Car makers are facing increasing regulations on vehicle emissions as governments take action to combat climate change. Typically the targets have only focussed on emissions during the use phase of the vehicle’s life – also known as tailpipe emissions.
At ArcelorMittal we believe that the entire life cycle of the vehicle should be taken into account when setting emission targets. If tailpipe emissions alone are considered, it is tempting for car makers to substitute steel with lighter materials. While lighter materials might lower emissions during use, they may have a higher carbon footprint during the production and end-of-use phases of their life. Unlike steel which is 100% recyclable at the end of its useful life, many materials cannot be recycled completely.
Using LCA to quantify emissions from vehicles shows that steels, and in particular advanced high strength steels (AHSS), have the potential to significantly reduce life cycle greenhouse gas (GHG) emissions. Development of AHSS and technologies such as laser welded blanks (LWBs) ensure that the right steel is in the right place. This enables manufacturers to achieve significant weight reductions.
Compared to steel, materials such as carbon fibre reinforced plastic (CFRP) have very high levels of GHG emissions during the production phase. For example, producing a body-in-white (BIW) from CFRP will result in production emissions 6 times higher than if the BIW was made from AHSS. Producing the BIW in aluminium will create the same level of emissions as it takes to make four BIWs from AHSS.