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Steel is an alloy made up primarily of iron, with carbon and other metallic elements used to harden it and improve its performance. The properties of steel—such as its strength—and its relatively low cost make it suitable for many applications, such as the construction of buildings, bridges, and roads. Steel is also used to make a seemingly boundless variety of things, including cars, appliances, kitchenware, and medical equipment. Because steel is used so ubiquitously in society, steel manufacturing is a major industry worldwide. Over a billion metric tons of steel are produced each year.

About 98 percent of the iron ore mined from Earth is used to make steel. Steel is produced inside high-temperature furnaces using two main processes. About 70 percent of the world’s steel is produced in blast furnaces, using newly mined iron ore as the main input. Coke, made by heating coal, is also required to convert, or reduce, the ore to iron, which can then be made into steel. The remaining 30 percent of the world’s steel is produced in electric arc furnaces (EAF) that reprocess and refine recovered scrap steel at high temperatures. This process also requires carbon inputs, often in the form of coke. In EAF steelmaking, carbon has two main roles: removing the impurities and foaming the slag. The slag-foaming process enables by-products and impurities to be removed more efficiently during steelmaking as well as helping with temperature control and protecting the furnace from heat. It is an important part of the production process.

Steel is sometimes considered a sustainable material because of its durability and ability to be reused and recycled. However, in addition to the environmental impacts of mining the raw materials for steel—and its reprocessing in EAF steelmaking—its production consumes energy and produces various emissions, including particulates and carbon dioxide (a greenhouse gas). With the steady demand for steel worldwide, the steel industry has taken steps to reduce environmental impacts, such as developing or adopting new technologies to decrease coke usage and energy consumption. For example, polymer injection technology (PIT), also known as "green steel," uses old tires to replace some of the coke otherwise used in EAF steelmaking.

Old tires that have worn treads are unsafe for vehicles and must be replaced. Over a billion tires are manufactured each year, while old, discarded tires are stockpiled in landfills. However, tires contain carbon and can be transformed to partially replace the coke used in EAF steelmaking. Professor Veena Sahajwalla, director of the Centre for Sustainable Materials Research and Technology at the University of New South Wales in Australia, spent years pioneering PIT. The result is a new “green steel” technology that injects a precisely calibrated blend of coke and granulated tires into EAF furnaces. The use of waste tires not only reduces the demand for coke, but also improves slag foaming, which improves thermal efficiency, thereby reducing energy consumption as well as the greenhouse gas emissions associated with steel production. Working in partnership with OneSteel, Professor Sahajwalla’s green steel technology has been commercialized internationally. Since its adoption in 2008, millions of tires have been diverted from landfills around the world and have instead improved EAF steelmaking.

Here are suggested ways to engage students with this video and with activities related to this topic.

Before watching

Ask students:

• What happens to stuff when you throw it away?
• What are the benefits of the three Rs: reduce, reuse, recycle?
• What is steel? How is it made?
• Why is steel important to our society? Do some research and list five places where steel is used.

While watching

Have students look for the answers to these questions. They may watch the video more than once.

• Describe the process by which Dr. Veena Sahajwalla turns trash into steel.
• How is this process a “greener” alternative to the way steel is currently produced?

After watching

Ask students:

• Do you think that this "green steel" technology will become common practice? Why or why not?
• How do you think Dr. Sahajwalla's research will impact the environment?
• Can you think of other examples of "green" technology? Do some research to learn more about green/environmental/clean technology.