What do you buy if you want a car that is sporty, practical, efficient, but also good for the environment? Usual answer would somehow involve electric power and car of choice would either be a full electric car or a hybrid. However, Audi is ready to offer something different. Company is preparing a new A4 Avant g-tron, which is scheduled to launch in late 2016. This car is powered by natural gas or climate-friendly Audi e-gas and can be completely CO2-neutral, if desired.
Audi already has a car powered by gas in shape of A3 Sportback g-tron. But A4 Avant g-tron model is supposed to be even more impressive. Company says it will be sporty, yet efficient and extremely economical. Many of us have heard about gas powered cars and some of us might have actually had them, as they were not very rare. Usually they were conversions from a simple petrol engine, made in order to save money spent on much more expensive petrol. Unsurprisingly, Audi’s idea about gas powered car is very similar.
The A4 Avant g-tron is powered by a powerplant is based on the new 2.0 TFSI engine, which features an advanced, highly efficient combustion process. It produces 125 kW (170 hp) of power and 270 Nm of torque. Of course, some changes had to be made to accommodate new fuel. The pistons and valves have been specially modified for gas operation and allow for an optimal compression ratio.
There is also an electronic controller, which reduces the high pressure of the gas flowing from the tank to the engine. Its task is to reduce pressure from as much as 200 bar to a working pressure of 5 to 10 bar in the engine. This electronic controller is set to be very precise in response of how much power does the driver demands from the car at specific moment – the higher the pressure, the more power and torque.
The car in this configuration is extremely efficient and economical. But its fuel efficiency is, of course, measured differently than that of normal petrol-powered car. A4 Avant g-tron consumes less than 4 kilograms CNG (compressed natural gas) per 100 kilometres, which, according to the company, costs around 4 euros.
Since the tank can take up to 19 kilograms of gas, car has a range of 500 kilometres. When gas tank is becoming empty, car switches to gasoline operation and can cover an additional 450 kilometers. Audi says that with such an impressive combined range A4 Avant g-tron is comparable to cars with TDI engines. However, CO2 emissions are less than 100 grams per km., which is especially important in those countries that tax cars by their emissions.
Car will also start on petrol when it was recently refilled or it is cold, but will switch to gas as soon as possible and driver is always informed about levels of both of these fuels. Car uses four cylindrical CNG tanks as a compact module in its rear end. They are protected from the damage by sheet steel shells with tensioning straps holding them in place. Although the entire unit with the 25 litre gasoline tank is made to be as compact as possible, spare wheel is eliminated. For this reason battery is also moved to the engine bay.
Tanks themselves are rather innovative as well. They have an operating pressure of 200 bar at 15 degrees Celsius. Because Audi wants them as light as possible, tanks are made from various composite materials in three layers. Inner layer is a gas-tight matrix of polyamide.
Middle layer is made of a composite winding of carbon fibre-reinforced polymer and glass fibre-reinforced polymer, which provides a lot of strength for the tank. The outer layer is pure glass fibre-reinforced polymer. Its purpose is visual inspection aid, because it turns milky white in damaged areas. Each tank is tested at 300 bar during production, but the actual bursting pressure is much higher, which makes it a very safe system.
Now the interesting part – how can this car be completely CO2-free? Secret is in Audi’s e-gas. e-gas is a synthetic methane produced from water and CO2 with the help of green electricity in multiple power-to-gas plants. Audi is the leader in this field, operating the world’s first industrial-scale power-to-gas plant in Werlte. Now company also procures e-gas from other facilities.
Of course, driving to Audi’s facilities to fill up the tanks would be a big problem. But it is not necessary – drivers get a car, which serves as both a payment and balancing instrument. Company collects data about bought gas and feeds e-gas corresponding to the amount of gas purchased by the customer back into the natural gas network. Company says that in this way completely CO2-neutral mobility is achieved.
We need as many alternatives to currently dominant fuels as possible. We do not know what future will bring, but environmentally friendly transportation is a major goal of the humanity. Therefore, A4 Avant g-tron is an interesting solution to transportation problems of the future.