In a Weight Class of its Own
We Americans love our cars, but what is actually under the hood? The majority of raw materials that are extracted from the earth and processed in order to produce a car never make it into the final product. As a representative vehicle, the 2012 Ford Fusion has a curb weight of 1485 kg, mostly steel, copper, aluminum, and plastic.[1]
The metals come from mining and refining of ores, and each one a certain concentration in natural deposits, called the ‘ore grade’. Globally, iron has a high average ore grade of 45%, while the value for copper is just 0.5%.[2] The lower the ore grade, the more host rock has to be blasted, excavated, and milled in order to produce the desired metal. In addition, before mining even commences, vast quantities of dirt and rock (called ‘overburden’) must be removed just to reach an ore deposit, with estimates of nearly 2-to-1.
Plastics, on the other hand, are made from oil and gas, which are extracted along with water. This ‘produced water’ makes up approximately 87% by mass of what is extracted from oil and gas wells.1 In sum, the ‘total material requirement’ of a car, or the total mass of material needed for its production, exceeds its actual weight by 25 times.
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[1] US DOE. 2015. GREET vehicle powertrain materials. Argonne National Laboratory, US Department of Energy. Washington DC. https://greet.es.anl.gov/files/2015-powertrain-materials
[2] Mudd, G. 2005. Accounting for Increasing Mine Wastes in the Australian Mining Industry. Proc. 1st Int Conf on Engineering for Waste Treatment, Albi, France, May 2005.