A car can be considered CO2 neutral if the amount of greenhouse gas used in creating the fuel is balanced against the CO2 emitted by the vehicle in operation.

Even as automakers move to increase the number of battery electric vehicles (BEVs), fuel cell vehicles and hybrids, internal combustion technology is not standing still. In fact, Audi believes that the future will see a mix of propulsion technologies and that internal combustion can play a role in producing vehicles that have minimal CO2 impact on the environment. As shown by Toyota's recent announcement to slow-walk EVs, the industry is looking into other alternatives besides pure electrics to meet ever-tightening Corporate Average Fuel Economy (CAFE) standards and zero-emission mandates like those enacted by California.

Rupert Stadler, Audi's chairman, asserts that "the future of mobility will be multi-faceted." And while Audi will offer pure electrics, like the R8 E-Tron, officials from the company insist that the combustion engine still remains an important element in the overall picture. Key elements in this strategy include more fuel efficient gas and diesel engines using such advanced technology as electric forced induction and stop-start technology that includes shutting the engine off when the vehicle is coasting. Audi will also offer a unique dual-fuel A3 that uses both compressed natural gas (CNG) and gasoline power that promises a range of around 750 miles in an A3.

Beyond the approach of upgrading the hardware, Audi is also looking at vehicle fuels themselves as a means to reduce carbon emissions. The company believes that an internal combustion car can be considered CO2 neutral if the amount of greenhouse gas used in creating the fuel is balanced against the CO2 emitted by the vehicle in operation. The argument goes that a BEV is only CO2-free if its electricity comes from nuclear, hydro, wind or solar sources and actually contributes to CO2 emissions if the electricity comes from a coal- or gas-fired generator. Following this line of reasoning to its logical conclusion, Audi is now involved in several projects to make ethanol, diesel and natural gas that uses CO2 in the production process.

Matt DeLorenzo is the former editor-in-chief of Road & Track and has covered the auto industry for 35 years, including stints at Automotive News and AutoWeek. He has authored books including VW's New Beetle, Chrysler's Modern Concept Cars, and Corvette Dynasty.

The most futuristic of these fuels is what Audi calls e-gas, a form of compressed natural gas produced through electrolysis and methanization. In partnership with SolarFuel, Audi has built a plant in northern Germany that uses wind power and electrolysis to create hydrogen from water. The hydrogen itself could be used in fuel cell cars. However, since the necessary infrastructure to deliver hydrogen to the automotive fleet is still being built, a second process has been added to methanize the hydrogen by using CO2 and water to create synthetic gas, a fuel that can be delivered through the existing natural gas lines and fueling stations. The CO2 used would come from organic waste that normally would enter the atmosphere through decomposition. This plant will produce 1,000 tons of methane per year starting in 2013 using 2,800 tons of CO2 in the process, which would, by Audi's calculation, give 1,500 Audi A3 Sportbacks enough fuel to run 15,000 km per year carbon neutral.

The second major fuel front is biofuels, principally ethanol and diesel, both of which can be distributed through the current fossil fuel infrastructure. Audi has teamed with Joule, a Bedford, Mass., based company to build a plant that uses bacteria to produce fuels that can be burned in conventional internal combustion engines. Called e-ethanol and e-diesel by Audi, this process combines waste water (which can be brackish or saline), bacteria, CO2 and photosyntheses to create a form of ethanol. The advantage here is that the ethanol produced is not food or plant based, but rather is created by the bacteria. A slightly more complicated and costly process can be used to create a diesel variant, which is purer than fossil-based diesel. Audi says that both fuels are economically viable in a market that currently commands $100 per barrel oil.

Audi A3 TCNG infographic

According to Heinz Hollerweger, Audi's Head of Development, Total Vehicle, in order for this approach to succeed, it will take new thinking on the part of vehicle producers and more importantly, those writing emission laws. "It means a new broad perspective, an open mind," Hollerweger maintains. "In the past, the focus was entirely on the emissions coming directly from the vehicle. Now we are analyzing the entire product lifecycle and orienting ourselves toward the principle of a closed-loop circuit where the negative environmental impacts are preferably avoided." It appears to be a sound approach, however, the questions remain, will it fly with the EPA and California regulators?

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