Steel and cement are very different in their attributes, functions, and specific uses. However, they are essential requirements for the functioning of modern societies. They are needed in larger quantities, and their demand has been increasing for many years. Globally, 4.1 billion tons of cement and 1.8 billion tons of steel were used in 2023 (World Cement Association). Both materials are so essential that it is unlikely they will be replaced by any other material in the coming decade.
Most people recognize the importance of steel and cement to a country’s development. Producing these materials relies heavily on burning fossil fuels, making them central to the challenge of reducing emissions and decarbonization. Collectively, 10 to 15% of global primary energy supply is consumed by sectors of cement and steel, while they also contribute close to 20% of global CO2 emissions (IEA, 2024).
Multiple experimental techniques and different methods have been applied. Small-scale startups have been working to produce these materials without the use of fossil energy, but none of the alternative processes are yet commercialized. Manufacturing of both these materials using conventional technology is cheap; in some cases, less than $150/ton. However, on a ton basis, they generate more emissions than many other products being manufactured at scale. For each ton of steel, 1.8 tons of CO2 are released, while 1 ton of cement releases 1 ton of equivalent CO2 (Barbhuiya et al., 2024; Watari & McLellan, 2024).
It is important to understand the interrelationship between steel and cement with fossil fuels and to appreciate the technical advancements that are making them abundantly available and affordable for modern-day use.
Steel: The Structural Pillar of Modern Civilization
There are more than 3,000 varieties of steel alloys consisting of 95 to 97% of iron, 1.5 to 4% of carbon, 0.5 to 3% of silicon, and minor quantities of other elements. The world consumes a lot of steel and relies on it. Why? Its high carbon content makes it brittle, easy to shape, and it can stretch; it is seven times stronger than aluminum and four times stronger than copper. Moreover, steel melts at 1,425°C, which is higher than both copper and aluminum. The major component in steelmaking is iron, which is one of the most common elements on Earth because it forms the planet's core. World resources of iron ore are in excess of 800 billion tons, whereas annual production is 2.5 billion tons, which is more than 300 years of resources. The second element in steelmaking is coal, which can also be extracted from immense coal reserves in the world that can last for many decades.
Getting both iron ore and carbon from coal is easy and inexpensive; technology has been developed, and reserves are plentiful. In the steelmaking process, iron is required in pure form, whereas iron ore is with oxygen. To separate the two elements, iron ore is heated at a temperature of 1,700 to 3,000°C, in the presence of oxygen and coke to provide carbon. At this temperature, iron releases oxygen and bonds with carbon to form steel. The remaining carbon reacts with oxygen released from iron to form CO2 gas.
The total energy required to make the finished steel product is in the range of 17 to 20 GJ/ton of steel. Some less-efficient steelmaking practices may require a higher amount of energy in the range of 23 to 25GJ/ton. In 2023, 38 exajoules, a little more than 6% of global primary energy, were consumed in making steel (Watari & McLellan, 2024).
Steel is also recycled in a process that involves massive electric arc furnaces (EAFs), made of heat-resistant materials with huge carbon electrodes. In the steel-recycling process, steel scrap is loaded in EAFs, and electrodes are lowered onto it, which produces an electric arc of high temperature in the range of 1,700 to 1,800°C, melting down the steel and making it possible to produce other steel products. Except for large ships or other giant steel bodies, this is the most-challenging recycling operation; almost all steel structures can be recycled easily and have high end-of-life steel recovery rates (Hundt & Pothen, 2025). All the recycled steel can be used in steel beams and plates. However, the electricity demand and skilled work for this recycling process is massive.
Overall, steel is an essential requirement for infrastructure development and for other modern uses, but it comes with the cost of using an enormous amount of energy, followed by greenhouse-gas (GHG) emissions. Nevertheless, steel is not the only high-output and energy-intensive material; another material is cement, which has a greater impact than steel in the modern world.
Concrete: Building the World With Cement
Concrete mainly consists of aggregates (60 to 80%) and water (15 to 20%), while cement, an aggregate, is the essential part of concrete. It is mainly produced by ground limestone (extracted from calcium), clay, shale, and waste materials. The concrete's final mass comprises 10 to 15% of cement. It can withstand years of hard and severe use, particularly when it is reinforced with steel.
At the industrial scale, concrete production needs the mixing of gravel, sand, water, and cement. Acquiring the first three items is relatively easy; it is the cement where things start to get messy. Cement is produced from calcium, and calcium is treated in a furnace with some other materials at high temperature, separating calcium and releasing CO2 (Gates, 2021). Manufacturing cement requires both thermal and electrical energy, and in best practices, it requires energy of 3.3–4.2 GJ/ton (IEA).
