The Aluminium Fuel Tank, a Lightweight Solution 2001-01-3172

A major objective of the European car manufacturers is to reduce the fuel consumption and CO2-emissions of passenger cars by 25% by the year 2008. As the fuel consumption is strongly related to the weight of the car, realisation of this objective will be achieved by long term weight reduction programmes.

The European fuel tank market consists of around 14 Million units in cars, of which approximately 70% contain HDPE (High Density Poly Ethylene) fuel tanks, 17% leaded (Terne) steel, 3% aluminised steel and the remainder miscellaneous such as electro-coated Zn-Ni, galvannealed, hot-dipped tin or multi - layers with new substrates.

The future legal regulations for fuel tanks will be dictated by the latest CARB (Californian Air Resources Board) specification LEV II (Low Emission Vehicle II). The main demand is the reduction of hydrocarbon (HC) emission for the total car from 2 down to 0.5 g / day in 2004. This demand appears doubtful for plastics, but is feasible for metal tanks.

Next to the barrier technology and low permeability of the material, other demands are; good recyclability (80% of the vehicle must be recycled by the year 2005), low weight (reduction of CO2), noise, and no toxic metals (terne) by the year 2005.

All these factors favour aluminium as the raw material for manufacturing the fuel tanks of passenger cars. The fuel tank constructions are often very complex in shape because of the residual space left in the designed car, and therefore tend to be made of plastics due to their good formability. New and break through forming processes now make it possible to use aluminium in applications even with very complex shapes.

Although hybrid vehicles and fuel cell technology are making rapid progress, fossil fuels will continue to be used as the primary source of power certainly for the beginning of this new century.

This paper highlights some of the latest technologies and recent product requirements in fuel tanks with respect to the environmental demands, manufacturability and costs.