Chapter 1: The Climate Impact of Concrete and Steel

Concrete and steel, while not fossil fuels, represent significant contributors to global carbon emissions. These materials are fundamental to modern construction, enabling the creation of impressive structures like bridges and skyscrapers. However, their production processes are major sources of greenhouse gas emissions.

The manufacturing of cement, a key component of concrete, results in approximately 0.6 tons of carbon dioxide for every ton produced. This translates to nearly 0.2 tons of CO2 emissions per ton of finished concrete. The process begins with mining and crushing limestone, which is then heated in a kiln—typically using fossil fuels—transforming it into quicklime. This heating process releases carbon dioxide, which combines with oxygen to form CO2. The quicklime is then combined with clay and further heated in a cement kiln to produce clinker, which is ground into cement.

Cement production alone accounts for about 8% of global CO2 emissions, exceeding the emissions from aviation, marine shipping, or hydrogen production. Notably, around 40% of these emissions stem from the fossil fuels used in the process, making this a solvable challenge through electric heating methods, with some electrified cement kilns already in operation.

However, the more significant issue lies with the 60% of emissions resulting from the carbon dioxide released during the limestone calcination. Although there are various alternatives available, they tend to be more expensive, making carbon capture and sequestration a viable option in this context. Implementing carbon pricing will further incentivize the transition to lower-carbon solutions.

The widespread use of concrete is primarily due to its low cost, which often outweighs concerns about potential structural failures. One effective strategy to minimize emissions is to adhere strictly to engineering requirements, avoiding the overuse of concrete, which can sometimes exceed necessary amounts by two or three times. As carbon costs rise, the industry will likely shift towards more efficient practices and lower-carbon materials.

A significant barrier to adopting alternative materials is the rigid nature of building codes, which can vary greatly by location and often dictate specific concrete compositions, complicating the introduction of greener options.

Steel also contributes approximately 8% of global greenhouse gas emissions. Much of this steel is embedded within concrete, serving as rebar that enhances structural integrity. The traditional steel manufacturing process involves converting iron ore into iron using coal, which is then transformed into steel, resulting in substantial emissions.

Nevertheless, advancements in steel production are paving the way for a cleaner future. Currently, about 100 million tons of steel are produced annually using direct iron reduction methods, which utilize synthetic gases derived from natural gas or coal. These gases can potentially be replaced with bio-sourced alternatives, and the heating requirements can be met through electric means. Companies like Midrex are leading the charge in these innovations.

In the U.S., a significant portion of steel demand—around 70%—is met through scrap steel processed in electric arc furnaces. While fossil fuels are often employed for heating in conjunction with electric arcs, a fully electric process powered by low-carbon electricity is achievable.

Emerging methods utilizing green hydrogen or direct electricity for iron production from ore are also being tested successfully in various locations, including Europe and Australia.

Over the coming decades, steel demand is expected to stabilize, particularly as major industrialization efforts in China slow and population growth levels off. This shift will likely lead to increased recycling of existing steel and the adoption of low-carbon manufacturing techniques.

Both concrete and steel can be decarbonized; the key lies in incorporating the environmental costs of emissions into their production pricing. Initiatives like Europe's 2026 carbon border adjustment mechanism will facilitate this transition by effectively imposing a carbon price on imported goods.

Chapter 2: Other Industrial Sectors in Need of Decarbonization

Beyond concrete and steel, various other industries also require significant emissions reductions. For instance, the production of baking soda results in substantial carbon dioxide emissions. The traditional Solvay process has contributed to greenhouse gas emissions for over a century. However, innovative approaches in electrochemistry can now produce baking soda while utilizing excess CO2 emissions.

Ultimately, there are no significant technical challenges preventing the decarbonization of major industrial emitters—only the commitment to invest in necessary changes. This makes the revitalization of steel, cement, and other industrial processes a high-priority item on the climate action agenda.

The following strategies encapsulate the essential actions for addressing climate change:

• Electrify all systems
• Expand renewable energy generation
• Develop extensive electrical grids and markets
• Implement pumped hydro and other storage solutions
• Increase tree planting efforts
• Revise agricultural practices
• Improve concrete and steel production methods
• Enforce aggressive carbon pricing
• Phase out coal and gas generation
• Cease fossil fuel financing and subsidies
• Eliminate HFCs in refrigeration
• Maintain focus on key priorities
• Address underlying motivations

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