The next step towards the long-term Audi goal of CO2-neutral mobility is being presented at this year’s NAIAS in Detroit in the form of the Audi h-tron quattro concept car – a striking SUV that uses a highly efficient fuel cell with an output of up to 110 kW, and a further on-demand power boost of 100 kW courtesy of a lightweight lithium-ion battery. The car can be fully refuelled with hydrogen in around four minutes, and is then ready to drive for up to 372 miles (600 km).
The Audi h‑tron quattro concept is closely related to the Audi e‑tron quattro concept, a purely electric SUV first showcased by the brand with the four rings at the 2015 Frankfurt Motor Show. Both are based on the second-generation modular longitudinal platform (MLB evo). This concept is especially flexible. For example, both cars use a virtually identical floor assembly despite their different technology.
The Audi h‑tron quattro concept presents the fifth generation of fuel cell technology from Audi and Volkswagen. Lighter materials reduce the weight and improve performance, responsiveness, service life and efficiency. With an efficiency rating in excess of 60 percent, the fuel cell now surpasses any combustion engine. The “stack” comprising 330 individual cells is housed in the forward structure.
The three hydrogen tanks are located beneath the passenger or luggage compartment but do not impinge on the interior. At a pressure of 700 bar, they store enough hydrogen for a range of up to 372 miles (600 km).
Every tank is made up of several layers – the inner tank from gas-tight polyamide is wrapped in carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP). Like a car with a combustion engine, refueling takes about four minutes.
Powerful booster: battery supplies up to 100 kW of power
Ideally complementing the fuel cell that develops up to 110 kW, there is a compact lithium-ion battery designed for optimum power output. The battery, weighing less than 60 kilograms, is located beneath the passenger compartment to optimise the centre of gravity. It supplies up to 100 kW of power, ample for a temporary, forceful burst when accelerating. When the car is braked it stores the recovered energy. With 550 Nm (405.7 lb‑ft) of system torque, the Audi h‑tron quattro accelerates from 0 to 62 mph in less than seven seconds; its top speed is governed at 124 mph.
The power from the fuel cell and the high-voltage battery drives two electric motors – one located on the front axle and with an output of 90 kW, the other on the rear axle and developing 140 kW. This concept makes the technology study an electrified quattro. An intelligent management system controls the interplay between them as appropriate for the situation, placing maximum emphasis on efficiency.
A heat pump for the interior air conditioning and a large solar roof that generates up to 320 watts, equivalent to adding up to 620 miles (1,000 km) to the range annually, also boost efficiency.
Zero global emissions with renewably produced hydrogen from the Audi e-gas facility in Werlte, Germany
According to the New European Driving Cycle its fuel consumption is around one kilogram of hydrogen per 100 kilometres (62.1 miles). The Audi h-tron quattro concept achieves not merely zero local emissions, but zero global emissions if the hydrogen it runs on has been produced with green power. The brand with the four rings realises this at the Audi e-gas facility in North Germany.
Since 2013 the world’s first power-to-gas plant has been using electricity generated by wind power to break water down into oxygen and hydrogen by electrolysis. In a further process, this gas reacts with CO2 to produce Audi e‑gas, or synthetic methane, for the Audi A3 g-tron and the A4 g-tron with CNG drive.
Many customers are already using the e-gas fuel card to buy Audi e‑gas via the existing natural gas network at conventional CNG filling stations, enabling them to drive almost CO2-neutrally. But in future it will be possible to tap into this hydrogen source so that fuel cell cars can run on this climate-friendly fuel.
Nerve centre for piloted driving: the zFAS
The Audi h‑tron quattro concept comes equipped with all the technologies that the brand has developed for piloted driving – radar sensors, a new kind of video camera, ultrasonic sensors and a laser scanner.
The driver assistance systems are now usually managed by spatially separate control units. In future, Audi will be implementing this function in a central domain architecture: All available sensor information is processed by a central driver assistance system (zFAS). It computes a complete model of the car’s surroundings in real time and makes this information available to the assistance systems and the piloted driving systems. They can assume driving tasks during parking or in stop-and-go traffic on motorways at speeds of up to 37 mph.
Audi has been performing pioneering work in this domain for many years and in 2017 will be taking this technology into production for the first time ever with the next generation of its Audi A8 Saloon.