Metal production and greenhouse gases

The construction and industrial minerals and metals consumed annually in the US amount to about 2.3 billion metric tons. Metals constitute a small fraction (<5%) of this total mass but play a much larger role in economic development. In 1991, their production (SIG 33) required 2.4 EJ (10(18) Joules) of energy, representing 15.3% of US industrial energy consumption, or about 2.7% of total US energy consumption. Here we examine three metals, steel, aluminum, copper, that together represent over 98% of all metal consumption by weight. The continuing evolution of the technologies used for metals production and the character of feed materials has significant impacts on this sector's energy consumption. To link energy usage with carbon emissions, we examine the mix of fuels (i.e., coal, oil, gas, electricity) used in metal production. Our analysis expands on the work of Forrest and Szekely(1) in assessing the contribution of primary metals production to greenhouse gas emissions. Technological advances in the second part of this century have reduced considerably the energy consumption per unit of metal and there is potential for further reduction of carbon dioxide emissions from metal production. However, increasing the fraction of recycled metals offers the greatest opportunity for limiting CO2 emissions and for conserving Earth resources.