Reducing Emissions From Cement & Steel Production

There’s more to lowering atmospheric carbon dioxide levels than driving electric cars. Decarbonizing the cement and steel industries will be equally as important.

We tend to focus a lot here at CleanTechnica on the electric revolution in the transportation sector, but there are lots of other industries that are major contributors to the world’s carbon emissions. Making steel and cement are two of the biggest. “Each year, more than 4 billion tons of cement are produced, accounting for around 8 per cent of global CO2 emissions,” according to Chatham House in the UK. Making steel accounts for a similar amount of carbon emissions — between 7 and 9 per cent according to the World Steel Association.

Combined, these two industries — both central to the construction industry — are responsible for about 15% of all the world’s carbon emissions every year. That means the opportunities to lower the amount of carbon dioxide they create are significant. Fortunately, leaders in both industries are finding new ways to do precisely that.

Reduction In Carbon Emissions From Cement

90% of the carbon emissions from making cement come from two sources, both essential to the process. To make cement, limestone is heated to very high temperatures in kilns to transform it into clinker, which is then ground up into a fine powder. The calcification process itself releases a large volume of carbon dioxide. But the fuel used to heat those kilns also produces large amounts of CO2. The road to low carbon cement involves using zero emissions fuels as well as finding acceptable substitutes for clinker derived from limestone.

The Global Cement and Concrete Association, which represents 40 of the world’s largest cement manufacturers, launched a new initiative on September 1 to make the industry carbon neutral by 2050. Its objectives are to reduce or eliminating energy related emissions by using low or zero carbon fuels, reducing process emissions through new technologies and deployment of carbon capture, promoting more efficient ways of using concrete, reusing and recycling of concrete and buildings, and harnessing concrete’s ability to absorb and store carbon from the atmosphere.

Albert Manifold, president of the association, says “The 2050 Climate Ambition represents our industry’s commitment to further reducing emissions and ensuring that the vital product we provide can be delivered on a carbon neutral basis by 2050. There is a significant challenge involved in doing so and achieving alignment across our industry on a sustainable way forward is an important first step. We cannot however succeed alone and in launching our ambition statement we are also highlighting the need for our industry to work collaboratively with other stakeholders in support of our ambition for a more sustainable future.”

McKinsey & Company reports “our analyses show that CO2 emissions could be reduced by 75 percent by 2050. However, only a small portion (around 20 percent) will come from operational advances, while the remainder will need to come from technological innovation and new growth horizons.” Those innovations include substituting waste products from other industries such as fly ash or reclaimed concrete for some of the clinker. McKinsey also says carbon capture may play a significant role. Since the flue gases from the calcification process are composed mostly of carbon dioxide, they are ideal for carbon capture technology. Some early experiments suggest adding some of that carbon dioxide back into uncured concrete can result in a stronger, more durable finished products.

Substituting renewable energy for the fuels used in the calcification process is an important first step but it does not address the emissions created by the chemical changes that occur during the process itself. For that, new forms of cement will be needed and that is a major challenge.

Economics are another significant challenge. Alternatives to traditional cement are more expensive. As McKinsey & Company report, “Cement manufacturers are faced with a dilemma: there is pressure from the public and financial investors to abate quickly, even though there is no economic rationale to do so.” In other words, the world desperately needs low carbon cement but operates using an economic model that rewards doing nothing. “Lord, what fools these mortals be,” opined William Shakespeare.

 Making Low Carbon Steel

The key to making low carbon steel is simple. Converting iron into steel using traditional methods involves large amounts of coke — coal that has been baked at high temperatures until it loses most of its impurities. What’s left is almost pure carbon. When used to make steel, it results in lots of carbon emissions. But if hydrogen is substituted for coke, the only waste product is water.

In Sweden, a pilot factory started operations recently to make zero emissions steel using hydrogen as a reducing agent in place of coke. The HYBRIT project is a collaboration between Swedish companies SSAB, LKAB and Vattenfall. At the opening ceremony, Sweden’s prime minister Stefan Löfven said, “Right now we have a historic opportunity to do things that provide jobs here and now but also hasten the climate transition that everyone realizes is necessary. Today, you are laying the foundations that will enable the Swedish steel industry to be entirely fossil fuel and carbon dioxide free in 20 years. Together we can rebuild Sweden as the world’s first fossil free welfare nation.”

During the next few years, the HYBRIT facility will perform tests in how to use hydrogen in the direct reduction of iron ore. The hydrogen will be produced at the pilot plant by electrolyzing water using electricity from renewable sources. With HYBRIT as the model, SSAB, LKAB and Vattenfall seek to create a completely fossil fuel free value chain from mine to finished steel. The key will be using hydrogen instead of coke to reduce iron ore.

Making steel from iron takes a lot of energy no matter what process is used. Originally, steel mills used coal but recently some have switched over to using natural gas. While hydrogen may be used in the reduction process, it can also be used as a fuel to power the steel mill itself, especially the rolling machines that turn molten steel into sheets. That is what Ovako, another Swedish steel company, is doing on a trial basis.

Green Technology Needs Green Policies

Reducing emissions from the cement and steel industries will be vital to lowering total carbon emissions worldwide. Along with new technologies, decreasing the use of fossil fuels in the process will help lower emissions as well. But the biggest driver of change should be appropriate economic policies. Decarbonization will not come cheap. The absence of a global standard that prices the cost of using fossil fuels into macro-economic models means those who do the least get rewarded the most. It’s time for nations to adopt a universal fee to address that glaring imbalance.