Carbon dioxide (CO₂) represents more than 70% of the greenhouse gases (GHG), which are responsible for the greenhouse effect, a natural phenomenon that directly affects and allows life on the Earth. However, over the last half-century, the CO₂ atmospheric concentration has rapidly increased to about 400 ppm due to human-related emissions, causing the well-known climate change. Of these emissions, 21% are originated from industry, in which the cement production has the largest impact.

In this scenario, many solutions using either CO₂ capture storage (CCS) or CO₂ capture and utilization (CCU) in cement industries have been investigated, including the synthesis of chemicals, polymers, fuels, and nanomaterials.

In this work, one functional unit with 2 Mtons of cement/year was adopted to compare the conversion of the captured CO₂ to carbon nanotubes (CNT) and methanol. Along with emission factors and economic evaluations, the proposed analyses were employed using material and energy balances.

The results showed that, currently, methanol seems more attractive since it can increase profits per functional unit up to 322 M€/year and allows a reduction of 8% of the total CO₂ emissions inside the cement industry, while for CNTs the values are respectively 90 M€/year and 0.01%.

Nevertheless, CO₂ conversion to CNT has the potential to increase its attractiveness in the cement sector according to the CNT market expansion in the future (carbon nanotubes would replace the large markets of iron and aluminum).