The entire world is constructing and manufacturing things that have never been seen before—roads, hospitals, cars, furniture; new things appear every day. This is good news for those who benefit from these new things and new infrastructures, but it also makes the manufacturing and construction industries extremely thirsty for raw materials.

Since 1971, human demand for steel has tripled, the demand for aluminum has increased sixfold, and the demand for cement has nearly septupled.

All of these point to an increasingly severe climate issue, as the manufacturing, use, and disposal of certain materials produce a large amount of emissions. In total, the greenhouse gas emissions produced by global material production account for about a quarter of today's total global emissions.

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I have always found this fact to be thought-provoking. After all, cement sidewalks do not visibly emit carbon dioxide into the air like power plants do.

Nevertheless, for climate action, these gray materials may pose a greater challenge than power stations. So now let's delve into why the climate issues caused by material production are less eye-catching.Let's start with steel. Steel can be said to be the largest and most troublesome "climate problem" in the material world. According to data from the International Energy Agency, steel production generates about 2.6 billion tons of carbon dioxide annually, accounting for about 7% of all energy-related emissions.

If you understand the steelmaking process, you will know why it becomes a nightmare for climate issues. Most traditional steel manufacturers rely on a piece of equipment called a blast furnace, which can reach temperatures of over 1000°C. At such high temperatures, a chemical reaction occurs between iron ore and a coal-derived material called coke.

Achieving such high temperatures requires a lot of energy consumption, and fossil fuels are the core of steel production today. From the scaffolding of large buildings to the frames of vehicles, the steel in all these items may be related to these greenhouse gases.

Some companies are looking for alternatives to help produce cleaner steel. The startup H2 Green Steel hopes to replace fossil fuels with hydrogen. The company is building the world's first commercial-scale green steel plant in Sweden and says it will produce 2.5 million tons of steel by 2026.

Other companies are trying to smelt steel with electricity. Boston Metal's approach will use an electrochemical reactor instead of a blast furnace.The company plans to have an industrial-scale facility ready by 2025 or 2026, but as my colleague David Rotman explained, entering a massive and conservative industry like steel manufacturing will be a challenge.

Although high temperatures and huge energy demands are one of the main sources of emissions related to materials, they are not the only ones. Consider cement, a key ingredient in concrete. I bet you can easily spot this unassuming gray substance around you right now.

The carbon dioxide produced by cement production accounts for more than 7% of the global total emissions. Like steel, cement also requires a large amount of energy to manufacture, and the operating temperature of cement kilns is usually higher than the temperature during a volcanic eruption.

However, energy use actually only accounts for half of the climate issues caused by cement. The other half comes from the so-called "direct emissions," which are emissions from the chemical processes required to manufacture cement.

Transforming crushed rocks into usable building materials involves complex chemical reactions, some of which release carbon dioxide. Therefore, cement production causes "double" climate troubles.Therefore, making cement production cleaner will involve two related but distinctly different challenges: powering the process without burning fossil fuels, while also striving to avoid emissions produced by chemical reactions.

Startup company Sublime Systems is working to address both of these issues. Founded by two battery scientists from MIT, the company is developing a process that relies on water and electricity to make cement, replicating the same work done in cement kilns.

Although the team's process started on a small scale, producing cement small enough to fit in the palm of your hand, the company has since scaled up.

Sublime currently operates a pilot line capable of producing about 100 tons of cement per year and plans to open a larger demonstration facility in early 2026. After that, it plans to build a larger factory around 2028.

Making the materials we rely on cleaner is a daunting task, and cement and steel are just two small parts of the entire puzzle: combating climate change also requires reshaping our processes for manufacturing and using other materials such as aluminum and plastics.