Aluminum

The world consumes about 90 million tons of aluminum each year, a number that's set to increase significantly  2050. Aluminum is prized for its low weight and for its high strength-to-weight ratio. What’s aluminum’s carbon footprint? Aluminum was responsible for 1.1 billion tons of carbon dioxide equivalent (CO2e) in 2018, representing about 4% of global emissions. This is less than steel and cement (~8% each). However, the world uses less aluminum than steel or cement, meaning that, per ton, aluminum is actually a top playing carbon-intense of the emitting materials. Around 16 tons of CO2e are produced per ton of aluminum.
 

What causes aluminum emissions?

Aluminum is produced in the following stages:
 

Mining

Bauxite is extracted from the earth and is made up of 15-25% aluminum. Mining bauxite isn’t particularly carbon-intensive. 
 

Refining

Since bauxite has a relatively low value, it’s typically refined to aluminum oxide, or alumina, in the country of mining. Refineries are usually located on the coast to facilitate easy shipping of alumina to smelters.  Refining is moderately carbon intense, contributing 2.6 tonnes of CO2 per ton of aluminum. Those emissions are largely from the burning of fuels to produce heat.
 

Smelting

The most energy-intense and carbon-intense step of aluminum production is the smelting of alumina to aluminum, which occurs through electrolysis: a hugely energy-intensive process. Because they use so much electricity, the majority of smelters are situated where electricity can be produced very cheaply. 
 

Closing the loop:  Aluminium’s Circularity
Aluminium’ is one of the most recyclable of all materials. Aluminium can be reused over and over again, meaning both aluminium and its alloys can be melted down and reused without any detriment to its mechanical properties. Therefore end-of-life products should be returned into the aluminium recycling loop. Focus for innovation in recycling aluminum should be on:

-Eco-friendly designs

-Improved sorting technologies

-Appropriate policies, and investment

-Transformation of consumer purchasing habits and lifestyle
 

However, not all recycled aluminum is equal.
 

• When recycled aluminum is made from used windows or car parts, the material starts another life. Previously used aluminium known as “post-consumer” scrap, has a carbon footprint that is close to zero.
   

• Recycled aluminum made from production scrap or “pre-consumer” scrap has not yet completed its life and must therefore retain the carbon footprint of its original production process. If this isn’t done, the material’s production emissions are not accounted for.