blast furnace

Less coal for making steel

September 5, 2024 By EarthWise Leave a Comment

Steel is primarily produced using one of two methods: blast furnaces or electric arc furnaces. The first blast furnaces were built in the 14th century. Making steel in a blast furnace starts by melting the raw materials of iron ore, limestone, and coal at very high temperatures. The resultant reactions ultimately lead to two products: iron saturated with carbon and carbon dioxide. A second furnace reacts the liquid iron with oxygen to remove the carbon and results in steel along with even more carbon dioxide.

Making steel using an electric arc furnace is considerably less emissions-intensive and more sustainable. So-called circular steel making powered by electric arc furnaces uses electricity to melt scrap and other input materials and turn them into high-quality steel. Of course, to really minimize the emissions associated with steelmaking, the arc furnaces need to get their power from renewable energy sources.

The global steel industry is turning away from polluting coal-fired blast furnaces and towards electric arc furnaces, which now account for roughly half of all planned new steelmaking capacity. This represents real progress towards a green steel transition.

By the end of this decade, electric arc furnaces will account for more than a third of steelmaking. However, there are still plenty of new coal-based steel furnaces being built. So even as electric arc furnaces account for a greater share of steelmaking, these new coal furnaces will still drive emissions upward. Environmental advocates argue that what the steel industry needs is to make clean development a true priority and back away from coal-based developments.

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Steelmakers Increasingly Forgoing Coal, Building Electric

Photo, posted July 16, 2018, courtesy of Daniel Steelman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cleaner And Greener Steel | Earth Wise

August 14, 2023 By EarthWise Leave a Comment

Producing construction materials like concrete and steel is a major contributor to greenhouse gas emissions. Between 7 and 8% of emissions are due to steelmaking alone, which has been done pretty much the same way for more than a century.

Iron ore is smelted with high-carbon fuel and is turned into so-called pig iron in a blast furnace, which creates the key raw material for the steel industry. The process uses huge amounts of energy (still often generated by burning fossil fuels) and releases carbon dioxide as a byproduct.

The Department of Energy is sponsoring 40 projects at universities, national laboratories and companies in 21 states aimed at reducing industrial carbon pollution. Ten of those projects are focused on decarbonizing iron and steel. These initiatives are part of the overall effort to move the nation towards a net-zero emissions economy by 2050.

A team headed by Case Western Reserve University that includes Lawrence Livermore National Laboratory, the University of Arizona, and steel company Cleveland-Cliffs Inc. has developed a promising new zero-carbon, electrochemical process for producing steel.

The process is a novel molten salt electrolysis method that is low-cost, capable of achieving high rates, and uses environmentally benign chemicals. The process does not use carbon at all. Using molten salts, electrochemistry can be performed at moderately high temperatures rather than the temperatures of nearly 3000 degrees Fahrenheit used for conventional steelmaking. The goal is to enable steel production that is both economically viable at an industrial scale and that is environmentally sustainable.

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Case Western Reserve leading research to develop zero-carbon, electrochemical process to produce iron metal as part of U.S. Department of Energy effort

Photo, posted January 11, 2017, courtesy of Kevin Casey Fleming via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Decarbonizing The Most Polluting Heavy Industries | Earth Wise

November 23, 2021 By EarthWise Leave a Comment

The production of steel, cement, and ammonia accounts for about 20% of the carbon dioxide humans pour into the atmosphere. Modern cities are largely constructed from concrete and steel and most of our food is grown using fertilizer made from ammonia.

The most widely discussed solutions to decarbonizing these industries are green hydrogen and carbon capture and storage or CCS.

Steel manufacture is responsible for 11% of society’s emissions. Most production starts by burning coal in a blast furnace. Using CCS could reduce emissions from burning the coal. But the blast furnace could be eliminated entirely by the use of electrolysis to produce the pure iron needed to make steel. This would be extremely energy-intensive but using a low-carbon source like green hydrogen could greatly reduce the emissions from making steel.

Ammonia is made by producing hydrogen from natural gas and then combining it with atmospheric nitrogen. Both the hydrogen production and ammonia synthesis are energy intensive. Using green hydrogen would eliminate emissions from the hydrogen production itself and new research on catalysts aims at lower-temperature, less-energy intensive ammonia synthesis.

Decarbonizing cement manufacturing is perhaps the toughest challenge. Cement is made in a high-temperature kiln, typically heated by burning fossil fuels. The process converts calcium carbonate and clay into a hard solid called clinker. The main byproduct of that is even more carbon dioxide. Burning green hydrogen and capturing carbon emission are about the best hope for reducing cement manufacturing emissions.

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Can the World’s Most Polluting Heavy Industries Decarbonize?

Photo, posted June 30, 2009, courtesy of Portland Bolt via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.