One example that can help the world understand how cement is a vital material and one of the important pillars of modern society is by analyzing the modernization drive of China in the late 20th century. The country’s annual cement production rose to 80 million tons, which rose to 2.4 billion tons in 2019. Perhaps the most stunning statistic is that in just 2 years, 2018–2019, China's total output of cement was close to 4.4 billion tons, nearly the same as the US's during the entire 20th century (4.56 billion tons).
Steel and Cement as Critical Inputs for Decarbonization Pathways
Considering the global requirements for steel and cement, their dependence on fossil-fuel combustion for production and the nonavailability of alternate operations that can replace these processes at the industrial scale, it seems doubtful that cement and steel manufacturing will achieve fossil-fuel independence by 2050. Materials dependence can be reduced but not eliminated.
As the world continues its transition to renewable-energy, it will require an unprecedented amount of steel and cement-based materials, demand that can only be met through the fossil-fuel operations the industry relies on today.
An example is a wind turbine and its material requirements. The foundations for wind turbines require an enormous amount of concrete, while their rotors and towers are made of approximately 200 tons of steel per installed MW of generating capacity. Other parts, such as blades, gearboxes, and steel cranes, are essential requirements. If we multiply these requirements by the millions of wind turbines needed to generate the world’s green electricity, we gain a more realistic perspective on current discussions about dematerialization and green economies.
Another example of material dependency is electric vehicles (EVs). A typical EV weighs around 450 kg, of which 181 kg is steel, aluminum, plastics, and other materials. Supplying these materials requires processing of 225 tons of raw materials for a single EV. As noted above, multiplying these material requirements by the annual global production illustrates the scale of future material dependency (Lucchini et al., 2024).
Decarbonizing Steel and Cement: Global Efforts
As discussed, steel and cement are the hardest sectors to decarbonize due to their inherent process emissions and extreme energy requirements. Still, multiple technological pathways are advancing globally toward fossil-free manufacturing of these materials. As of now, the most promising low-carbon alternative is hydrogen direct reduction (H-DRI), which reduces iron ore to metallic iron. In this process, H2 strips O2 from the ore, producing only water vapor as a byproduct and lowering tons of CO2 emissions.
Another pathway is the electrification of EAFs, powered by renewable energy, supported by scrap-steel recycling, and enhanced by innovative technologies such as molten oxide electrolysis, which have the potential to eliminate CO2 emissions from iron reduction. SSAB HYBRIT, a joint venture in Sweden, delivered the world's first fossil-free steel using the H-DRI technology and hopes to achieve commercial conversion by 2035. Another company, ArcelorMittal, has demonstrated a diversified strategy combining H2 injection into traditional furnaces and H-DRI, with more demonstrations and planning expected throughout 2025.
Although it is a slow transition, both technologies offer a realistic pathway toward decarbonization, particularly when dedicated renewable energy and carbon capture, utilization, and storage infrastructure are available to power the industrial process.
Conclusion
Steel and cement are essential components of modern society, and these materials will be needed for new tools, machines, infrastructure, making solar panels, installing wind turbines, running EVs, and making storage batteries.
These materials continue to rely on fossil-fuel operations and renewable energy conversion. The convergence of breakthrough innovations such as H-DRI and EAFs, coupled with electrification and advanced thermal processes, offers a way forward, but progress remains slow. Modern societies are likely to remain substantially reliant on fossil fuels for the production of cement and steel. Advancements in emerging technologies like artificial intelligence, quantum computing, and digital applications may contribute to efficiency gains and support the expansion of other strategies, including carbon capture and the development of new materials that reduce dependencey. However, it will take time to fully eliminate reliance on fossil-fuel operations.
For Further Reading
Roadmap to a Net-Zero Carbon Cement Sector: Strategies, Innovations, and Policy Imperatives by S. Barbhuiya, University of East London, B. Bhusan Das, National Institute of Technology Karnataka, and D. Adak, NIT Meghalaya.
Cement and Concrete as an Engineering Material: A Historic Appraisal and Case Study Analysis by C. Gagg, The Open University.
How to Avoid a Climate Disaster: The Solutions We Have and the Breakthroughs We Need by B. Gates.
European Post-Consumer Steel Scrap in 2050: A Review of Estimates and Modeling Assumptions by C. Hunt and F. Pothen, University of Applied Sciences.
Demand and Supply Measures for the Steel and Cement Transition, IEA
Current Trend in Offshore Wind Energy Sector and Material Requirements for Fatigue Resistance Improvement in Large Wind Turbine Support Structures: A Review by V. Igwemezie, A. Mehmanparast, and A. Kolios.
A Survey on the Sustainability of Traditional and Emerging Materials for Next-Generation EV Motors by F. Lucchini, R. Torchio, and N. Bianchi, University of Padova.
How the World Really Works by V. Smil
Decarbonizing the Global Steel Industry in a Resource-Constrained Future—A Systems Perspective by T. Watari and B. McLellan
