), which could one day power fuel-cell vehicles. Because there is not yet a widespread hydrogen infrastructure, however, the hydrogen is then reacted with CO2 in a methanation plant to produce renewable synthetic methane, or Audi e-gas. Chemically speaking, this e-gas is identical to fossil-based natural gas. As such, it can 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 bidirectionally for the first time. 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, operated by power utility EWE. The CO2, which would otherwise pollute the atmosphere, is chemically bonded into the fuel at the Audi e-gas plant. The e-gas plant will annually produce about 1,000 metric tons of e-gas and will chemically bind some 2,800 metric tons of CO2. This corresponds roughly to the amount of CO2 that 224,000 beech trees absorb in a year.

The CO2-neutral e-gas from Werlte will power 1,500 new Audi A3 Sportback g-tron vehicles 15,000 kilometers (9,320.57 miles) every year. The power industry can also benefit from Audi's e-gas project, as it addresses the nagging challenge of how to store large quantities of renewable electricity produced from wind turbines and photovoltaic systems efficiently and irrespective of location. The electricity-gas cogeneration technology could significantly foster the expansion of renewable energies.

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    • 1 Second Ago
      • 2 Years Ago
      as long as the rich make more on oil prices noway well we have such a car in "america: "land of the rich no longer land of the free.
        • 2 Years Ago
        What a swell mindless chant that in America have been capable of running in CNG for years and in fact in the 70's with the OPEC oil embargo many cars were converted to run on CNG and there are some small fleets of local deliveery trucks that still use it. Its cheap and its clean burning, the most clean burning of the fuels. AND now we discovered the largest fields of natural gas in the world and are trying to extract, but are opposed by, wait for it..environmentalists who now FOR foreign oil rathern than domestic CNG. Bet you got some green chants to share with us too don't you?
          • 2 Years Ago
          Between 15%-20% of city buses nationwide run on CNG or LNG, as well.
      American 1st
      • 2 Years Ago
      Why can't Detroit do this?
      • 2 Years Ago
      Audi is investing in hydrogen infrastructure. ;)
      The MinisterDCX
      • 2 Years Ago
      Love to see a car like this made for the masses. The car will probably cost to much for the average person, which will minimize it's effect on the feul and environmental problem.
      • 2 Years Ago
      Wow. Wouldn't it be amazing to have a car that could go from coast to coast and not stop for fuel? I'd say that such a car is not too far off in the future.
      • 2 Years Ago
      0 to 60 in only 15 minutes as well!
        • 2 Years Ago
        Yeah, because turbo-charged Audis are renowned for their sluggishness. FAIL!
      • 2 Years Ago
      • 2 Years Ago
      Whats the price?
      • 2 Years Ago
      I just hope this one survives big oil trying to buy it out and destroy it. Pretty cool fuel concept.
      • 2 Years Ago
      Your range is either 250 or 560. you are using 2 different fuels and that is it. By the way how much does the CNG cost I bet it isn't cheap and it is everywhere.
        • 2 Years Ago
        CNG is WAY less than Gasoline, problem is filling stations, and in general range. There are kits to convert your car to bi-fuel but they cost like 5 grand, and there is no ROI with cost like that.
      • 2 Years Ago
      If you want to go a longer distance between fill ups just put a larger gas tank in your vehicle. They have been doing this with pickup trucks for years.
      • 2 Years Ago
      I'd like to know how Audi produces the hydrogen. There are no natural sources of hydrogen gas and the process of electrolysis of water to release ( not create) hydrogen and oxygen is very energy-intensive. Unless their source of energy is renewable and sustainable ( hydro, solar, or wind) the cost of the hydrogen in terms of CO2 production will be very high. If that is added to the admirable output of the automobile, the actual carbon footprint will be much higher than advertized.
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