By Peter Wu
AUDI AG

(July 2, 2018) Behind the headlines and the bright lights of auto shows, automakers such as Audi continue to research and develop alternative energy sources and drivetrain systems. In addition to the well-known e-tron series of hybrid and electric vehicles, Audi has shown several concepts of its hydrogen-powered h-tron vehicles and currently offers several g-tron vehicles powered by Audi e-gas or compressed natural gas (CNG).

Audi operates research facilities throughout the world, but the center for electric, hydrogen fuel-cell and other drivetrain systems is in Neckarsulm, Germany.

It’s situated in the same complex that houses the Audi Forum Neckarsulm and the factories that manufacture the Audi A4, A5, A6, A7 Sportback, A8, and R8 Coupe and Spyder.

This R&D center is responsible for the hybrid technology currently available in vehicles such as the Audi A3 e-tron Sportback as well as glimpses of the future like the Audi e-tron Sportback concept that debuted in April 2017 and is scheduled for production in 2019. Audi engineers’ ongoing improvements in battery power and faster recharging systems will help ease the way to widespread electric mobility.

Audi engineers are also making meaningful improvements with hydrogen fuel-cell drivetrain systems. The company has been researching the technology for nearly two decades, with the A2H2 demonstrator introduced in 2004, the Audi Q5 Hybrid Fuel Cell in 2009 and, more recently, the Audi A7 Sportback h-tron in 2015 and the Audi h-tron quattro concept introduced at the North American International Auto Show in January 2016.

Hydrogen fuel cells create electricity by combining hydrogen fuel and oxygen, using that energy to power the electric motor or motors that drive the vehicle. Refilling the hydrogen fuel tanks takes just four minutes, about the time it takes to refuel a conventionally powered vehicle. One of the obstacles that fuel cell vehicles have to overcome is the size and weight of the hydrogen fuel tanks. To reduce the weight of the tanks, Audi engineers made the fuel tanks with an advanced polyamide material wrapped in carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP).

On the Audi h-tron quattro concept, three of these tanks are placed throughout the vehicle, with one close to where a traditional transmission would sit, one beneath the rear bench seat and one in the cargo area. These tanks are connected via an infrared interface that helps equalize pressure and temperature levels.

Improving the fuel cell itself is an area to which the engineers have devoted a great deal of resources. Working with Volkswagen and other technology companies in what is known as the HyMotion 5 project, the teams have been testing new materials to create the bipolar plates that separate the individual cells.

The goal is to make the fuel cell significantly lighter, smaller and more powerful, which can help with cold starting, service life and hydrogen consumption. The cost of production also can decrease by replacing the platinum currently used in fuel cells with the new materials.

The h-tron quattro concept unveiled in Detroit, Mich., in early 2016 is the first Audi fuel cell vehicle to incorporate quattro all-wheel drive and create the electrified quattro, thanks to a second electric motor that powers the rear wheels. Power comes from a fuel cell rated at 110kW and a 100kW lithium-ion battery that supplement drivetrain demands.

Synthetic & natural

In addition to the advances in fuel cell technology found in the h-tron quattro concept, Audi engineers and their energy technology collaborators have developed innovative fuel production methods. Grouped under the name Audi e-gas, these new fuels — also known as synthetic natural gas — are made with renewable materials instead of petroleum.

In the city of Werlte near Bremen in northern Germany, renewable natural gas is made by a process known as power-to-gas. Started in 2013, the first-of-its-kind production method starts by using electricity generated by wind turbines, which is fed into the power grid. That electricity is used to power an electrolysis plant that splits water into oxygen and hydrogen.

The hydrogen reacts with carbon dioxide from a biogas facility to produce the end product, e-gas. It is then fed into the region’s natural gas system and can be used to power the Audi A3 g-tron, Audi A4 Avant g-tron and Audi A5 Sportback g-tron — vehicles currently available to German buyers.

By taking on the challenge to broaden the mobility landscape, Audi has found viable solutions that are available today or will be in the near future. As a result of this research, the drivers of tomorrow should be able to choose from a wider range of drivetrain systems and fuel source options. While it may seem as though the future will be battery-powered, Audi has shown that viable options can compete on our roadways.