A recent article in an automobile publication reports that in its quest to save weight, Volkswagen is dropping aluminium from plans to replace it with steel. Instead, VW is using new high strength steels to make the cars lighter and to comply with strict emissions rules.
This counterintuitive move – the common belief has always been that steel is on the way out and aluminium is on the way in – has surprised many.
VW explains that the new high strength steels are six times stronger than conventional steels and helped take 100 pounds (45kg) of weight out of the new VW Golf.
While aluminium is lighter than conventional steel, it is three times as expensive as the new steels , requires seven times as much energy to produce from the ore (155MJ/kg) compared with the blast furnace – oxygen steelmaking route (22MJ/kg) and on average generates 9.8tCO2eq/tAl compared with an average of 1.959kgCO2eq/t for integrated steelmaking.
Hence, if CO2 emissions are measured in terms of the whole life of a vehicle (manufacture plus use) rather than the simplistic tailpipe emissions adopted by most legislators, using steel results in an overall reduction of emissions.
However, the continuing battle between steel and aluminium is nowhere near over, but this is great news for the steel industry.